{"collection":"philosophy-ethics","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_39751/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_39751","id":"gutenberg_39751","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/39751","summary":null,"tags":["Category: Philosophy & Ethics","Category: Science - Biology","Eugenics","Genetics"],"text":"Produced by Bryan Ness and the Online Distributed\nProofreading Team at http://www.pgdp.net (This file was\nproduced from images generously made available by The\nInternet Archive.)\n\n\n\n\n\n\n\n\n\nBEING WELL-BORN\n\n\n\n\n  BEING WELL-BORN\n\n  AN INTRODUCTION TO EUGENICS\n\n\n  _By_\n  MICHAEL F. GUYER, PH. D.\n  Professor of Zoology, The University of Wisconsin\n\n\n  Childhood and Youth Series\n\n  _Edited by_ M. V. O'SHEA\n  Professor of Education, The University of Wisconsin\n\n\n  INDIANAPOLIS\n  THE BOBBS-MERRILL COMPANY\n  PUBLISHERS\n\n\n\n\n  COPYRIGHT 1916\n  THE BOBBS-MERRILL COMPANY\n\n  PRESS OF\n  BRAUNWORTH & CO.\n  BOOKBINDERS AND PRINTERS\n  BROOKLYN, N. Y.\n\n\n\n\nTO MY WIFE\n\nHELEN M. GUYER\n\n\n\n\nEDITOR'S INTRODUCTION\n\n\nThe writer recalls that when he was a young boy, he heard the grown-up\npeople in the community earnestly and incessantly debating the question:\nDoes heredity play a greater part in shaping one's mind and body than does\nhis environment? From that day to this he has listened to men and women in\nevery walk of life discussing the relation of heredity to environment in\ndetermining human traits. Teachers and parents are constantly asking: \"Are\nsuch and such characteristics in my children due to their inheritance or\nto the way they have been trained?\" Students of juvenile delinquency and\nof mental defect and deficiency are searching everywhere for light on this\nmatter. It is not to be wondered at that practically all people are\npeculiarly interested in this problem, since it concerns intimately one's\npersonal traits, and it constantly confronts any one who is responsible\nfor the care and culture of the young.\n\nIt is suggestive to note how people differ in their views regarding the\nextent to which a child's physical and mental qualities and capacities are\nfixed definitely by his inheritance. The writer has often heard students\nin university classes discuss the subject; and their handling of the\nproblem has shown how superficially and even superstitiously most persons\nregard the mechanism and functions of heredity. It is significant also to\nobserve what extreme views many people hold regarding the possibility of\naffecting a child's traits and abilities by subjecting him to specific\ninfluences during his prenatal life. In any group of one hundred persons\nchosen at random, probably seventy-five will believe in specific prenatal\ninfluence. Many of them will believe in birthmarks due to peculiar\nexperiences of the mother. A popular book recently published asserts among\nother things that if a mother will look upon beautiful pictures and listen\nto good music during the prenatal period of her child, the latter will\npossess esthetic traits and interests in high degree. On the other hand,\npeople generally do not seem to think that degenerate parents beget only\ndegenerate children. Alcoholics, feeble-minded persons and the like are\npermitted to bring children into the world.\n\nVery few people have any precise knowledge of the mechanism of heredity.\nThe whole thing is inscrutable to them, and is shrouded in mystery.\nSuperstition flourishes among even intelligent persons in respect to\nheredity, and errors due to education, and tragedies resulting from\nvicious social organization are all alike ascribed to its uncontrollable\nforces. Most people are none the wiser because they do not know to what\nextent the physical and mental defects and deviations of individuals are\ndue to inheritance or to the malign influences of the individual's\nenvironment and training.\n\nProfessor Guyer, who has studied the whole problem in a thoroughgoing,\nscientific way, has prepared this book with a view to illuminating some of\nthe mysteries that surround the subject of heredity, and to dispelling\nthe illusions that persist regarding it. He shows the method which nature\nfollows in the development of the individual. He presents the laws which\nhave become established respecting the extent to which and the manner in\nwhich immediate and remote ancestors contribute to the child's physical\nand mental organism. He answers many questions which those who are engaged\nin social work or in education in the home or the school are asking\nto-day. He discusses subjects upon which every serious-minded person\nwishes to be informed. He has thus made a book which is both of\ntheoretical and of practical interest.\n\nHe has written in a style which should make his book attractive to the\nparent and the teacher as well as to the student of the complicated\nmechanism of inheritance. Only a few special terms are used, and these\nshould not give any reader trouble, because the treatment throughout is so\nconcrete that the meaning of the terms will be easily grasped. Further,\nthe book is illustrated, with many attractive and instructive\nillustrations which will show at a glance the working of the principles of\ninheritance which are developed in the text.\n\nThis book may be heartily commended to all who are interested in questions\nof human nature, education and social reform. It should enable the parent,\nthe teacher and the legislator to understand more clearly than most of\nthem now do in how far children's traits and possibilities are or can be\nfixed by inheritance as contrasted with environmental conditions and\nnurture in home, school, church and institutional life.\n\nM. V. O'SHEA.\n\nMadison, Wisconsin.\n\n\n\n\nPREFACE\n\n\nOne of the most significant processes at work in society to-day is the\nawakening of the civilized world to the rights of the child; and it is\ncoming to be realized that its right of rights is that of being well-born.\nAny series of publications, therefore, dealing primarily with the problems\nof child nature may very fittingly be initiated by a discussion of the\nfactor of well-nigh supreme importance in determining this nature,\nheredity.\n\nNo principles have more direct bearing on the welfare of man than those of\nheredity, and yet on scarcely any subject does as wide-spread ignorance\nprevail. This is due in part to the complexity of the subject, but more to\nthe fact that in the past no clear-cut methods of attacking the manifold\nproblems involved had been devised. Happily this difficulty has at least\nin part been overcome.\n\nIt is no exaggeration to say that during the last fifteen years we have\nmade more progress in measuring the extent of inheritance and in\ndetermining its elemental factors than in all previous time. Instead of\ndealing wholly now with vague general impressions and speculations,\ncertain definite principles of genetic transmission have been disclosed.\nAnd since it is becoming more and more apparent that these hold for man as\nwell as for plants and animals in general, we can no longer ignore the\nsocial responsibilities which the new facts thrust upon us.\n\nSince what a child becomes is determined so largely by its inborn\ncapacities it is of the greatest importance that teachers and parents\nrealize something of the nature of such aptitudes before they begin to\nawaken them. For education consists in large measure in applying the\nstimuli necessary to set going these potentialities and of affording\nopportunity for their expression. Of the good propensities, some will\nrequire merely the start, others will need to be fostered and coaxed into\npermanence through the stereotyping effects of proper habits; of the\ndangerous or bad, some must be kept dormant by preventing improper\nstimulation, others repressed by the cultivation of inhibitive tendencies,\nand yet others smothered or excluded by filling their place with desirable\ntraits before they themselves come into expression.\n\nWe must see clearly, furthermore, that even the best of pedagogy and\nparental training has obvious limits. Once grasp the truth that a child's\nfate in life is frequently decided long before birth, and that no amount\nof food or hospital service or culture or tears will ever wholly make good\nthe deficiencies of bad \"blood,\" or in the language of the biologist, a\nfaulty germ-plasm, and the conviction must surely be borne home to the\nintelligent members of society that one thing of superlative importance in\nlife is the making of a wise choice of a marriage mate on the one hand,\nand the prevention of parenthood to the obviously unfit on the other.\n\nIn the present volume it is intended to examine into the natural\nendowment of the child. And since full comprehension of it requires some\nunderstanding of the nature of the physical mechanism by which hereditary\ntraits are handed on from generation to generation, a small amount of\nspace is given to this phase. Then, that the reader may appreciate to\ntheir fullest extent the facts gathered concerning man, a review of the\nmore significant principles of genetics as revealed through experiments in\nbreeding plants and animals has been undertaken. The main applications of\nthese principles to man is pointed out in a general discussion of human\nheredity. Finally, inasmuch as all available data indicate that the fate\nof our very civilization hangs on the issue, the work concludes with an\naccount of the new science of eugenics which is striving for the\nbetterment of the race by determining and promulgating the laws of human\ninheritance so that mankind may intelligently go about conserving good and\nrepressing bad human stocks.\n\nIn order to eliminate as many errors as possible and to avoid oversights I\nhave submitted various chapters to certain of my colleagues and friends\nwho are authorities in the special field treated therein. While these\ngentlemen are in no way responsible for the material of any chapter they\nhave added greatly to the value of the whole by their suggestions and\ncomments. Thus I am indebted to Professor Leon J. Cole for reading the\nentire manuscript; to Professors A. S. Pearse and F. C. Sharp for reading\nChapter VII; to Professor C. R. Bardeen for reading special parts; to\nDoctor J. S. Evans for reading Chapter VI and part of V; to Doctor W. F.\nLorenz, of the Mendota Hospital, for reading Chapter VIII; to Judge E. Ray\nStevens for reading Chapter IX, and to Helen M. Guyer for several readings\nof the entire manuscript.\n\nGrateful acknowledgment is made to all of these readers, to various\npublishers and periodicals for the use of certain of the illustrations, to\nthe authors of the numerous books and papers from which much of the\nmaterial in such a work as this must necessarily be selected, and to my\nartist, Miss H. J. Wakeman, for her painstaking endeavors to make her work\nconform to my ideas of what each diagram should show.\n\nM. F. G.\n\n\n\n\nCONTENTS\n\n\n  CHAPTER                                                             PAGE\n\n  I HEREDITY                                                             1\n\n  Blood heritage--Kind determined by origin--Ancestry a network--\n  Ancestry in royalty--Offspring derived from one parent only--Dual\n  ancestry an aid in studying heredity--Reversion--Telegony--\n  Prenatal influences apart from heredity--Parent body and germ not\n  identical--A hereditary character defined--Hereditary mingling a\n  mosaic rather than a blend--Determiners of characters, not\n  characters themselves, transmitted--Our knowledge of heredity\n  derived along three lines--The method of experimental breeding--\n  The statistical method--Galton's law of regression--Correlations\n  between parents and offspring--The biometrical method,\n  statistical, not physiological--Mental as well as physical\n  qualities inheritable.\n\n\n  II THE BEARERS OF THE HERITAGE                                        20\n\n  The cell the unit of structure--Unicellular organisms--Importance\n  of cell-theory--Heredity in unicellular forms--Reproduction and\n  heredity in colonial protozoa--Conjugation--Specialization of\n  sex-cells--The fertilized ovum--Advancement seen in the Volvox\n  colony--Natural death--Specialization in higher organisms--Sexual\n  phenomena in higher forms--Cell-division--Chromosomes constant in\n  number and appearance--Significance of the chromosomes--Cleavage\n  of the egg--Chief processes operative in building the body--The\n  origin of the new germ-cells--Significance of the early setting\n  apart of the germ-cells--Individuality of chromosomes--Pairs of\n  chromosomes--Reduction of the number of chromosomes by one-half--\n  Maturation of the sperm-cell--Maturation of the egg-cell--Parallel\n  between the two processes--Fertilization--Significance of the\n  behavior of the chromosomes--A single set of chromosomes\n  sufficient for the production of an organism--The duality of the\n  body and the singleness of the germ--The cytoplasm in\n  inheritance--Chromosomes possibly responsible for the\n  distinctiveness of given characters--Sex and heredity--Many\n  theories of sex determination--The sex-chromosome--Sex-linked\n  characters in man--In lower forms.\n\n  III MENDELISM                                                         67\n\n  New discoveries in the field of heredity--Mendel--Rediscovery of\n  Mendelian principles--Independence of inheritable characters--\n  Illustration in the Andalusian fowl--The cause of the ratio--\n  Verification of the hypothesis--Dominant and recessive--\n  Segregation in the next generation--Illustrated in guinea-pigs--\n  Terminology--The theory of presence and absence--Additional\n  terminology--Dominance not always complete--Modifications of\n  dominance--Mendel's own work--Dihybrids--Getting new combinations\n  of characters--Segregations of the determiners--Four kinds of\n  gametes in each sex--The 9:3:3:1 ratio--Phenotype and genotype--\n  The question of blended inheritance--Nilsson-Ehle's discoveries--\n  Such cases easily mistaken for true blends--Skin-color in man--\n  Questionable if real blends exist--The place of the Mendelian\n  factors in the germ-cell--Parallel between the behavior of\n  Mendelian factors and chromosomes--A single chromosome not\n  restricted to carrying a single determiner.\n\n  IV MENDELISM IN MAN                                                   97\n\n  Probably applicable to many characters in man--Difficult to get\n  correct data--A generalized presence-absence formula--Indications\n  of incomplete dominance--Why after the first generation only half\n  the children may show the dominant character--Eye-color in man--\n  Hair-color--Hair-shape--Irregularities--Digital malformations--Eye\n  defects--Other defects inherited as dominants--Recessive\n  conditions more difficult to deal with--Albinism--Other recessive\n  conditions in man--Breeding out defects--Other inheritable\n  conditions in man.\n\n  V ARE MODIFICATIONS ACQUIRED DIRECTLY BY THE BODY INHERITED?         121\n\n  Which new characters are inherited?--Examples of somatic\n  modifications--Use and disuse--The problem stated--Special\n  conditions in mammals--Three fundamental questions--External\n  influences may directly affect the germ-cells--Such effects\n  improbable in warm-blooded animals--Poisons may affect the\n  germ-plasm--How can somatic modifications be registered in\n  germ-cells?--Persistence of Mendelian factors argues against such\n  a mode of inheritance--Experiments on insects--On plants--On\n  vertebrates--Epilepsy in guinea-pigs--Effects of mutilations not\n  inherited--Transplantation of gonads--Effects of body on germ,\n  general not specific--Certain characters inexplicable as inherited\n  somatic acquirements--Neuter insects--Origin of new characters in\n  germinal variation--Sexual reproduction in relation to new\n  characters--Many features of an organism characterized by\n  utility--Germinal variation a simpler and more inclusive\n  explanation--Analysis of cases--Effects of training--Instincts--\n  Disease--Reappearance not necessarily inheritance--Prenatal\n  infection not inheritance--Inheritance of a predisposition not\n  inheritance of a disease--Tuberculosis--Two individuals of\n  tubercular stock should not marry--Special susceptibility less of\n  a factor in many diseases--Deaf-mutism--Gout--Nervous and mental\n  diseases--Other disorders which have hereditary aspects--Induced\n  immunity not inherited--Social, ethical and educational\n  significance of non-inheritance of somatic modifications--No cause\n  for discouragement--Improved environment will help conserve\n  superior strains when they do appear.\n\n  VI PRENATAL INFLUENCES                                               151\n\n  All that a child possesses at birth not necessarily hereditary--\n  The myth of maternal impressions--Injurious prenatal influences--\n  Lead poisoning--The expectant mother should have rest--Too short\n  intervals between children--Expectant mothers neglected--\n  Alcoholism--Unreliability of most data--Alcohol a germinal and\n  fetal poison--Various views of specialists on the effects of\n  alcoholism on progeny--The affinity of alcohol for germinal\n  tissue--Innate degeneracy versus the effects of alcohol--\n  Experimental alcoholism in lower animals--Further remarks on the\n  situation in man--Much inebriety in man due to defective nervous\n  constitution--Factors to be reckoned with in the study of\n  alcoholism--Venereal diseases--The seriousness of the situation--\n  Infantile blindness--Syphilis--Some of the effects--A blood test--\n  Many syphilitics married--Why permit existing conditions to\n  continue?--Ante-nuptial medical inspection--The perils of venereal\n  disease must be prevented at any cost--Bad environment can wreck\n  good germ-plasm.\n\n  VII RESPONSIBILITY FOR CONDUCT                                       195\n\n  All mental process accompanied by neural process--Gradations in\n  nervous response from lower organisms to man--Behavior of many\n  animals often an automatic adjustment to simple external agents--\n  Tropisms--Certain apparently complex volitions probably only\n  tropisms--Complicating factors--Many tropic responses apparently\n  purposeful--Tropisms grade into reflex actions and instincts--\n  Adjustability of instincts opens the way for intelligent\n  behavior--Modification of habits possible in lower animals--Some\n  lower vertebrates profit by experience--Rational behavior--\n  Conceptual thought probably an outgrowth of simpler psychic\n  states--The capacity for alternative action in higher animals--The\n  elemental units of the nervous system are the same in lower and\n  higher animals--Neuron theory--Establishment of pathways through\n  the nervous system--Characteristic arrangements of nerve cells\n  subject to inheritance--Different parts of the cortex yield\n  different reactions--Skill acquired in one branch of learning\n  probably not transferred to another branch--Preponderance of\n  cortex in highest animals--Special fiber tracts in the spinal cord\n  of man and higher apes--Great complexity in associations and more\n  neurons in the brain of man--The nervous system in the main\n  already staged at the time of birth--Many pathways of conduction\n  not yet established--The extent of the modifiable zone unknown--\n  Various possibilities of reaction in the child--Probable origin of\n  altruistic human conduct--Training in motive necessary--Actual\n  practise in carrying out projects important--Interest and\n  difficulty both essential--The realization of certain\n  possibilities of the germ rather than others is subject to\n  control--We must afford the opportunity and provide the proper\n  stimuli for the development of good traits--Moral responsibility.\n\n  VIII MENTAL AND NERVOUS DEFECTS                                      228\n\n  Prevalence of insanity--Imperfect adjustments of the brain\n  mechanism inheritable--Many mental defectives married--\n  Disproportionate increase in number of mental defectives--Protests\n  voiced by alienists--Examples of hereditary feeble-mindedness--\n  Difficult to secure accurate data--Feeble-mindedness and insanity\n  not the same--Many types of insanity--Not all insanities of the\n  same eugenical significance--Difficulties of getting genealogies\n  of specific forms of insanity--Certain forms of insanity seem to\n  behave as Mendelian recessives--Grades of feeble-mindedness--About\n  two-thirds of feeble-mindedness inherited--Some results of\n  non-restraint of the feeble-minded--Not all cases of mental\n  deficiency inherited--Epileptics--Feeble-mindedness probably a\n  recessive--Many apparently normal people are carriers of\n  neuropathic defects--Tests for mental deficiency--The backward\n  child in school--The exceptionally able child--Cost of caring for\n  our mentally disordered--Importance of rigid segregation of the\n  feeble-minded--Importance of early diagnosis of insanity--Opinion\n  of competent psychiatrists essential--Some insanities not\n  hereditary--Importance of heredity in insanity not appreciated.\n\n  IX CRIME AND DELINQUENCY                                             263\n\n  Heredity and environment in this field--Feeble-mindedness often a\n  factor--Many delinquent girls mentally deficient--Institutional\n  figures misleading--Many prisoners mentally subnormal--Inhibitions\n  necessary to social welfare--The high-grade moron a difficult\n  problem--Degenerate strains--Intensification of defects by\n  inbreeding--Vicious surroundings not a sufficient explanation in\n  degenerate stocks--Not all delinquents defectives--No special\n  inheritable crime-factor--What is a born criminal?--Epileptic\n  criminal especially dangerous--The mental disorders most\n  frequently associated with crime--Bearing of immigration on crime\n  and delinquency--Sexual vice--School instruction in sex-hygiene--\n  Mere knowledge not the crux of the sex problem--Early training in\n  self-restraint an important preventive of crime and delinquency--\n  Multiplication of delinquent defectives must be prevented.\n\n  X RACE BETTERMENT THROUGH HEREDITY                                   289\n\n  Questionable charity--Past protests--An increasing flood of\n  defectives--Natural elimination of defectives done away with--Why\n  not prevent our social maladies?--Eugenics defined--Improved\n  environment alone will not cure racial degeneracy--Heredity and\n  environment--Inter-racial marriage--Human conservation--Kindness\n  in the long run--The problem has two phases--Constructive eugenics\n  must be based on education--Inferior increasing more rapidly than\n  superior stocks--An unselected population may contain much\n  valuable material--The lack of criteria for judging fitness--The\n  college graduate--Native ability, independence and energy\n  eugenically desirable--Four children to each marriage required to\n  maintain a stock--Factors contributing to low birth-rate in\n  desirable strains--The educated public must be made to realize the\n  situation--Utilization of family pride as a basis for constructive\n  eugenics--The tendency for like to marry like--Public opinion as\n  an incentive to action--Choosing a marriage mate means choosing a\n  parent--The best eugenic marriage also a love match--The\n  elimination of the grossly unfit urgent--Suggested remedies--\n  Inefficacy of laws which forbid marriage of mental defectives--\n  Systems of mating impracticable in the main--Corrective mating\n  presupposes knowledge of eugenics--Segregation has many\n  advocates--Sterilization as a eugenic measure--To what conditions\n  applicable--In insanity--In feeble-mindedness--In cases of\n  epilepsy--Sterilization laws--Social dangers in vasectomy--Our\n  present knowledge insufficient--Sterilization laws on trial--An\n  educated public sentiment the most valuable eugenic agent--The\n  question of personal liberty--Education of women in eugenics\n  needed--Much yet to be done--A working program--Which shall it be?\n\n  GLOSSARY                                                             343\n\n  REFERENCES FOR FURTHER READING AND STUDY                             355\n\n  INDEX                                                                361\n\n\n\n\nBEING WELL-BORN\n\n\n\n\nCHAPTER I\n\nHEREDITY\n\n\nIt is a commonplace fact that offspring tend to resemble their parents. So\ncommonplace, indeed, that few stop to wonder at it. No one misunderstands\nus when we say that such and such a young man is \"a chip off the old\nblock,\" for that is simply an emphatic way of stating that he resembles\none or the other of his parents. The same is true of such familiar\nexpressions as \"what's bred in the bone,\" \"blood will tell,\" and kindred\ncatch phrases. All are but recognitions of the same common fact that\noffspring exhibit various characteristics similar to those of their\nprogenitors.\n\n=Blood Heritage.--=To this phenomenon of resemblance in successive\ngenerations based on ancestry the term heredity is applied. In man, for\ninstance, there is a marked tendency toward the reappearance in offspring\nof structures, habits, features, and even personal mannerisms, minute\nphysical defects, and intimate mental peculiarities like those possessed\nby their parents or more remote forebears. These personal characteristics\nbased on descent from a common source are what we may call the blood\nheritage of the child to discriminate it from a wholly different kind of\ninheritance, namely, the passing on from one generation to the next of\nsuch material things as personal property or real estate.\n\n=Kind Determined by Origin.--=It is inheritance in the sense of community\nof origin that determines whether a given living creature shall be man,\nbeast, bird, fish, or what not. A given individual is human because his\nancestors were human. In addition to this stock supply of human qualities\nhe has certain well-marked features which we recognize as characteristics\nof race. That is, if he is of Anglo-Saxon or Italian or Mongolian\nparentage, naturally his various qualities will be Anglo-Saxon, Italian,\nor Mongolian. Still further, he has many distinctive features of mind and\nbody that we recognize as family traits and lastly, his personal\ncharacteristics such as designate him to us as Tom, Harry, or James must\nbe added. The latter would include such minutiae as size and shape of ears,\nnose or hands; complexion; perhaps even certain defects; voice; color of\neyes; and a thousand other particulars. Although we designate these\nmanifold items as individual, they are in reality largely more or less\nduplicates of similar features that occur in one or the other of his\nprogenitors, features which he would not have in their existing form but\nfor the hereditary relation between him and them.\n\n  \"O Damsel Dorothy! Dorothy Q.!\n  Strange is the gift that I owe to you;\n\n    *       *       *       *       *\n\n  What if a hundred years ago\n  Those close-shut lips had answered 'No,'\n\n    *       *       *       *       *\n\n  Should I be I, or would it be\n  One-tenth another, to nine-tenths me?\"\n\n  \"Soft is the breath of a maiden's yes;\n  Not the light gossamer stirs with less;\n  But never a cable that holds so fast\n  Through all the battles of wave and blast,\n  And never an echo of speech or song\n  That lives in the babbling air so long!\n  There were tones in the voice that whispered then\n  You may hear to-day in a hundred men.\"\n\nWhen life steps into the world of matter there comes with it a sort of\nphysical immortality, so to speak; not of the individual, it is true, but\nof the race. But the important thing to note is that the race is made up,\nnot of a succession of wholly unrelated forms, but a continuation of the\nsame kind of living organisms, and this sameness is due to the actual\nphysical descent of each new individual from a predecessor. In other\nwords, any living organism is the kind of organism it is in virtue of its\nhereditary relation to its ancestors.\n\nIt is part of the biologist's task to seek a material basis, a continuity\nof actual substance, for this continuity of life and form between an\norganism and its offspring. Moreover, inasmuch as the offspring is never\nprecisely similar to its progenitors he must determine also what qualities\nare susceptible of transmission and in what measure.\n\n=Ancestry a Network.--=From the fact that each child has all of the\nancestors of its mother as well as of its father, arises the great\ncomplications which are met with in determining the lineage of an\nindividual. A person has two parents, four grandparents, eight great\ngrandparents, and thus following out pedigree it is plain to be seen that\nthrough this process of doubling in each generation, in the course of a\nfew centuries one's ancestry is apparently enormous. By actual\ncomputation, according to Professor D. S. Jordan, if we count thirty\ngenerations back to the Norman invasion of England in 1066, at this ratio\nof duplication, the child of to-day would have had at that time an\nancestry of 8,598,094,592 persons. But we know that the total number of\ninhabitants in England during the time of William the Conqueror was but a\nsmall fraction of this enormous aggregate. This means that we shall have\nto modify our inference that a child has twice as many ancestors as its\nparents; a condition which at first sight seems evident, but which is not\nliterally true. The fact is that the parents of the child, in all\nprobability, have many ancestors in common--a state of affairs which is\nbrought about through the intermarriage of relatives, and this is\nespecially frequent among remoter descendants of common progenitors. Time\nafter time in genealogy strains of blood have crossed and recrossed until\nit is not improbable that a man of to-day who is of English origin has the\nblood in his veins from every inhabitant of England who lived during the\ntime of William the Conqueror and left fruitful descendants. Instead of\nconceiving of ancestry as an ever branching and widening tree-like system\nas it recedes into the past, it is more accurate, therefore, to regard it\nin the light of an elaborate meshwork. The \"family tree\" in reality\nbecomes the family net.\n\n=Ancestry in Royalty.--=The pedigrees of royal families have proved to be\nof much importance in the study of human inheritance, not that royal\ntraits are any more heritable than any other, but simply because the\nrecords have been carefully kept so that they are the most comprehensive\nand easily followed pedigrees available. The netlike weave of ancestry is\nparticularly well exemplified in some of these families because of much\nclose intermarriage. Their heritage typifies on an intensified scale the\nheritage of the mass of mankind. For example, if we go six generations\nback in the ancestry of Frederick the Great instead of the expected\nsixty-four individual ancestors we find only forty; or in a still more\nclosely woven stock, in the Spanish royal line of Don Carlos we find in\nsix generations instead of sixty-four individual ancestors, only\ntwenty-eight. While the present German emperor might have had four\nthousand ninety-six ancestors in the twelfth generation back, it is\nestimated that owing to intermarriage he probably had only five hundred\nthirty-three.\n\n=Offspring Derived from One Parent Only.--=So far in our reckoning of\nheredity we have counted elements from both father and mother, and the\ncomplications which arise from such a double ancestry are manifestly very\nperplexing ones. If we could do away with the elements of sex and find\noffspring that are derived from one parent only, it would seemingly\nsimplify our problem very much for we should thus have a direct line of\ndescent, free from intermingling. This, in fact, occurs to a greater or\nless extent among lower animals in a number of instances. There may be\nonly female forms for a number of generations and the eggs which they\nproduce develop directly into new individuals. Moreover, many of the\nsimpler organisms have the power of dividing their bodies into two and\nthus giving rise to two new forms, each of which resembles the parent.\nThis shows plainly that we may have inheritance without the appearance of\nany male ancestor at all, hence sex is not always a necessary factor in\nreproduction or heredity. The development of eggs asexually, that is,\nwithout uniting first with a male cognate, is termed _parthenogenesis_.\nThe ordinary plant louse or aphid which is frequently found upon geraniums\nis a familiar example of an animal which reproduces largely in this way.\nDuring the summer only the females exist and they are so astonishingly\nfertile that one such aphid and her progeny, supposing none dies, will\nproduce one hundred million in the course of five generations. In the last\nbroods of the fall, males and females appear and fertile eggs are produced\nwhich lie dormant through the winter to start the cycle of the next year.\nAgain, the eggs of some kinds of animals which normally have to unite with\na male germ before they develop, can be made to develop by merely treating\nthem with chemical solutions. The difference between an offspring derived\nin such a manner, and one which has developed from an egg fertilized by\nthe male is that it is made up of characteristics from only one source,\nthe maternal.\n\n=Dual Ancestry an Aid in Studying Heredity.--=Although we have the factors\nof heredity in a more simplified form in the case of asexual\ntransmission, as a matter of fact most of our insight into the problems\nof heredity has been attained from a study of sexually reproducing forms,\nbecause the very existence of two sets of more or less parallel features\noffers a kind of checking up system by which we can follow a given\ncharacteristic.\n\n=Reversion.--=Occasionally, however, plants and animals do not develop the\ncomplete individuality we might expect, but stop short at or re-attain\nsome ancestral stage along the line of descent, and thus come to resemble\nsome progenitor perhaps many generations back of their own time. Thus it\nis well known that as regards one or more characteristics a child may\nresemble a grandparent or often some remote ancestor much more closely\nthan it does its immediate parent. The reappearance of such ancestral\ntraits the student of heredity designates as _Reversion_ or _Atavism_.\n\nReversion may occur apparently in any class of plants or animals. It is\nespecially pronounced among domesticated forms, which through man's\nselection have been produced under more or less artificial conditions. For\nexample, among fancy breeds of pigeons, there may be an occasional return\nto the old slaty blue color of the ancestral rock-pigeon, with two dark\ncross-bars on the wings, from which all modern breeds have been derived.\nThis is almost sure to happen if the fancy varieties are inter-crossed for\ntwo or three generations. Another example of reversion frequently cited is\nthe occasional reappearance in domestic poultry of the reddish or brownish\ncolor pattern of the ancestral jungle-fowl to which, among modern forms,\nthe Indian game seems most nearly related in color. Still another example\nis the cross-bars or stripes occasionally to be seen on the forelegs of\ncolts, particularly mules, reminiscent of the extinct wild progenitors\nwhich were supposedly striped.\n\nFig. 1, p. 9, is a picture of a hybrid between the common fowl and the\nguinea-fowl. The chevron-like markings on certain feathers show a\nreversion to a type of color pattern that is prevalent among both the\nprimitive pheasants (the domestic chicken is a pheasant) and the primitive\nguinea-fowls. Although the common spotted guinea-fowl may be crossed with\na black chicken which shows no trace of barring, nevertheless the hybrid\noffspring are likely to bear a chevron-like pattern such as that shown in\nthe picture.\n\nThere has been much quibbling over the relative meanings of reversion and\natavism. The general idea, whichever term we use, is that there is a\n\"throwing back\" in a noticeable degree through inheritance to some\nancestral condition beyond the immediate parents. A few recent authors\nhave taken the term atavism in a restricted sense and use it to signify\nspecifically those not uncommon cases in which a particular character of\nan offspring resembles the corresponding character of a grandparent\ninstead of a parent. Such, for example, as the blue eye-color of a child\nwith brown-eyed parents, each of whom in turn has had a blue-eyed parent.\nThe tendency of other authors is to abandon the term entirely because of\nthe diversity of meaning that has been attached to it in the past.\n\n\n[Illustration: FIG. 1\n\nHybrid between the guinea-fowl and the common fowl, showing in many\nfeathers reversion to a primitive chevron-like barring.]\n\n\nCertain classes of so-called reversions, such as the case of the eye-color\njust cited, are readily explicable on Mendelian principles as we shall see\nin a later chapter, but probably not all kinds of phenomena described as\nreversion can be so explained. For example, some seem to be cases of\nsuppressed development. The word reversion, indeed, must be looked on as\na convenient descriptive term rather than as the name of a single specific\ncondition.\n\n=Telegony.--=There is yet a wide-spread belief in the supposed influence\nof an earlier sire on offspring born by the same mother to a later and\ndifferent sire. This alleged phenomenon is termed _telegony_. For example,\nmany dog-breeders assert that if a thoroughbred bitch has ever had pups by\na mongrel father, her later offspring, although sired by a thoroughbred,\nwill show taints of the former mongrel mating. In such cases the female is\nbelieved to be ruined for breeding purposes. Other supposed instances of\nsuch influences have been cited among horses, cattle, sheep, pigs, cats,\nbirds, pets of various kinds and even men. The historic case most\nfrequently quoted is that of Lord Morton's mare which bore a hybrid colt\nwhen bred to a quagga, a striped zebra-like animal now extinct. In later\nyears the same mare bore two colts, sired by a black Arabian horse. Both\ncolts showed stripes on the neck and other parts of the body, particularly\non the legs. It was inferred that this striping was a sort of after effect\nof the earlier breeding with the quagga. In recent times, however,\nProfessor Ewart has repeated the experiment a number of times with\ndifferent mares using a Burchell zebra as the test sire. Although his\nexperiments have been devised so as to conduce in every way possible to\ntelegony his results have been negative. Moreover, it has been pointed out\nthat the stripes on the legs of the two foals alleged to show telegony\ncould not have been derived from the quagga sire for, unlike zebras,\nquaggas did not have their legs striped. Furthermore it is known that the\noccurrence of dark brown stripes on the neck, withers and legs of ordinary\ncolts is not uncommon, some cases of which have exhibited more zebra-like\nmarkings than those of the colts from Lord Morton's mare. It seems much\nmore probable, therefore, that the alleged instances are merely cases of\nordinary reversion to the striped ancestral color pattern which probably\ncharacterized the wild progenitors of the domesticated horse.\n\nVarious experiments on guinea-pigs, horses, mice and other forms,\nespecially devised to test out this alleged after-influence of an earlier\nsire, have all proved negative and the general belief of the biologist\nto-day is that telegony is a myth.\n\n=Prenatal Influences Apart from Heredity.--=In discussing the problems of\nheredity it is necessary to consider also the possibilities of external\ninfluences apart from lineage which may affect offspring through either\nparent. Although modifications derived directly by the parent, and\nprenatal influences in general, are of extremely doubtful value as of\npermanent inheritable significance, nevertheless they must be reckoned\nwith in any inventory of a child's endowment at birth. Impaired vitality\non the part of the mother, bad nutrition and physical vicissitudes of\nvarious kinds all enter as factors in the birthright of the child, who,\nmoreover, may bear in its veins slumbering poisons from some progenitor\nwho has handed on blood taints not properly attributable to heredity. Of\nsuch importance is this kind of influence to the welfare of the immediate\nchild that it will be necessary to discuss it in considerable detail in a\nlater chapter.\n\n=Parent Body and Germ Not Identical.--=Inasmuch as each new individual\nappears to arise from material derived from its parent, taking the\nevidence at its face value one might suppose that any peculiarity of\norganization called forth in the living substance of the parent would\nnaturally be repeated in the offspring, but a closer study of the\ndeveloping organism from its first inception to maturity shows this to be\nprobably a wrong conclusion. The parent-body and the reproductive\nsubstance contained in that body are by no means identical. It becomes an\nimportant question to decide, in fact, how much effect, if any, either\npermanent or temporary, the parent-body really has on the germ.\n\nA given fertile germ (Fig. 2, p. 13) gives rise by a succession of\ndivisions to a body which we call the individual, but such a germ also\ngives rise to a series of new germ-cells which reside in that individual,\nand it is these germ-cells, not something derived from the body, that pass\non the determiners of distinguishing features or qualities from generation\nto generation. It is only by grasping the significance of this fact that\nwe can understand how in certain cases a totally different set of\ncharacters may appear in an offspring than those manifested in either\nparent.\n\n=An Hereditary Character Defined.--=By a _character_, in discussions in\nheredity, is meant simply a trait, feature or other characteristic of an\norganism. Where we can pick out a single definable characteristic which\nacts as a unit in heredity, for greater accuracy we term it a\n_unit-character_. Many traits are known to be inherited on a unit basis or\nare capable of being analyzed into factors which are so inherited. These\nunit-characters are in large measure inherited independently of one\nanother apparently, although cases of characters inherited as a unit along\nwith other characters are known.\n\n=Hereditary Mingling a Mosaic Rather Than a Blend.--=The independence of\nunit-characters in inheritance leads us to the important conclusion that\nthe mingling of two lines of ancestry into a new individual is in no sense\nbringing them into the \"melting pot,\" as it has been picturesquely\nexpressed, but it is rather to be regarded as the mingling of two mosaics,\neach particle of which retains its own individuality, and which, even if\novershadowed in a given generation, may nevertheless manifest its\nqualities undimmed in later generations when conditions favorable to its\nexpression transpire.\n\n\n[Illustration: FIG. 2\n\nDiagram illustrating germinal continuity. Through a series of divisions a\ngerm-cell gives rise to a body or a soma and to new germ-cells. The\nlatter, not the body, give rise in turn to the next generation.]\n\n\n=Determiners of Characters, Not Characters Themselves, Transmitted.--=The\nfact should be thoroughly understood that the actual thing which is\ntransmitted by means of the germ in inheritance is not the character\nitself, but something which will _determine_ the character in the\noffspring. It is important to remember this, for often these\n_determiners_, as they are called, may lie unexpressed for one or more\ngenerations and may become manifest only in later descendants. The truth\nof the matter is, the child does not inherit its characters from\ncorresponding characters in the parent-body, but parent and child are\nalike because they are both products of the same line of germ-plasm, both\nare chips from the same old block.\n\n\nMETHODS OF STUDYING HEREDITY\n\nBefore entering into details it will be well to get some idea of the\nmethods which are commonly employed in arriving at conclusions in the\nfield of heredity. Some of these are extremely complex and all that we can\ndo in an elementary presentation is to get a glimpse of the procedures.\n\n=Our Knowledge of Heredity Derived Along Three Lines.--=Our modern\nconceptions of heredity have been derived mainly from three distinct lines\nof investigation: First, from the study of embryology, in which the\nbiologist concerns himself with the genesis of the various parts of the\nindividual, and the mechanism of the germs which convey the actual\nmaterials from which these parts spring; second, through experimental\nbreeding of plants and animals to compare particular traits or features in\nsuccessive generations; and third, through the statistical treatment of\nobservations or measurements of a large number of parents and their\noffspring with reference to a given characteristic in order to determine\nthe average extent of resemblance between parents and children in that\nparticular respect.\n\n=The Method of Experimental Breeding.--=A tremendous impetus was given to\nthe method of experimental breeding when it was realized that we can\nitemize many of the parts or traits of an organism into entities which are\ninherited independently one of another. Such traits, or as we have already\ntermed them, unit-characters, may be not only independently heritable but\nindependently variable as well. The experimental method seeks to isolate\nand trace through successive generations the separate factors which\ndetermine the individual unit-characters of the organism. In this attempt\ncross-breeding is resorted to. Forms which differ in one or more respects\nare mated and the progeny studied. Next these offspring are mated with\nothers of their own kind or mated back with the respective parent types.\nIn this way the behavior of a particular character may often be followed\nand the germinal constitutions of the individuals concerned can be\nformulated with reference to it. Inasmuch as we shall give much\nconsideration to this method in the chapter on Mendelism we need not\nconsider it further here.\n\n=The Statistical Method.--=The statistical method seeks to obtain large\nbodies of facts and to deal with evidence as it appears through\nmathematical analysis of these facts. The attempt of its followers is to\ntreat quantitatively all biological processes with which it is concerned.\nHistorically Sir Francis Galton was the first to make any considerable\napplication of statistical methods to the problems of heredity and\nvariation. In his attempts to determine the extent of resemblance between\nrelatives of different degree as regards bodily, mental and temperamental\ntraits, he devised new methods of statistical analysis which constitute\nthe basis of modern statistical biology, or _biometry_ as it is termed by\nits votaries. Professor Karl Pearson in particular has extended and\nperfected the mathematical methods of this field and stands to-day as\nperhaps its most representative exponent. The system is in the main based\non the calculus of probability. The methods often are highly specialized,\nrequiring the use of higher mathematics, and are therefore only at the\ncommand of specially trained workers.\n\nJust as insurance companies can tell us the probable length of human life\nin a given social group, since although uncertain in any particular case,\nit is reducible in mass to a predictable constant, so the biometrician\nwith even greater precision because of his improved methods can often,\nwhen a large number of cases are concerned, give us the intensity of\nancestral influence with reference to particular characters.\n\nFor example, it is clear that by measuring a large number of adult human\nbeings one can compute the average height or determine the height which\nwill fit the greatest number. There will be some individuals below and\nsome above it, but the greater the divergence from this standard height\nthe fewer will be the individuals concerned.\n\nGalton compared the heights of 204 normal English parents and their 928\nadult offspring. In order to equalize the measurements of men and women he\nfound he had to multiply each female height by 1.08. Then, to take both\nparents into account when comparing height of parents to that of children\nhe added the height of the father to the proportionately augmented height\nof the mother and divided by two, thus securing the height of what he\ntermed the \"mid-parent.\" He found that the mid-parental heights of his\nsubjects ranged from 64.5 to 72.5 inches, and that the general _mode_ was\nabout 68.5 inches. It should be mentioned that the _mode_, in a given\npopulation, represents the group containing the largest number of\nindividuals of one kind; it may or may not coincide with the average. The\nchildren of all mid-parents having a given height were measured next and\ntabulated with reference to these mid-parents. The results of Galton's\nmeasurements may be expressed simply as follows:\n\n  -----------------------------------------------------------------\n                                          |MODE|\n  ----------------------------------------|----|-------------------\n  Height of mid-parent|    |    |    |    |    |    |    |    |\n  in inches           |64.5|65.5|66.5|67.5|68.5|69.5|70.5|71.5|72.5\n                      |    |    |    |    |    |    |    |    |\n  Average height of   |    |    |    |    |    |    |    |    |\n  offspring           |65.8|66.7|67.2|67.6|68.3|68.9|69.5|69.9|72.2\n  -----------------------------------------------------------------\n\n=The Law of Regression.--=It is plain from this table that the offspring\nof short mid-parents tend to be under average or modal height though not\nso far below as their parents. Likewise children of tall parents tend to\nbe tall but less tall than their parents. This fact illustrates what is\nknown as Galton's _law of regression_; namely, that if parents in a given\npopulation diverge a certain amount from the mode of the population as a\nwhole, their children, while tending to resemble them, will diverge less\nfrom this mode. It is clear that the extent of regression is an inverse\nmeasure of the intensity of inheritance from the immediate parents; if the\ndeviation of the offspring from the general mode were nearly as great as\nthat of their parents then the intensity of the inheritance must be high;\nif but slight--that is, if the offspring regressed nearly to the\nmode--then the intensity of the inheritance must be ranked as low. In the\nexample in question it must be ranked as relatively high. Computations\nshow that as regards stature the fraction two-thirds represents\napproximately the amount of resemblance between the two generations where\nboth parents are considered.\n\n=Correlations Between Parents and Offspring.--=In modern researches the\nconception of mid-parent and mid-grandparent as utilized by Galton has\nbeen largely abandoned. It has been found more convenient as well as more\naccurate to keep the measurements of the two parents separate and to deal\nwith correlations between fathers and sons, fathers and daughters, mothers\nand sons, mothers and daughters, brother and brother, etc. Professor\nPearson and his pupils have found for a number of characters that the\ncorrelation between either parent and children, whether sons or daughters,\nis relatively close. The correlation between brother and brother, sister\nand sister, and brother and sister, usually ranges a little higher than\nthe corresponding relation between parents and children.\n\n=The Biometrical Method, Statistical, Not Physiological.--=While biometry\nmay in certain cases go far toward showing us the average intensity of\nthe inheritance of certain characters it can not replace the method of\nthe experimental breeder which deals with particular characters in\nindividual pedigrees. It must be borne in mind that the biometrical method\nis a statistical and not a physiological one and that it is applicable\nonly when large numbers of individuals are considered in mass. It is most\nvaluable in cases where we are unable sharply to define single characters,\ndue probably to the concurrent action of a number of independent causes,\nor where experiment is impossible so that we have to depend solely on\nnumerical data gained by observation.\n\n=Mental Qualities Inheritable.--=Galton showed by this method long ago,\nand Pearson and his school have extended and more clearly established the\nwork, that exceptional mental qualities tend to be inherited. While on the\naverage the children of exceptional parents tend to be less exceptional\nthan their parents, still they are far more likely to be exceptional than\nare the children of average parents. By this method Professor Pearson has\nshown that such mental and temperamental attributes as ability, vivacity,\nconscientiousness, temper, popularity, handwriting, etc., are as\nessentially determined as are physical features through the hereditary\nendowment.\n\n\n\n\nCHAPTER II\n\nTHE BEARERS OF THE HERITAGE\n\n\nBefore we can make any detailed analysis of the inheritance of characters\nwe should have some general idea of the physical structure of animals and\nparticularly some familiarity with the development of an individual from\nthe egg, as well as some knowledge of the nature of the germ-cells.\n\n=The Cell the Unit of Structure.--=If we examine one of the higher\nanimals, as, for example, the horse, the dog, or man, we find that it is\nmade up of a large number of constituents, such as bones, muscles, nervous\nelements, blood and other tissues. Each kind of tissue is composed of a\nnumber of living units, ordinarily microscopic in size, which are known as\ncells. A careful examination of various cells reveals that although they\nmay differ greatly in size, shape and minor details, they all alike\npossess certain well-marked characteristics. Each when reduced to its\nfundamental form is seen to consist of a small mass of living matter\ntermed protoplasm in which may usually be distinguished two regions--the\ncell-body or _cytoplasm_, and the _nucleus_ (Fig. 3, p. 21). Any cell,\nwhether it be of the brain, of the liver, or from any organ of an animal\nor plant, has this same fundamental structure. In addition, a limiting\nmembrane or wall of some kind is generally present, although it is not a\nnecessary constituent of all cells.\n\n\n[Illustration: FIG. 3\n\nDiagram of a cell showing various parts.]\n\n\n=Unicellular Organisms.--=While such a structure as a tree or a horse is\ncomposed of countless millions of cells, on the other hand numerous\norganisms, both plant and animal, exist which consist of only one cell.\nYet this cell is just as characteristically a cell as are the components\nof a complex animal or plant. It has the necessary parts, the cell body\nand the nucleus. Moreover it exhibits all of the fundamental activities of\nlife, though in a simplified form, that a complex higher organism does.\n\n=Importance of Cell-Theory.--=This discovery that every living thing is a\nsingle cell or an aggregation of cooperating cells and cell-products is\none of our most important biological generalizations because it has\nbrought such a wide range of phenomena under a common point of view. In\nthe first place, the structure of both plants and animals is reducible to\na common fundamental unit of organization. Moreover, both physiological\nand pathological phenomena are more readily understood since we recognize\nthat the functions of the body in health or disease are in large measure\nthe result of the activities of the individual cells of the functioning\npart. Then again, the problems of embryological development have become\nmuch more sharply defined since it could be shown that the egg is a single\ncell and that it is through a series of divisions of this cell and\nsubsequent changes in the new cells thus formed that the new organism is\nbuilt up. And lastly, the problem of hereditary transmission has been\nrendered more definite and approachable by the discovery that the male\ngerm is likewise a single cell, that fertilization of the egg is therefore\nthe union of two cells, and that in consequence the mechanism of\ninheritance must be stowed away somehow in these two cells.\n\n=Heredity in Unicellular Forms.--=In unicellular animals one can readily\nsee how it is possible for an individual always to give rise to its own\nkind. One of the simplest of the single-celled animals is the _Ameba_\n(Fig. 4, p. 24).\n\nThe ameba eats and grows as do other animals. Sooner or later it reaches a\nsize beyond which it can not increase advantageously, yet it is\ncontinuously taking in new food material which stimulates it to further\ngrowth. Here then is a problem. The ameba solves this difficulty by\ndividing to form two amebae. Such a division is illustrated in Fig. 4, p.\n24. First the nucleus divides, then the cell-body. When the two new amebae\nseparate completely each renews the occupation of eating and growing. But\nwhat has become of the parent? Here, where once existed a large adult\nameba are two young amebae. The parent individual as such has disappeared,\nyet there has been no death, for we have simply two bits of living jelly\nin place of one. They will in turn repeat the same process, so will their\noffspring, and thus, barring accident, this growth and reproduction, or\novergrowth as we may regard it, may go on forever, as far as we know. Here\nthe problem of heredity, or the resemblance of offspring to parent, is not\na very complicated one. The substance of the cell-body and cell-nucleus\ndivides into two similar halves, so that each descendant has the substance\nof the parent in its own body, only it has but half as much. It differs\nfrom the parent, not in quality or kind, but in size.\n\n\n[Illustration: FIG. 4\n\nSix successive stages in the division of _Ameba polypodia_ (after\nSchulze). The nucleus is seen as a dark spot in the interior.]\n\n\n=Reproduction and Heredity in Colonial Protozoa.--=There are enormous\nnumbers of these single-celled animals existing in all parts of the world.\nSome are simple like the ameba, others are very complex in structure.\nMany, after division, move apart and pursue wholly independent courses of\nexistence. On the other hand we find a modification appearing in some\nwhich is of the greatest importance. After division instead of moving\napart the two cells may remain side by side and divide further to form\ntwo more, these in turn may divide and thus the process goes on until\nthere is formed what is known as a colony. Each cell of such a colony\nresembles the original ancestral cell because each is a part of the actual\nsubstance of that cell. As in the ameba, the first two cells are the\nancestral cell done up in two separate packets, and thus finally the full\nquota of cells must be so many separate packets of the same kind of\nmaterial. Inasmuch as each is but a repetition of its original ancestor,\nit can, and at times does, produce a colony of the same kind as that\nancestor produced.\n\n=Conjugation.--=At longer or shorter intervals, however, we find that two\nindividuals, on the disruption of the old colony, instead of continuing\nthe routine of establishing new colonies through a series of cell\ndivisions, very radically alter their behavior. They unite and fuse into a\nsingle larger individual. This process is called _conjugation_. We find it\noccurring even in some species of ameba. The conjugating cells in some\ncolonies are alike in size and appearance, in others different.\n\n=Specialization of Sex-Cells.--=A beautiful sphere-shaped colony known as\n_Volvox_ is to be found occasionally in roadside pools. Depending on the\nspecies of _Volvox_ to which it belongs, the colony may be made up of from\na few hundred to several thousand individuals arranged in a single layer\nabout the fluid-filled center of the sphere and bound together by a clear\njelly-like inter-cellular substance. Each individual cell also connects\nwith its neighbors by means of thin threads of living matter. One of the\nlargest species is _Volvox globator_, one edge of which is represented in\nFig. 5, p. 27. Mutual pressure of the cells gives them a polygonal shape\nwhen viewed from the surface. Each cell, with a few exceptions to be noted\nimmediately, bears two long flagella, whip-like structures which project\nout into the water. The lashing of these flagella gives the ball a rotary\nmotion and thus it moves about. When the colony has reached its adult\ncondition and is ready to reproduce itself, certain cells without flagella\nand somewhat larger than the ordinary cells become more rounded in outline\nand increase considerably in size through the acquisition of food\nmaterials. They are then known as egg cells or ova. Each ovum finally\nenters on a series of cell-divisions forming a mass of smaller and smaller\ncells which gradually assumes the form of a hollow sphere like the parent\ncolony. The young colonies thus formed drop into the interior of the\nparent colony to escape later to the outside as independent swimming\norganisms when the old colony dies and disintegrates.\n\n=The Fertilized Ovum Termed a Zygote.--=After a number of generations of\nsuch asexual reproduction, sexual reproduction occurs. The ova arise as\nusual. Certain members of the colony, on the other hand, go to the other\nextreme and divide up into bundles of from sixty-four to one hundred\ntwenty-eight minute slender cells, each provided with flagella for\nlocomotion. When mature these small flagellate cells, now known as\n_spermatozoa_, escape into the interior of the parent colony and swim\nabout actively. Ultimately each ovum is penetrated by a spermatozoon, the\ntwo cells fuse completely and thus form the single _fertilized ovum_ or\n_zygote_. The body-cells of the mother colony finally disintegrate. After\na period of rest each zygote, through a series of cell-divisions, develops\ninto an adult Volvox. In some species of Volvox a still further advance is\nseen, in that instead of both kinds of gametes being produced in the same\ncolony, the ova may be produced by one colony and the spermatozoa by\nanother. Here, then, we have the foreshadowings of two sexes as separate\nindividuals, a phenomenon of universal occurrence among the highest forms\nof animal life.\n\n\n[Illustration: FIG. 5\n\n_Volvox globator_ (from Hegner after Oltmanns). Half of a sexually\nreproducing colony: _o_, eggs; _s_, spermatozoa.]\n\n\n=Advancement Seen in the Volvox Colony.--=In the Volvox colony there is a\ndistinct advance over the conditions met with in various lower protozoan\ncolonies in that only certain individuals of the colony take part in the\nprocess of reproduction and these individuals are of two distinct types;\none is a larger, food-laden cell or egg and the other a small, active,\nfertilizing cell. The motile forms are produced in much greater numbers\nthan the eggs, plainly because they have to seek the egg and many will\ndoubtless perish before this can be accomplished. This disparity in number\nis only a means of insuring fertilization of the egg. The remaining cells\nof the body carry on the ordinary activities of the colony such as\nlocomotion and nutrition and have ceased to take any part in the\nproduction of new colonies.\n\n=Natural Death Appears With the Establishment of a Body Distinct from the\nGerm.--=Volvox is an organism of unusual interest because in it we see a\nprophecy of what is to come. Although still regarded as a colony of\nsingle-celled individuals, it represents in reality a transition between\nthe whole group of unicellular animals termed protozoa and the many celled\nanimals characterized by the possession of distinct tissues, known as\n_Metazoa_. Moreover, it shows an interesting stage in the establishment of\na body or _soma_ distinct from special reproductive cells which have taken\non the function of reproducing the colony. In such colonial forms natural\ndeath is found appearing for the first time, the reproductive cells alone\ncontinuing to perpetuate the species. Then again Volvox represents an\nimportant step in the establishment of sex in the animal kingdom for in\nits sexual reproduction the conjugating cells known as _gametes_ are no\nlonger alike in appearance but have become differentiated into definite\nova and spermatozoa.\n\nIn Volvox as in the other organisms which we have studied we find that all\nof the cells including the germ-cells are produced by the repeated\ndivision of a parent cell, and consequently each must contain the\ncharacteristic living substance of that parent. Many other forms might be\ncited to illustrate reproduction in single-celled animals, whether free or\nin colonies, but all such cases would be practically but repetitions or\nmodifications of those we have already examined.\n\n=Specialization in Higher Organisms.--=If we pass on to the higher animals\nand plants which are not single cells or colonies of similar cells but\norganisms made up of many different kinds of cells, we find a pronounced\nextension of the phenomenon met with in Volvox. Instead of each cell\nexecuting independently all of the life relations, certain ones are set\napart for the performance of certain functions to the exclusion of other\nfunctions which are carried on by other members of the aggregation. Thus\nthe organism as a whole has all the life relations carried on, but, as it\nwere, by specialists.\n\n=Sexual Phenomena in Higher Forms.--=In the reproduction of multicellular\norganisms, one sees likewise but a continuation of the phenomena exhibited\nin Volvox. Ordinarily, each new form is produced by the successive\ndivisions of a single germ-cell which in the vast majority of cases has\nconjugated with another germ-cell. In the development of the egg, as the\ndivisions proceed, groups of cells become modified for their particular\nwork until the entire organism is completed. During development certain\ncells are set apart for reproduction of the form just as they were in\nVolvox. These two kinds of reproductive cells in multicellular organisms\nare derived ordinarily from two separate individuals known as male and\nfemale, though there are some exceptions. The main difference between\nthese cells which will have to unite to form a single fertile germ-cell,\nis that they have specialized in different directions; one is small and\nactive, the other large, food-laden and passive. But with two such\ngerm-cells coming as they do from two individuals, one the male, the other\nthe female, it is obvious that the actual living substance of which each\ngerm is composed will be distinctive of its own parental line and that\nwhen the germs unite these distinctive factors commingle, hence the\ncomplications of double ancestry arise.\n\n=Structure of the Cell.--=Before we can understand certain necessary\ndetails of the physical mechanism of inheritance we must inquire a little\nfurther into the finer structure of the cell and into the nature of cell\ndivision. A typical cell, as it would appear after treatment with various\nstains which bring out the different parts more distinctly, is shown in\nFig. 3, p. 21. Typical, not that any particular kind of living cell\nresembles it very closely in appearance, but because it shows in a\ndiagrammatic way the essential parts of a cell. In the diagram, there are\ntwo well-marked regions; a central _nucleus_ and a peripheral cell-body or\n_cytoplasm_. Other structures are pictured but only a few of them need\ncommand our attention at present. At one side of the nucleus one observes\na small dot or granule surrounded by a denser area of cytoplasm. This body\nis called the _centrosome_. The nucleus in this instance is bounded by a\nwell-marked nuclear membrane and within it are several substances. What\nappear to be threads of a faintly staining material, the _linin_, traverse\nit in every direction and form an apparent network. The parts on which we\nwish particularly to rivet our attention are the densely stained\nsubstances scattered along or embedded in the strands of this network in\nirregular granules and patches. This substance is called _chromatin_. It\ntakes its name from the fact that it shows great affinity for certain\nstains and becomes intensely colored by them. This deeply colored portion\nof the cell, the chromatin, is by most biologists regarded as of great\nimportance from the standpoint of heredity. One or more larger masses of\nchromatin or chromatin-like material, known as _chromatin nucleoli_, are\noften present, and not infrequently a small spheroidal body, differing in\nits staining reactions from the chromatin-nucleolus and sometimes called\nthe _true nucleolus_, exists.\n\n=Cell-Division.--=In the simplest type of cell-division the nucleus first\nconstricts in the middle, and finally the two halves separate. This\nseparation is followed by a similar constriction and final division of the\nentire cell-body, which results in the production of two new cells. This\nform of cell-division is known as _simple_ or _direct division_. Such a\nsimple division, while found in higher animals, is less frequent and\napparently much less significant than another type of division which\ninvolves profound changes and rearrangements of the nuclear contents. The\nlatter is termed _mitotic_ or _indirect_ cell-division. Fig. 6, p. 33,\nillustrates some of the stages which are passed through in indirect\ncell-division. The centrosome which lies passively at the side of the\nnucleus in the typical cell (Fig. 6_a_, p. 33) awakens to activity,\ndivides and the two components come to lie at the ends of a fibrous\nspindle. In the meantime, the interior of the nucleus is undergoing a\ntransformation. The granules and patches of chromatin begin to flow\ntogether along the nuclear network and become more and more crowded until\nthey take on the appearance of one or more long deeply-stained threads\nwound back and forth in a loose skein in the nucleus (Fig. 6_b_, p. 33).\nIf we examine this thread closely, in some forms it may be seen to consist\nof a series of deeply-stained chromatin granules packed closely together\nintermingled with the substance of the original nuclear network.\n\nAs the preparations for division go on the coil in the nucleus breaks up\ninto a number of segments which are designated as _chromosomes_ (Fig.\n6_c_, p. 33). The nuclear membrane disappears. The chromosomes and the\nspindle-fibers ultimately become related in such a way that the\nchromosomes come to lie at the equator of the spindle as shown in Fig\n6_d_, p. 33. Each chromosome splits lengthwise to form two daughter\nchromosomes which then diverge to pass to the poles of the spindle (Figs.\n6_e_ and _f_, p. 33). Thus each end of the spindle comes ultimately to be\noccupied by a set of chromosomes. Moreover each set is a duplicate of the\nother, because the substance of any individual chromosome in one group has\nits counterpart in the other. In fact this whole complicated system of\nindirect division is regarded by most biologists as a mechanism for\nbringing about the precise halving of the chromosomes.\n\n\n[Illustration: FIG. 6\n\nDiagram showing representative stages in mitotic or indirect\ncell-division: _a_, resting cell with reticular nucleus and single\ncentrosome; _b_, the two new centrosomes formed by division of the old one\nare separating and the nucleus is in the spireme stage; _c_, the nuclear\nwall has disappeared, the spireme has broken up into six separate\nchromosomes, and the spindle is forming between the two centrosomes; _d_,\nequatorial plate stage in which the chromosomes occupy the equator of the\nspindle; _e_, _f_, each chromosome splits lengthwise and the daughter\nchromosomes thus formed approach their respective poles; _g_,\nreconstruction of the new nuclei and division of the cell body; _h_,\ncell-division completed.]\n\n\nThe chromosomes of each group at the poles finally fuse and two new\nnuclei, each similar to the original one, are constructed (Figs. 6_g_ and\n_h_, p. 33). In the meantime a division of the cell-body is in progress\nwhich, when completed, results in the formation of two complete new cells.\n\nAs all living matter if given suitable food, can convert it into living\nmatter of its own kind, there is no difficulty in conceiving how the new\ncell or the chromatin material finally attains to the same bulk that was\ncharacteristic of the parent cell. In the case of the chromatin, indeed,\nit seems that there is at times a precocious doubling of the ordinary\namount of material before the actual division occurs.\n\n=Chromosomes Constant in Number and Appearance.--=With some minor\nexceptions, to be noted later, which increase rather than detract from the\nsignificance of the facts, the chromosomes are always the same in number\nand appearance in all individuals of a given species of plants or animals.\nThat is, every species has a fixed number which regularly recurs in all of\nits cell-divisions. Thus the ordinary cells of the rat, when preparing to\ndivide, each display sixteen chromosomes, the frog or the mouse,\ntwenty-four, the lily twenty-four, and the maw-worm of the horse only\nfour. The chromosomes of different kinds of animals or plants may differ\nvery much in appearance. In some they are spherical, in others rod-like,\nfilamentous or perhaps of other forms. In some organisms the chromosomes\nof the same nucleus may differ from one another in size, shape and\nproportions, but if such differences appear at one division they appear at\nothers, thus showing that in such cases the differences are constant from\none generation to the next.\n\n=Significance of the Chromosomes.--=The question naturally arises as to\nwhat is the significance of the chromosomes. Why is the accurate\nadjustment which we have noted for their division necessary? The very\nexistence of an elaborate mechanism so admirably adapted to their precise\nhalving, predisposes one toward the belief that the chromosomes have an\nimportant function which necessitates the retention of their individuality\nand their equal division. Many biologists accept this along with other\nevidence as indicating that in chromatin we have a substance which is not\nthe same throughout, that different regions of the same chromosome have\ndifferent physiological values.\n\nWhen the cell prepares for divisions, the granules, as we have seen,\narrange themselves serially into a definite number of strands which we\nhave termed chromosomes. Judging from all available evidence, the granules\nare self-propagating units; that is, they can grow and reproduce\nthemselves. So that what really happens in mitosis in the splitting of the\nchromosomes is a precise halving of the series of individual granules of\nwhich each chromosome is constituted, or in other words each granule has\nreproduced itself. Thus each of the two daughter cells presumably gets a\nsample of every kind of chromosomal particle, hence, the two cells are\nqualitatively alike. To use a homely illustration we may picture the\nindividual chromosomes to ourselves as so many separate trains of freight\ncars, each car of which is loaded with different merchandise. Now, if\nevery one of the trains could split along its entire length and the\nresulting halves each grow into a train similar to the original, so that\ninstead of one there would exist two identical trains, we should have a\nphenomenon analogous to that of a dividing chromosome.\n\n=Cleavage of the Egg.--=It is through a series of such divisions as these\nthat the zygote or fertilized egg-cell builds up the tissues and organs of\nthe new organism. The process is technically spoken of as _cleavage_.\nCleavage generally begins very shortly after fertilization. The fertile\negg-cell divides into two, the resulting cells divide again and thus the\nprocess continues, with an ever-increasing number of cells.\n\n=Chief Processes Operative in Building the Body.--=Although of much\ninterest, space will not permit of a discussion in detail of the building\nup of the special organs and tissues of the body. It must suffice merely\nto mention the four chief processes which are operative. These are, (1)\ninfoldings and outfoldings of the various cell complexes; (2)\nmultiplication of the component cells; (3) special changes (_histological\ndifferentiation_) in groups of cells; and (4) occasionally resorption of\ncertain areas of parts.\n\n=The Origin of the New Germ-Cells.--=On account of the unusual importance\nfrom the standpoint of inheritance, which attaches to the germ-cells, a\nfinal word must be said about their origin in the embryo. While the\nevidence is conflicting in some cases, in others it has been well\nestablished that the germ-cells are set apart very early from the cells\nwhich are to differentiate into the ordinary body tissues. Fig. 7_A_, p.\n38, shows a section through the eight-celled stage of _Miastor_, a fly, in\nwhich a single large, primordial germ-cell (_p. g. c._) has already been\nset apart at one end of the developing embryo. The nuclei of the rest of\nthe embryo still lie in a continuous protoplasmic mass which has not yet\ndivided up into separate cells. The densely stained nuclei at the opposite\nend of the section are the remnants of nurse-cells which originally\nnourished the egg. Fig. 7_B_, p. 38, is a longitudinal section through a\nlater stage in the development of _Miastor_; the primitive germ-cells\n(ooeg) are plainly visible. Still other striking examples might be cited.\nEven in vertebrates the germ-cells may often be detected at a very early\nperiod.\n\n=Significance of the Early Setting Apart of the Germ-Cells.--=It is of\ngreat importance for the reader to grasp the significance of this early\nsetting apart of the germ-cells because so much in our future discussion\nhinges on this fact. The truth of the statement made in a previous chapter\nthat the body of an individual and the reproductive substance in that body\nare not identical now becomes obvious. For in such cases as those just\ncited one sees the germinal substance which is to carry on the race set\naside at an early period in a given individual; it takes no part in the\nformation of that individual's body, but remains a slumbering mass of\npotentialities which must bide its time to awaken into expression in a\nsubsequent generation. Thus an egg does not develop into a body which in\nturn makes new germ-cells, but body and germ-cells are established at the\nsame time, the body harboring and nourishing the germ-cells, but not\ngenerating them (Fig. 2, p. 13). The same must be true also in many cases\nwhere the earliest history of the germ-cells can not be visibly followed,\nbecause in any event, in all higher animals, they appear long before the\nembryo is mature and must therefore be descendants of the original\negg-cell and not of the functioning tissues of the mature individual. This\nneed not necessarily mean that the germ-cells have remained wholly\nunmodified or that they continue uninfluenced by the conditions which\nprevail in the body, especially in the nutritive blood and lymph stream,\nalthough as a matter of fact most biologists are extremely skeptical as to\nthe probability that influences from the body beyond such general\nindefinite effects as might result from under-nutrition or from poisons\ncarried in the blood, modify the intrinsic nature of the germinal\nsubstances to any measurable extent.\n\n\n[Illustration: FIG. 7\n\nA--Germ-cell (_p. g. c._) set apart in the eight-celled stage of cleavage\nin _Miastor americana_ (after Hegner). The walls of the remaining seven\nsomatic cells have not yet formed though the resting or the dividing (_M\np_) nuclei may be seen; _c R_, chromatin fragments cast off from the\nsomatic cells.\n\nB--Section lengthwise of a later embryo of _Miastor_; the primordial\negg-cells (_ooeg__{3}) are conspicuous (after Hegner).]\n\n\n=Germinal Continuity.--=The germ-cells are collectively termed the\n_germinal protoplasm_ and it is obvious that as long as any race continues\nto exist, although successive individuals die, some germinal protoplasm is\nhanded on from generation to generation without interruption. This is\nknown as the theory of _germinal continuity_. When the organism is ready\nto reproduce its kind the germ-cells awaken to activity, usually\nundergoing a period of multiplication to form more germ-cells before\nfinally passing through a process of what is known at _maturation_, which\nmakes them ready for fertilization. The maturation process proper, which\nconsists typically of two rapidly succeeding divisions, is preceded by a\nmarked growth in size of the individual cells.\n\n=Individuality of Chromosomes.--=Before we can understand fully the\nsignificance of the changes which go on during maturation we shall have to\nknow more about the conditions which prevail among the chromosomes of\ncells. As already noted each kind of animal or plant has its own\ncharacteristic number and types of chromosomes when these appear for\ndivision by mitosis. In many organisms the chromosomes are so nearly of\none size as to make it difficult or impossible to be sure of the identity\nof each individual chromosome, but on the other hand, there are some\norganisms known in which the chromosomes of a single nucleus are not of\nthe same size and form (Fig. 8, p. 41). These latter cases enable us to\ndetermine some very significant facts. Where such differences of shape and\nproportion occur they are constant in each succeeding division so that\nsimilar chromosomes may be identified each time. Moreover, in all ordinary\nmitotic divisions where the conditions are accurately known, these\nchromosomes of different types are found to be present as pairs of similar\nelements; that is, there are two of each form or size.\n\n=Pairs of Similar Chromosomes in the Nucleus Because One Chromosome Comes\nfrom Each Parent.--=When we recall that the original fertilized egg from\nwhich the individual develops is really formed by the union of two\ngametes, ovum and spermatozoon, and that each gamete, being a true cell,\nmust carry its own set of chromosomes, the significance of the pairs of\nsimilar chromosomes becomes evident; one of each kind has probably been\ncontributed by each gamete. This means that the zygote or fertile ovum\ncontains double the number of chromosomes possessed by either gamete, and\nthat, moreover, each tissue-cell of the new individual will contain this\ndual number. For, as we have seen, the number of chromosomes is, with\npossibly a few exceptions, constant in the tissue-cells and early\ngerm-cells in successive generations of individuals. For this to be true\nit is obvious that in some way the nuclei of the conjugating gametes have\ncome to contain only half the usual number. Technically the tissue-cells\nare said to contain the _diploid_ number of chromosomes, the gametes the\nreduced or _haploid_ number.\n\n\n[Illustration: FIG. 8\n\nA--Chromosomes of the mosquito (_Culex_) after Stevens.\n\nB--Chromosomes of the fruit-fly (_Drosophila_) after Metz.\n\nBoth of these forms have an unusually small number of chromosomes.]\n\n\n=In Maturation the Number of Chromosomes Is Reduced by One-Half.--=This\nhalving, or as it is known, _reduction_ in the number of chromosomes is\nthe essential feature of the process of maturation. It is accomplished by\na modification in the mitotic division in which instead of each chromosome\nsplitting lengthwise, as in ordinary mitosis, the chromosomes unite in\npairs (Fig. 9_b_, p. 42), a process known technically as _synapsis_, and\nthen apparently one member of each pair passes entire into one new\ndaughter cell, the other member going to the other daughter cell (Fig.\n9_c_, p. 42). In the pairing preliminary to this _reduction division_,\nleaving out of account certain special cases to be considered later,\naccording to the best evidence at our command the union always takes place\nbetween two chromosomes which match each other in size and appearance.\nSince one of these is believed to be of maternal and the other of\npaternal origin, the ensuing division separates corresponding mates and\ninsures that each gamete gets one of each kind of chromosome although it\nappears to be a matter of mere chance whether or not a given cell gets the\npaternal or the maternal representative of that kind.\n\n\n[Illustration: FIG. 9\n\nDiagram to illustrate spermatogenesis: _a_, showing the diploid number of\nchromosomes (six is arbitrarily chosen) as they occur in divisions of\nordinary cells and spermatogonia; _b_, the pairing (synapsis) of\ncorresponding mates in the primary spermatocyte preparatory to reduction;\n_c_, each secondary spermatocyte receives three, the haploid number of\nchromosomes; _d_, division of the secondary spermatocytes to form _e_,\nspermatids, which transform into _f_, spermatozoa.]\n\n\n=Maturation of the Sperm-Cell.--=In the maturation of the male gamete the\ngerm-cell, now known as a _spermatogonium_, increases greatly in size to\nbecome a _primary spermatocyte_. In each primary spermatocyte the pairing\nof the chromosomes already alluded to occurs as indicated in Fig. 9_b_, p.\n42, where six is taken arbitrarily to indicate the ordinary or _diploid_\nnumber of chromosomes, and three the reduced or _haploid_ number. The\ndivision of the primary spermatocyte gives rise to two _secondary\nspermatocytes_ (_c_), the paired chromosomes separating in such a way that\na member of each pair goes to each secondary spermatocyte. Each secondary\nspermatocyte (_d_) soon divides again into two _spermatids_ (_e_), but in\nthis second division the chromosomes each split lengthwise as in an\nordinary division so that there is no further reduction. In some forms the\nreduction division occurs in the secondary spermatocytes instead of the\nprimary. Each spermatid transforms into a mature spermatozoon (_f_). The\nspermatozoa of most animals are of linear form, each with a head, a\nmiddle-piece and a long vibratile tail which is used for locomotion. The\nhead consists for the most part of the transformed nucleus and is\nconsequently the part which bears the chromosomes.\n\n=Maturation of the Egg-Cell.--=As regards the behavior of the chromosomes\nthe maturation of the ovum parallels that of the sperm-cell. There are not\nso many primordial germ-cells formed and only one out of four of the\nultimate cells becomes a functional egg. As in maturation of the\nsperm-cell there is a growth period in which _ooegonia_ enlarge to become\n_primary ooecytes_ (Fig. 10_b_, p. 45). In each primary ooecyte as in the\nprimary spermatocyte the chromosomes pair and two rapidly succeeding\ndivisions follow in one of which the typical numerical reduction in the\nchromosomes occurs. A peculiarity in the maturation of the ovum is that\nthere is a very unequal division of the cytoplasm in cell division so that\nthree of the resulting cells usually termed _polar bodies_ are very small\nand appear like minute buds on the side of the fourth or egg-cell proper.\n\nThe scheme of this formation of the polar bodies is indicated in Fig. 10,\np. 45. In Fig. 10_b_ the chromosomes are seen paired and ready for the\nfirst division; that is, for the formation of the first polar body. Figs.\n10_c_, _d_, p. 45, show the giving off of this body. Note that while only\na small proportion of the cytoplasm passes into this tiny cell, its\nchromatin content is as great as that of the ovum. A second polar body\n(Figs. 10_e_, _f_, p. 45) is formed by the egg, but in this case each\nchromosome splits lengthwise, as in ordinary mitosis, and there is no\nfurther numerical reduction. In the meantime, typically, a third polar\nbody is formed by division of the first. (Stages _e_, _f_, _g_.)\n\n=Parallel Between the Maturation of Sperm- and Egg-Cell.--=This rather\ncomplex procedure of the germ-cells will be rendered more intelligible\nthrough a careful study of Figs. 9 and 10, pp. 42 and 45, and Fig. 11, p.\n46, which indicates the parallel conditions in spermotogenesis and\nooegenesis.\n\n\n[Illustration: FIG. 10\n\nDiagram to illustrate ooegenesis: _a_, showing the diploid number of\nchromosomes (six is arbitrarily chosen) as they occur in ordinary cells\nand ooegonia; _b_, the pairing of corresponding mates preparatory to\nreduction; _c_, _d_, reduction division, giving off of first polar body;\n_e_, egg preparing to give off second polar body, first polar body ready\nfor division; _f_, _g_, second polar body given off, division of first\npolar body completed. The egg nucleus, now known as the female pronucleus,\nand each body contain the reduced or haploid number of chromosomes.]\n\n\nThe view now generally held regarding the polar bodies is that they are\nreally abortive eggs. They later disappear, taking no part in\nembryo-formation. It can readily be seen how such an unequal division is\nadvantageous to the large cell, for it receives all of the rich store of\nfood material that would be distributed among the four cells if all were\nof equal size. This increased amount of food is a favorable provision for\nthe forthcoming offspring whose nourishment is thus more thoroughly\ninsured.\n\n\n[Illustration: FIG. 11\n\nDiagram showing the parallel between maturation of the sperm-cell and\nmaturation of the ovum.]\n\n\nOn the other hand, all of the sperm-cells develop into complete active\nforms, which, as aforesaid, usually become very much elongated and develop\na motile organ of some kind. In such cells an accumulation of food to any\nlarge extent would hinder rather than help them, because it would\nseriously interfere with their activity.\n\n=Fertilization.--=In fertilization (Fig. 12, p. 48) the spermatozoon\npenetrates the wall of the ovum and after undergoing considerable\nalteration its nucleus fuses with the nucleus of the egg. In some forms\nonly the head (nucleus) and middle-piece enter, the tail being cut off by\na so-called fertilization membrane which forms at the surface of the egg\nand effectually blocks the entrance of other spermatozoa. Thus normally\nonly one spermatozoon unites with an egg. In some forms while several may\nenter the egg only one becomes functional. As soon as the nucleus of the\nspermatozoon, now known as the male _pronucleus_, reaches the interior of\nthe egg, it enlarges and becomes similar in appearance to the female\n_pronucleus_. It swings around in such a way (Fig. 12_b_, p. 48) that the\nmiddle piece, now transformed into a centrosome, lies between it and the\nfemale pronucleus. The two pronuclei (_c_, _d_, _e_), each containing the\nreduced number of chromosomes, approach, the centrosome divides, the\nnuclear walls disappear, the typical division spindle forms, and the\nchromosomes of paternal and maternal origin respectively come to lie side\nby side at the equator of the spindle ready for the first division or\ncleavage (_f_, _g_). It will be noted that the individual chromosomes do\nnot intermingle their substance at this time, but that each apparently\nretains its own individuality. There is considerable evidence which\nindicates that throughout life the chromosomes contributed by the male\nparent remain distinct from those of the female parent. Inasmuch as each\ngerm-cell, after maturation, contains only half the characteristic number\nof chromosomes, the original number is restored in fertilization.\n\n\n[Illustration: FIG. 12\n\nDiagram to illustrate fertilization; [male], male pronucleus; [female],\nfemale pronucleus; observe that the chromosomes of maternal and paternal\norigin respectively do not fuse.]\n\n\n=Significance of the Behavior of the Chromosomes.--=The question confronts\nus as to what is the significance of this elaborate system which keeps the\nchromosomes of constant size, shape and number; which partitions them so\naccurately in ordinary cell-divisions; and which provides for a reduction\nof their numbers by half in the germ-cell while yet securing that each\nmature gamete gets one of each kind of chromosome. Most biologists look on\nthese facts as indicating that the chromosomes are specifically concerned\nin inheritance.\n\nIn the first place it is recognized that as regards the definable\ncharacters which separate individuals of the same species, offspring may\ninherit equally from either parent. And it is a very significant fact that\nwhile the ovum and spermatozoon are very unequal in size themselves, the\nchromosomes of the two germ-cells are of the same size and number. This\nparity in chromosomal contribution points clearly to the means by which an\nequal number of character-determiners might be conveyed from each parent.\nMoreover it is mainly the nucleus of the sperm-cell in some organisms\nwhich enters the egg, hence the determiners from the male line must exist\nwholly or largely somewhere in the nucleus. And the bulk of the nucleus in\nthe spermatozoon consists of the chromosomes or their products.\n\n=A Single Set of Chromosomes Derived from One Parent Only Is Sufficient\nfor the Production of a Complete Organism.--=That a single or haploid set\nof chromosomes as seen in the gametes is sufficient contribution of\nchromatin for the production of a complete organism is proved by the fact\nthat the unfertilized eggs of various animals (many echinoderms, worms,\nmollusks, and even the frog) may be artificially stimulated to development\nwithout uniting at all with a spermatozoon. The resulting individual is\nnormal in every respect except that instead of the usual diploid number it\nhas only the single or haploid number of chromosomes. Its inheritance of\ncourse is wholly of maternal origin. The converse experiment in\nechinoderms in which a nucleus of male origin (that is, a spermatozoon)\nhas been introduced into an egg from which the original nucleus has been\nremoved shows that the single set of chromosomes carried by the male\ngamete is also sufficient to cooperate with the egg-cytoplasm in\ndeveloping a complete individual.\n\n=The Duality of the Body and the Singleness of the Germ.--=Since every\nmaternal chromosome in the ordinary cell has an equivalent mate derived\nfrom the male parent, it follows therefore, supposing the chromosomes do\nhave the significance in inheritance attributed to them, that as regards\nthe measurable inheritable differences between two individuals, the\nordinary organism produced through the union of the two germ-cells is,\npotentially at least, dual in nature. On the other hand through the\nprocess of reduction the gametes are provided with only a single set of\nsuch representatives. This duality of the body and singleness of the\nmature germ is one of the most striking facts that come to light in\nembryology. How well the facts fit in with the behavior of certain\nhereditary characters will be seen later in our discussions of Mendelism.\n\n=The Cytoplasm Not Negligible in Inheritance.--=Just what part is played\nby the cytoplasm in inheritance is not clear, but it is probably by no\nmeans a negligible one. The cytoplasm of a given organism is just as\ndistinctive of the species or of the individual of which it forms a part\nas are the chromosomes. It is well established that neither nucleus nor\ncytoplasm can fully function or even exist long without the other, and\nneither can alone produce the other. They undoubtedly must cooperate in\nbuilding up the new individual, and the cytoplasm of the new individual is\npredominantly of maternal origin. It is obvious that all of the more\nfundamental characters which make up an organism, such, for instance, as\nmake it an animal of a certain order or family, as a human being or a dog\nor a horse, are common to both parents, and there is no way of measuring\nhow much of this fundamental constitution comes from either parent, since\nonly closely related forms will interbreed. In some forms, moreover, the\nbroader fundamental features of embryogeny are already established before\nthe entrance of the spermatozoon. It is probable therefore that instead of\nasserting that the entire quota of characters which go to make up a\ncomplete individual are inherited from each parent equally, we are\njustified only in maintaining that this equality is restricted to those\nmeasurable differences which veneer or top off, as it were, the\nindividual. We may infer that in the development of the new being the\nchromosomes of the egg together with those derived from the male work\njointly on or with the other germinal contents which are mostly\ncytoplasmic materials of maternal origin.\n\n=The Chromosomes Possibly Responsible for the Distinctiveness of Given\nCharacters.--=It seems probable that in the establishment of certain basic\nfeatures of the organism the cooperation of the cytoplasm with chromatin\nof either maternal or paternal origin might accomplish the same end, but\nthat certain distinctive touches are added or come cumulatively into\nexpression through influences carried, predominantly at least, in the\nchromatin from one as against the other parent. These last distinctive\ncharacters of the plant or animal constitute the individual differences of\nsuch organisms. In this connection it is a significant fact that in young\nhybrids between two distinct species the early stages of development,\nespecially as regards symmetry and regional specifications, are\nexclusively or predominantly maternal in character, but the male influence\nbecomes more and more apparent as development progresses until the final\ndegree of intermediacy is attained.\n\nFrom the evidence at hand this much seems sure, that the paternal and\nmaternal chromosomes respectively carry substances, be they ferments,\nnutritive materials or what not, that are instrumental in giving the final\nparity of personal characters which we observe to be equally heritable\nfrom either line of ancestry. It is clear that most of the characters of\nan adult organism can not be merely the outcome of any unitary substance\nof the germ. Each is the product of many cooperating factors and for the\nfinal outcome any one cooperant is probably just as important in its way\nas any other. The individual characters which we juggle to and fro in our\nbreeding experiments seem apexed, as it were, on more fundamental features\nof organic chemical constitution, polarity, regional differentiation, and\nphysiological balance, but since such individual characters parallel so\nclosely the visible segregations and associations which go on among the\nchromosomes of the germ-cells it would seem that they, at least, are\nrepresented in the chromosomes by distinctive cooperants which give the\nfinal touch of specificity to those hereditary characters which can be\nshifted about as units of inheritance.\n\n=Sex and Heredity.--=Whatever the origin of fertilization may have been in\nthe world of life, or whatever its earliest significance, the important\nfact remains that to-day it is unquestionably of very great significance\nin relation to the phenomena of heredity. For in all higher animals, at\nleast, offspring may possess some of the characteristics originally\npresent in either of two lines of ancestry, and this commingling of such\npossessions is possible only through sexual reproduction. As has already\nbeen seen, in the pairing of chromosomes previous to reduction, the\ncorresponding members of a pair always come together so that in the final\nsegregation each gamete is sure to have one of each kind although whether\na given chromosome of the haploid set is of maternal or paternal origin\nseems to be merely a matter of chance. Thus, for instance, if we\narbitrarily represent the chromosomes of a given individual by _ABC_\n_abc_, and regard _A_, _B_ and _C_ as of paternal and _a_, _b_ and _c_ as\nof maternal origin, then in synapsis only _A_ and _a_ can pair together,\n_B_ and _b_ and _C_ and _c_, but each pair operates independently of the\nother so that in the ensuing reduction division either member of a pair\nmay get into a cell with either member of the other pairs. That is, the\nline up for division at a given reduction might be any one of the\nfollowing, ABC/abc ABc/abC Abc/aBC AbC/aBc. This would yield the following\neight kinds of gametes, _ABC_, _abc_, _ABc_, _abC_, _Abc_, _aBC_, _AbC_,\n_aBc_, each bearing one of each kind of chromosome required to cover the\nentire field of characters necessary to a complete organism. And since\neach sex would be equally likely to have these eight types of gametes and\nany one of the eight in one individual might meet any one of the eight of\nthe other, the possible number of combinations in the production of a new\nindividual from such germ-cells would be 8x8, or 64. With the larger\nnumbers of chromosomes which exist in most animals it is readily seen that\nthe number of possible combinations becomes very great. Thus any\nindividual of a species with twenty chromosomes--and many animals,\nincluding man, have more--would have ten pairs at the reduction period and\ncould therefore form (2)^{10}, or 1,024 different gametes in each sex. And\nsince any one of these in one sex would have an equal chance of meeting\nwith any one in the opposite sex, the total number of possible different\nzygotes that might be produced would be (1,024)^{2}, or 1,048,576. Sex\ntherefore, through recombinations of ancestral materials, undoubtedly\nmeans, among other things, the production of great diversity in\noffspring.\n\n\nDETERMINATION OF SEX\n\n=Many Theories.--=From earliest times the problem of sex determination has\nbeen one of keen interest, and needless to say hundreds of theories have\nbeen propounded to explain it. Geddes and Thomson say that Drelincourt\nrecorded two hundred sixty-two so-called theories of sex production and\nremark that since his time the number has at least been doubled. The\ndesirability of controlling sex has naturally appealed strongly to\nbreeders of domesticated animals.\n\nA study of animals born in litters, or of twins, is enough in itself to\nmake us skeptical of theories of sex-determination based on nutritional or\nexternal factors. In a litter of puppies, for example, there are usually\nboth males and females, although in their prenatal existence they have all\nbeen subject to the same nutritional and environmental conditions.\nLikewise in ordinary human twins one may be a boy, the other a girl,\nwhereas if the nutritional condition of the mother were the fact\ndetermining sex, both should be boys or both girls. However, there are\ntwins known as _identical twins_ who are remarkably alike and who are\nalways of the same sex. But there is reason to suppose that identical\ntwins in reality come from the same zygote. Presumably in early\nembryogeny, probably at the two-celled stage of cleavage, the two\nblastomeres become separated and each gives rise to a complete individual\ninstead of only the half of one it would have produced had the two\nblastomeres remained together. Such twins are monochorial; that is, they\ngrow inside the same fetal membrane, whereas each ordinary twin has its\nown fetal membrane and has obviously originated from a separate ovum. It\nhas been established experimentally in several kinds of animals that early\ncleavage blastomeres when isolated can each develop into a complete\nindividual. In man, ordinary twins are no more alike than ordinary\nbrothers and sisters, but identical twins are strikingly similar in\nstructure, appearance, habits, tastes, and even susceptibility to various\nmaladies. The fact that they are invariably of the same sex is a strong\nreason for believing that sex was already developed in the fertile ovum\nand consequently in the resulting blastomeres from that ovum.\n\nThe young of the nine-banded armadillo in a given litter are invariably of\nthe same sex and are closely similar in all features. Newman and Patterson\nhave shown that all the members of a litter come from the same egg.\nPatterson has established the fact that cleavage of the egg takes place in\nthe usual manner, but later separate centers of development appear in the\nearly embryonic mass and give rise to the separate young individuals.\n\nAgain in certain insects where one egg indirectly gives rise to a chain of\nembryos, or to a number of separate larvae, possibly as many as a thousand,\nall of the latter are of the same sex. Even in some plants researches have\nshown that sex is already determined at the beginning of development.\nThen, too, much evidence has come to light recently showing that\nsex-characters in certain cases behave as heritable characters and are\nindependent of external conditions. Lastly there is visible and convincing\nevidence obtainable through microscopical observations that sex is\ndetermined by a mechanism in the germ-cells themselves. It is chiefly to\nthese latter facts that I wish to direct attention for the present.\n\n=The Sex Chromosome.--=The evidence centers about a special chromosome or\nchromosome-group commonly designated as the _sex-chromosome_ or\n_X-element_, which has been found in various species of animals, including\nman. In the males of such animals this chromosome is present in addition\nto the regular number of pairs, thus giving rise to an _uneven_ instead of\nthe conventional even number of chromosomes. This element remains\nundivided in one of the maturation divisions of the spermatocytes, in some\nforms in the first in others in the second, and passes entire to one pole\nof the spindle (Fig. 13, p. 58). This results in the production of two\nclasses of cells, one containing the _X_-element and one not. The outcome\nis that two corresponding classes of spermatozoa are produced. The\nphenomena involved are diagrammatically represented in Fig. 13. It has\nbeen clearly demonstrated in several cases that eggs fertilized by\nspermatozoa which possess this _X_-element, always become females, those\nfertilized by spermatozoa which do not possess it always develop into\nmales.\n\n\n[Illustration: FIG. 13\n\nDiagram illustrating the behavior of the _x_-element or sex-chromosome in\nthe maturation of the sperm-cell. In one of the two maturation divisions\n(represented here as in the first) it passes undivided to one pole (_a_,\n_b_, _c_), in the other it divides. Since the cell without the _x_-element\nalso divides the result is that ultimately from the original primary\nspermatocyte (_a_) four cells are formed (_f_), two with the _x_-element\nand two without it. Half of the spermatozoa therefore will bear an\n_x_-element, half will be without it. In _a_ the ordinary chromosomes,\narbitrarily indicated as 10, are supposed to have already paired for\nreduction so that the original diploid number in spermatogonia and\nbody-cells of the male would be 20 plus the _x_-chromosome.]\n\n\nIt has been found, furthermore, that in species in which the males possess\nthis extra element the females have two of them. That is, if the original\nnumber in the somatic cells of the male were twenty-three, twenty-two\nordinary and one _X_-element, the number in the somatic cells of the\nfemale would be twenty-four, or twenty-two ordinary and two _X_-elements.\nIt has been found that when the chromosomes of the female pair for the\nreduction division, each chromosome uniting with its corresponding fellow,\nthe two _X_-elements in the female pair in the usual way so that every\negg-cell possesses an _X_-element. Thus every mature egg has an\n_X_-element, while only half of the spermatozoa have one. That is, if we\nassume twenty-three as the diploid number present originally in the\nsomatic cells of the male and twenty-four as the number in the female,\nthen one-half the spermatozoa of the male would contain the haploid number\neleven, and the other half, the number twelve, whereas every mature ovum\nwould contain twelve. Since there are equal numbers of the spermatozoa\nwith the _X_-element and without it, and inasmuch as presumably under\nordinary conditions one kind is as likely to fertilize the egg as the\nother, then there are equal chances at fertilization of producing a zygote\nwith two _X_-elements or with but one.\n\n  Thus, Spermatozoon + _X_ by Ovum + _X_ = Zygote + _XX_.\n        Spermatozoon (no _X_) by Ovum + _X_ = Zygote + _X_.\n\nWe have already seen that the former is always female, the latter male. It\nthus becomes possible to distinguish the sex of an embryo by counting the\nchromosomes of its cells. This has been accomplished in several cases.\n\nIn some instances[1] the conditions may be much more complex than the\nones indicated--too complex in fact to warrant detailed discussion in an\nelementary exposition--but the principle remains the same throughout, the\nvery complexity when thoroughly understood, strengthening rather than\nweakening the evidence. In a few forms an interesting reversal of\nconditions has been found in that the eggs instead of the spermatozoa show\nthe characteristic dimorphism.\n\nJust what the exact relationship between sex-differentiation and the\n_X_-element is has never been clearly established. It is possible that\nthis element is an actual sex-determinant, in the ordinary cases one\n_X_-element determining the male condition and two _X_-elements producing\nthe female condition. On the other hand it might be argued that it is not\nthe determining factor but the expression of other cell activities which\ndo determine sex; that is, a sex accompaniment. Or again, it may be one of\nseveral essential factors which must cooperate to determine sex.\n\n\nSEX-LINKED CHARACTERS\n\nThe discovery of the remarkable behavior of certain characters in heredity\nwhich can only be plausibly explained by supposing that they are linked\nwith a sex-determining factor still further strengthens our belief in the\nexistence of such a definite factor. Such characters are commonly termed\nsex-linked characters.\n\n=Sex-Linked Characters in Man.--=Since there are a number of them in man\nwe may choose one of these, such as color-blindness, for illustration. The\ncommon form of color-blindness known as Daltonism in which the subject\ncan not distinguish reds from greens, a condition which seems to be due to\nthe absence of something which is present in individuals of normal color\nvision, is far commoner in men than in women. Its type of inheritance,\nsometimes termed \"crisscross\" heredity, has been likened to the knight\nmoves in a game of chess. The condition is transmitted from a color-blind\nman through his daughter to half of her sons. Or, to go more into detail,\na color-blind father and normal mother have only normal children whether\nsons or daughters. The sons continue to have normal children but the\ndaughters, although of normal vision themselves, transmit color-blindness\nto one-half of their own sons. If such a woman marries a color-blind man,\nas might easily happen in a marriage between cousins, then as a rule\none-half her daughters as well as one-half her sons will be color-blind.\n\n\n[Illustration: FIG. 14\n\nDiagram illustrating the inheritance of a sex-limited character such as\ncolor-blindness in man on the assumption that the factor in question is\nlocated in the sex-chromosome (from Loeb after Wilson). The normal\nsex-chromosome is indicated by a black =X=, the one lacking the factor for\ncolor perception, by a light X. It is assumed that a normal female is\nmated with a color-blind male.]\n\n\nIn such cases what appears to be a mysterious procedure becomes very\nsimple if we assume that the defective character is associated with the\nsex-determining factor, or to make it concrete let us say with the\n_X_-element. The chart shown in Fig. 14, p. 62, indicates what the\ngerminal condition would be under the circumstances. The column to the\nright represents the maternal, the one to the left the paternal line.\nSince two _X_ means female and one _X_ male, and inasmuch as we have\nassumed that the physical basis of the defect to which color-blindness is\ndue is conveyed by the _X_-element, we may represent the defective single\n_X_ of the male in outline only (see first row). It is obvious that after\nthe reduction divisions (second row) the mature sex-cells of the female\nwill each contain a single normal _X_, the corresponding sex cells of the\nmale will contain either no _X_ or a defective _X_. Since if any member of\nthe class of spermatozoa containing no _X_, fertilizes an egg the\nresulting zygote (row three) will have but one _X_ and that a normal one,\nthe individual which develops from the zygote will be normal as regards\ncolor vision and moreover will be male because the condition one _X_\nalways means maleness. On the other hand, if any member of the class of\nspermatozoa containing the defective _X_ fertilizes an egg two\n_X_-elements are brought together and this of itself means femaleness. In\nthis case one of the _X_-elements is defective but the single normal _X_\nis sufficient in itself to produce normal color vision. But when it comes\nto the maturation of the sex-cells of this female, the pair of\n_X_-elements are separated in the usual way with the result that half of\nthe mature ova contain a normal _X_ and half a defective _X_ (row four).\nSince in a normal male, however, the mature reproductive cells will\ncontain either a normal _X_ or no _X_ (fourth row), any one of four\ndifferent kinds of matings may result. A sex-cell carrying normal _X_ of\nthe male may combine with an ovum containing normal X producing a normal\nfemale (row five). Or such a cell may combine with an ovum carrying the\ndefective _X_, also producing a female but one who although of normal\ncolor vision herself, like her mother, is a carrier of the defect. On the\nother hand, any one of the spermatozoa without an _X_ may combine with an\novum containing the normal _X_, in which case a normal male is produced\nand, moreover, one who, like his mother's brothers, is incapable of\ntransmitting the defect. However, the sperm-cell devoid of an _X_ is just\nas likely to fertilize an ovum carrying the defective _X_, in which event\nthe resulting individual, a male, must be color-blind because he contains\nthe defective _X_ alone. In other words, the chances are that one-half the\nsons of a woman whose father was color-blind will be color-blind, the\nother half perfectly normal; and that all of the daughters will be of\nnormal color vision although one-half of them will probably transmit the\ndefect to one-half of their sons. From a glance at the diagram it is\nreadily seen also that a color-blind female could result from the union of\na color-blind man (see first row) and the daughter of a color-blind man\n(see third row). For half of the gametes of such a female would bear the\ndefect as would also that half of the gametes of the male which carry _X_,\nhence the expectation would be that half of the daughters of such a union\nwould be color-blind and half would be carriers of color-blindness; and\nthat half of the sons would be color-blind and half normal. All the sons\nof a color-blind woman would be color-blind because she has only defective\n_X_-elements to pass on.\n\nThe inheritance of various other conditions in man follows more or less\naccurately the same course as color-blindness. Among these may be\nmentioned: _hemophilia_, a serious condition in which the blood will not\nclot properly, thus rendering the affected individual constantly liable to\nsevere or fatal hemorrhage; near-sightedness (_myopia_) in some cases; a\ndegenerative disease of the spinal cord known as _multiple sclerosis_;\nprogressive atrophy of the optic nerve (_neuritis optica_); Gower's\n_muscular atrophy_; some forms of _night-blindness_; in some cases\n_ichthyosis_, a peculiar scaly condition of the skin. In one of my own\ntabulations of a case of inheritance of \"webbed\" digits or _syndactyly_, a\ncondition in which two or more fingers or toes are more or less united, a\nsex-linked inheritance is clearly indicated (Fig. 15), although from the\npedigrees recorded by other investigators this condition usually appears\nin some of both the sons and daughters of an affected individual.\n\n\n[Illustration: FIG. 15\n\nChart showing the inheritance of a case of syndactyly after the manner of\na sex-linked character. The affected individuals are represented in black;\nsquares indicate males, circles females. The condition is seen to be\ninherited by males through unaffected females.]\n\n\n=The Occurrence of Sex-Linkage in Lower Forms Renders Experiments\nPossible.--=The course followed by such characters in man can be inferred\nonly from the pedigrees we can obtain from family histories. Fortunately,\nhowever, such sex-linkage also occurs in lower animals and we are able\ntherefore to verify and extend our observations by direct experiments in\nbreeding. Several sex-linked characters have been found to exist in a\nsmall fruit-fly known as _Drosophila_. Extensive breeding experiments with\nthis fly by Professor T. H. Morgan and his pupils have borne out\nremarkably the interpretation that the characters in question are really\nlinked with a sex-determining factor.\n\n\n\n\nCHAPTER III\n\nMENDELISM\n\n\n=New Discoveries in the Field of Heredity.--=Writing in 1899, one of\nAmerica's well-known zoologists asserts that, \"It is easier to weigh an\ninvisible planet than to measure the force of heredity in a single grain\nof corn.\" And yet only two or three years later we find another prominent\nnaturalist saying regarding heredity that, \"The experiments which led to\nthis advance in knowledge are worthy to rank with those that laid the\nfoundation of the atomic laws of chemistry.\" Again, \"The breeding pen is\nto us what the test-tube is to the chemist--an instrument whereby we\nexamine the nature of our organisms and determine empirically their\ngenetic properties.\" Here is a decided contrast of statement and yet both\nwere justifiable at the time of utterance. For even at the writing of the\nfirst statement the investigations were in progress which, together with\nthe rediscovery of certain older work, were to transfer our knowledge of\nheredity from the realm of speculation to that of experiment and disclose\ncertain definite principles of genetic transmission.\n\nThrough a knowledge of these principles in fact, the shifting of certain\ncharacters is reducible to a series of definitely predictable proportions\nand the skilled breeder may proceed to the building up of new and\npermanent combinations of desirable characters according to mathematical\nratios and, what is of equal importance, he can secure the elimination of\nundesirable qualities. While there are many limitations in the application\nof these principles and while new facts and modifications are constantly\nbeing discovered concerning them, nevertheless they represent the first\napproximations to definite laws of hereditary transmission that we have\never been able to make, and the practical fact confronts us that whatever\nour theoretical interpretations may be, the principles are so definite\nthat through their application important improvements of crops and\ndomesticated animals have already actually been secured and one may\nconfidently expect still others to follow.\n\n=Mendel.--=The principles involved are called the Mendelian principles\nafter their discoverer, Gregor Johann Mendel, abbot of a monastery at\nBruenn, Austria. After eight years of patient experimenting in his cloister\ngarden with plants, chiefly edible peas, he published his results and\nconclusions in 1866, in the _Proceedings of the Natural History Society of\nBruenn_. While known to a few botanists of that day, the full importance of\nthe contribution was not recognized, and in the excitement of the\npost-Darwinian controversy, the facts were lost sight of and ultimately\nforgotten.\n\n=Rediscovery of Mendelian Principles.--=In 1900 three men, Correns, De\nVries and Tschermak, working independently--in different countries, in\nfact--rediscovered the principles and called attention anew to the\nlong-forgotten work of Mendel which they had come upon in looking over the\nolder literature on plant breeding. These investigators added other\nexamples from their own experiments. Since their rediscovery the\nprinciples have been confirmed in essential features and extended by\nnumerous experimentalists with regard to a wide range of hereditary\ncharacters in both animals and plants.\n\n=Independence of Inheritable Characters.--=It has been found that many\ntruly heritable characteristics or traits of an individual, whether plant\nor animal, are comparatively independent of one another and may be\ninherited independently. Where there are contrasted characters in father\nand mother, such as white plumage and black plumage in fowls, smooth coat\nand wrinkled coat in seed, horns and hornlessness in cattle, long fur and\nshort fur in rabbits, beard and beardlessness in wheat, albino condition\nand normal condition, etc., there is obviously a bringing together of the\ndeterminers of the two traits in the resulting offspring. In the third\ngeneration, however, in the progeny of these offspring, the two distinct\ncharacters may be set apart again, thus showing that in the second\ngeneration while perhaps one only was visible, the factors which determine\nboth were nevertheless present, and moreover, they were present in a\nseparable condition.\n\n=Illustration of Mendelism in the Andalusian Fowl.--=Let us take as a\nsimple example the case of the Andalusian fowl. Although it is not a case\nestablished by Mendel it illustrates certain of the essential conditions\nunderlying Mendelism in a more obvious way than the cases worked out by\nMendel himself. The so-called blue Andalusian fowl results from a cross of\na color variety of the fowl which is black with one which is white with\nblack-splashed feathers. The result is the same irrespective of which\nparent is black. When bred with their like, whether from the same parents\nor different parents, these blue fowls produce three kinds of progeny,\napproximately one-fourth of which are black like the one grandparent,\none-fourth white like the other grandparent, and the remaining half, blue\nlike the parents (Fig. 16). Moreover, the black fowls obtained in this way\nwill, when interbred, produce only black offspring and the same is true of\nthe white fowls. To all appearances as far as color is concerned they are\nof as pure type as the original grandparents. With the blue fowls,\nhowever, the case is different, for when bred together they will produce\nthe same three kinds of progeny that their parents produced and in the\nsame proportions. Again the white and the black are true to type but the\nblue will always yield the three classes of offspring and this through\ngeneration after generation.\n\n\n[Illustration: FIG. 16\n\nDiagram showing the scheme of inheritance in the blue Andalusian fowl.]\n\n\nThese facts may be illustrated graphically as follows where the word\n\"black\" indicates the original black parent, \"white\" the original white\n(black splashed) parent and \"blue\" the hybrid offspring.\n\n  Parental\n  Generation (P)          Black x White              Black x White\n                                |                          |\n  First Filial                  |                          |\n  Generation (F_{1})          Blue          x           Blue\n                                             |\n                        +------------------------------------------+\n                        |                    |                     |\n  Second Filial       Black                 Blue                 White\n  Generation (F_{2})  (25%)                 (50%)                (25%)\n                        |                    |                     |\n                        |        +-------------------------+       |\n                        |        |           |             |       |\n  Third Filial        Black   Black         Blue          White  White\n  Generation (F_{3})    |     (25%)         (50%)         (25%)    |\n                        |        |           |             |       |\n                        |        |     +-------------+     |       |\n                        |        |     |     |       |     |       |\n  Fourth Filial       Black   Black  Black  Blue   White  White  White\n  Generation (F_{4})                 (25%)  (50%)  (25%)\n\n=The Cause of the Mendelian Ratio.--=Concerning the cause of this peculiar\nratio of inheritance in crossed forms Mendel suggested a simple\nexplanation. Animals or plants that can be cross-bred, obviously must be\nforms that produce a new individual from the union of two germ-cells, one\nof which is provided by each parent. Mendel's idea was that there must be\nsome process of segregation going on in the developing germ-cells of each\nhybrid whereby the factors for the two qualities are set apart in\ndifferent cells with the result that half of the germ-cells of a given\nindividual will contain the determiner of one character and half, the\ndeterminer of the other. That is, a given germ-cell carries a factor for\none or the other of the two alternate characters but not the factors for\nboth. In a plant, for example, in the male line, half of the pollen grains\nwould bear germ-cells carrying the determiner of one character and half,\nthat of the other. Similarly, in the female line, half of the ovules would\ncontain the determiner of the one character and half, that of the other.\nLikewise in animals as regards such pairs of characters there would be two\nclasses of germ-cells in the male and two in the female. In the case of\nthe blue Andalusian fowls under discussion this would mean that half of\nthe mature germ-cells of the male carry the black-producing factor, and\nhalf carry the white-producing factor, and the same is true of the\ngerm-cells of the female. Thus when two such crossed forms are mated,\nthere are, by the laws of chance, four possible combinations, namely: (1)\nwhite-determining sperm-cells and white-determining ovum; (2)\nwhite-determining sperm-cells and black-determining ovum; (3)\nblack-determining sperm-cells and white-determining ovum; and (4)\nblack-determining sperm-cells and black-determining ovum. Manifestly, the\nfirst combination can only give white offspring; the second, white and\nblack, gives blue (by such a cross the original blues were established);\nlikewise, the third, black and white, gives blue; and the fourth\ncombination can only give black offspring. This matter may be graphically\nrepresented by the following formulae in which B indicates the determiner\nof Black in the germ-cell and W the determiner of White: [male] signifies\nmale; [female] female.\n\n\nIN THE ORIGINAL PARENTS\n\n  W x B = WB = Blue\n\nIN THE HYBRIDS\n\n  [male] [female]\n  germ-  germ-\n  cells  cells     [male] [female]\n    W----W          W   x   W = WW = White\n      \\/            W   x   B = WB = Blue\n      /\\      or    B   x   W = BW = Blue\n    B----B          B   x   B = BB = Black\n\nThus of the four possible combinations one only can produce white fowls,\ntwo (WB or BW) can produce blue fowls, and one black fowls. That is, the\nratio is 1:2:1 or the 25, 50 and 25 per cent., respectively, of our\ndiagram. The black fowls or the white fowls will breed true in subsequent\ngenerations when mated with those of their own color because the\ndeterminer of the alternative character has been permanently eliminated\nfrom their germ-plasm; but the blue fowls will always yield three types of\noffspring because they still possess the two classes of germ-cells.\n\n=Verification of the Hypothesis.--=The hypothesis that germ-cells of\ncrossed forms are of two classes with respect to a given pair of Mendelian\ncharacters is further substantiated by the following facts. If in the case\nof the fowls under discussion one of the blue fowls is mated with an\nindividual of the white variety, half of the progeny will be blue and\nhalf white. For the hybrid has two kinds of germ-cells, black producing,\nwhich we have designated by the letter B, and white producing (or W) in\nequal number while the white parent has only one kind, white producing. It\nis obvious that if half the germ-cells of the hybrid form are of the type\nB then half the progeny will be of the BW type, which is blue, and the\nother half will be of the WW type, which is white. In the same way if we\nmate a hybrid and a black fowl, half of the progeny will be black and half\nwill be blue, that is, there could only be WB and BB types.\n\nThe fact must not be lost sight of that since the pairings are wholly\ndetermined by the laws of chance the proportions are likely to be only\napproximate. It is obvious that the greater the number of individuals, the\nnearer the results will approach the expected ratio.\n\n\nDOMINANT AND RECESSIVE\n\n=One Character May Mask the Other.--=In a large number of cases, however,\nthe actual condition of affairs is not so evident as in the Andalusian\nfowl, for instead of being intermediate or different in appearance, the\ngeneration produced by crossing resembles one parent to the exclusion of\nthe other. Such an overshadowing is spoken of as _dominance_, and the two\ncharacters are termed _dominant_ and _recessive_. Thus when brown\nring-doves and white ring-doves are mated the progeny are all brown, or if\nwild gray mice are mated to white mice the progeny are all gray. So black\nis dominant to white in rose-comb bantams; brown eyes to blue eyes in man;\nbeardlessness to beard in wheat, and likewise rough chaff to smooth, and\nthick stem to thin; tallness to dwarfness in various plants; normal\ncondition to the peculiar waltzing condition in the Japanese waltzing\nmouse. Numerous other cases might be cited but these are sufficient to\nillustrate the condition.\n\n=Segregation in the Next Generation.--=But now the question arises, what\ndo such crosses as show dominance transmit to the next generation?\nExperiments show regarding any given pair of these alternate characters\nthat they are set apart again in the succeeding generation, returning in a\ndefinite percentage to the respective grandparental types.\n\n\n[Illustration: FIG. 17\n\nDiagram showing the scheme of inheritance in guinea-pigs when black and\nalbino forms are crossed.]\n\n\n=Dominance Illustrated in Guinea-Pigs.--=In guinea-pigs for example (Fig.\n17), when an individual (either male or female) of a black variety, is\ncrossed with one of a white variety, the F_{1} generation are all black\nlike the black parent. When these are interbred or bred with other blacks\nwhich have had one black and one white parent, only two visible types of\nprogeny appear, viz., black and white, and these approximately in the\nratio of three to one.\n\nAnalysis by further breeding shows, however, that there are in reality\nthree types, but since dominance is complete the pure extracted dominant\nand the mixed dominant-and-recessive type are indistinguishable to our\neye. That is, while the blacks are three times as numerous as the whites,\ntwo out of every three of these blacks are really hybrid and correspond to\nthe blue fowls of our former example.\n\nThe condition is readily comprehended when expressed diagrammatically\nthus:\n\n  Generation P           Black x White       Black x White\n                               |                 |\n  Generation F_{1}        Black (White)  x   Black (White)\n                                         |\n                      +-------------------------------------+\n                      |                  |                  |\n  Generation F_{2}  1 Black       2 Black (White)       1 White\n\nIn other words, the germ-cells of the one original parent (Gen. P) would\ncontain only determiners for black and that of the other parent would\ncontain only determiners for white. The condition of the individuals\nproduced by the cross would be represented by the formula B(W). But these\ndeterminers segregate in the germ-cells of the crossed form, whether it be\nmale or female, into B and W. Hence half the spermatozoa of the male\nhybrid (generation F_{1}) would carry the B determiners and half the W\ndeterminers. The same is true of the mature ova of the female hybrid.\nConsequently, in mating there are always four equally possible\ncombinations, viz., BB, B(W), (W)B, and WW. Since B is always dominant\nthree out of the four matings would yield black individuals, or in other\nwords the ratio would be 3:1.\n\nThe pure blacks when mated together will breed true in subsequent\ngenerations, likewise the whites, but the blacks carrying white as a\nrecessive will yield when interbred the same ratio of whites and black as\ndid their hybrid parents (Fig. 17, p. 75).\n\n=Terminology.--=As work in the study of Mendelian inheritance has\nprogressed and expanded the need of a more precise terminology has become\nevident and such is gradually being established. Thus Professor Bateson\nhas coined the term \"allelomorph\" (Gk. _one another_, and _form_) to\nexpress more exactly what we have thus far been calling a pair of\nalternate or opposite characters. In the blue Andalusian fowls discussed,\nthe white condition in the one parent is the allelomorph of the black\ncondition in the other. The term generally means one of the pair of\nMendelian characters themselves as expressed in the individual plants or\nanimals but when the germinal basis of such phenomena is under discussion,\nit is sometimes used to refer to the determiners of such characters. And\nby determiner is meant simply the condition which is necessary in the germ\nto bring about the occurrence of a definite character. For example, when\nwe are studying a cross between a red flower and a white flower with\nreference to the color factors, the difference between the two plants may\nlie in the fact that one produces a red coloring matter and the other\ndoes not. That is, the determiner for red is absent from the white\nvariety. What the exact relation of color production is to the parts of\nthe germ-cell we do not know. It could be the function of a single\ndefinite body or the resultant of several cooperating bodies. The latter\nis far more likely to be the case. We may suppose that a group of\ncooperating substances function to produce red in the red flower but that\nin the white flowers one of these bodies is absent or fails to perform its\nred-producing function.\n\nIt is customary where practicable to refer to the determiner of a\ncharacter by the initial letter of the name of the character. The letter\nwhen written as a capital indicates the determiner but when written as a\nsmall letter the absence of the determiner. Thus R may be taken to\nrepresent the determiner for red coloring matter and r its absence. It is\nconvenient also to have a brief symbol to denote a given generation and\nfor this purpose Bateson has introduced the symbol F_{1} for the hybrid\nprogeny of the first cross, the initial letter of the word \"filial.\" F_{2}\nwould indicate the next generation, F_{3} the third and so on. Likewise P\ndenotes the original parent generation.\n\n=The Theory of Presence and Absence.--=Many, if not all, allelomorphs\nconsist of the presence and absence respectively of a given determiner. In\nsuch cases the character represented by the presence of the determiner is\ndominant over the character represented by the absence of a determiner.\nThus in the crosses from the wild gray mice and albino mice the progeny\nare all gray mice since one parent had the determiner or group of\ndeterminers for grayness and the hybrid offspring must also possess it.\nLikewise the presence of black in black guinea-pigs is dominant to its\nabsence in albino guinea-pigs and the resulting progeny are all black.\n\nHowever, it has already been mentioned that beardlessness in wheat is\ndominant to beard and that the absence of horns in cattle is dominant to\ntheir presence, that is, the progeny of hornless by horned cattle are\nwithout horns except for occasional traces of imperfect horns. Facts like\nthese would seem at first sight to contradict the assertion just made that\npresence is dominant to absence, but it is fairly well established that in\nsuch cases one is not dealing with true absences but with suppressions.\nThe polled breeds of cattle, for example, are hornless not because of the\nabsence of determiners for horns but because of the presence of an\nadditional inhibiting factor which prevents these determiners from\nfunctioning. The horned breeds are without this inhibitor. When horned and\nhornless individuals are crossed the presence of the inhibitor from one\nline of ancestry is sufficient to suppress the development of horns in the\nprogeny. A similar explanation would, of course, apply to beardlessness in\nwheat.\n\nIn writing double-lettered formulae to denote the determiners of characters\nin hybrids the condition is represented merely by the capital and small\nletter. Thus Rr indicates that red is dominant to its absence.\n\n=Additional Terminology.--=In pure breeds where the determiners are alike\nas BB in black or bb in albino guinea-pigs, the individual is said to be a\n_homozygote_ (like things united) with reference to that character, while\nin those in which the determiners are unlike, as Bb, the individual is\ntermed a _heterozygote_ (unlike things united) with reference to the\ncharacter. Or to use the adjective forms, a pure black guinea-pig is\nhomozygous for black pigment, an albino guinea-pig is homozygous for\nabsence of pigment, while a cross between the two is heterozygous for\npigment. Also, where the determiner of a given character is present in\ndouble quantity, that is, from both lines of ancestry, the individual is\nsaid to be _duplex_, where represented in only the single form as in\nheterozygous individuals, _simplex_, and where the determiner is absent\nentirely, _nulliplex_, with reference to the character in question. Thus\nblack guinea-pigs of formula BB are duplex with regard to the determiner\nfor black color, individuals of formula Bb are simplex with reference to\nthis determiner, and those of formula bb are nulliplex.\n\nA heterozygote in which dominance prevails can be identified with\ncertainty by breeding to a known recessive and noting the kind of\noffspring produced. If the individual was really a heterozygote,\napproximately fifty per cent. of the offspring should be of the recessive\ntype.\n\n=Dominance Not Always Complete.--=As a matter of fact close inspection\nshows that in numerous instances dominance is not absolute since traces of\nthe recessive character may be detectable. For example, in the cross\nbetween smooth and bearded wheat while smoothness is regarded as the\ndominant character and beardlessness as the recessive, nevertheless in the\nhybrid offspring a slight tendency toward bearding is not infrequently\nseen. Or again when horned breeds of cattle are crossed with hornless\nones, a small proportion of such progeny will show traces of imperfect\nhorns.\n\nIn some cases instead of either character dominating the other a form\nintermediate between the two parents may result, as we have seen already\nin the case of the Andalusian fowl. Thus, certain white-flowered plants\nand certain red-flowered plants when crossed produce pink hybrids, and\nlongheaded and shortheaded wheats when crossed give offspring with heads\nof intermediate length. Or again, crosses between white and red cattle may\nyield red roans, and between black and white cattle, blue roans.\n\nThus, while for such pairs of alternative characters as have been studied,\ndominance to some considerable degrees at least, seems to be the rule,\nstill we have gradations down to the intermediate condition, and in some\ninstances the hybrid with respect to a given character may be unlike\neither parent. The things of chief importance in the Mendelian discovery\nare the independent, unitary nature of the characters and their\nsegregation in the offspring of cross-bred forms.\n\n=Modifications of Dominance.--=It should be noted also that there is such\na condition as _delayed dominance_. Davenport found, for example, that\nchicks produced by crossing pure white with pure black Leghorn fowls are\nspeckled black and white, but later in the adult form white becomes\ndominant. Likewise conditions of delayed dominance are known in man in\neye-color and notably in color of hair. Some few cases have been recorded\nwhere a character is dominant at one time, recessive at another.\nAccording to Davenport extra toe in fowls may behave in this way.\n\n=Mendel's Own Work.--=Mendel[2] himself worked out his principles on seven\npairs of characters which he found in common culinary peas. Placing the\ndominant characters first, these may be enumerated as follows: (1) Tall by\ndwarf; (2) green pod (unripe) by yellow; (3) pod inflated by pod\nconstricted between the individual peas; (4) flowers arranged along the\naxis of the plant by flowers bunched together at the top; (5) seed skin\ncolored by seed skin white; (6) cotyledons yellow by cotyledons green; (7)\nseed rounded by seed wrinkled.\n\nHe found that each pair of characters followed the same law as any other\npair when more than one pair of the characters occurred in the same\nplants, but that each pair behaved independently of the other. The meaning\nof this is that we may get various combinations of characters not\nassociated in the original pure stocks, the number of such combinations\ndepending on the number of pairs of allelomorphs there are.\n\n\nDIHYBRIDS\n\n=Getting New Combinations of Characters.--=Since this principle is well\nillustrated in peas, let us take two pairs of their characters, viz.,\ngreenness and yellowness (of the cotyledons) and roundness and angularity\nto see exactly what happens when two pairs of allelomorphs are involved.\nWhen a specific kind of yellow pea is crossed with a particular kind of\ngreen pea the offspring are always yellow (Fig. 18, opposite p. 84). When\nthese hybrids (generation F_{1}) are self-fertilized there is the usual\nMendelian segregation; one-fourth the resulting offspring will be green,\none-fourth pure yellow, and one-half, although yellow in appearance, will\nbe of the mixed type. The exact numbers found by Mendel were 6,022 yellow\nseeds to 2,001 green seeds. Now of the original peas (generation P) the\nyellow ones are round and the green ones angular (really wrinkled).\nChoosing this roundness and angularity respectively as a pair of\ncharacters they are found to follow the same law that the colors follow\n(Mendel obtained in the F_{2} generation 5,474 round and 1,850 wrinkled\nseed), but independently of the latter. For while in the progeny of the\nhybrids (Gen. F_{1}), twenty-five per cent. will be round and of pure type\nas regards roundness, twenty-five per cent. angular, and fifty per cent.\nround but containing hidden factors of angularity (i. e., roundness is\ndominant), the roundness and the yellowness, or the angularity and the\ngreenness will not always go together as they did in the original\ngrandparental strains, but there will be in addition some new types of\nround green peas and some of angular yellow ones. That is, the factors of\ncolor and of shape have been inherited independently of one another, so\nthat instead of the two original kinds of peas, four have been produced,\nviz., (1) round-yellow (one of the original types); (2) round-green (new\ntype); (3) angular-yellow (new type); and (4) angular-green (one of the\noriginal types). Furthermore, these will be found to stand in the ratio of\n9:3:3:1 respectively.\n\n=Segregations of the Determiners.--=How these combinations come about in\nthis definite proportion is easily understood if the matter is expressed\nin terms of determiners and the possible matings tabulated (Fig. 18). If\nwe represent the yellow determiner by Y and the green determiner by y, and\nlikewise the determiners of roundness and angularity by R and r\nrespectively, then the formulae for the determiners of these two pairs of\ncharacters in the body cells (that is, in the unreduced condition) of the\npure forms and of the F_{1} generation hybrids respectively are as\nfollows:\n\n  In pure round yellow peas       RR YY\n  In pure angular green peas      rr yy\n  In the hybrid                   Rr Yy\n\nBut now in the segregation of these determiners in the germ-cells of the\nhybrids (generation F_{1}) the pair of determiners Rr and the pair Yy\noperate entirely independently of one another. Their only compulsion is\nthat each pair be separated into the single determiners, R and r in the\none case and Y and y in the other. So in the separating division which\nbrings about this divorcement R separates from r irrespective of whether\nit is accompanying Y or y into the resulting daughter cell. Thus in some\ncases R and Y would pass into one germ-cell, in others R and y, in others\nr and Y, and in still others r and y, depending entirely upon the\nchance relations of the respective pairs to the plane of division. That\nis, the segregation is equally likely to be RY/ry giving gametes RY and\nry, or Ry/rY giving gametes Ry and rY.\n\n\n[Illustration:\n\n       \\[Female]\n  [Male]\\   RY       Ry       rY       ry\n         +-------+--------+--------+--------+\n    RY   | RRYY  |  RRYy  |  RRYY  |  RrYy  |\n         +-------+--------+--------+--------+\n    Ry   | RRYy  |  RRyy  |  RrYy  |  Rryy  |\n         +-------+--------+--------+--------+\n    rY   | RrYY  |  RrYy  |  rrYY  |  rrYy  |\n         +-------+--------+--------+--------+\n    ry   |  RrYy |  Rryy  |  rrYy  |  rryy  |\n         +-------+--------+--------+--------+\n\n      (1) 1 RRYY    (4) 2 RrYY    (7) 1 rrYY\n      (2) 2 RRYy    (5) 4 RrYy    (8) 2 rrYy\n      (3) 1 RRyy    (6) 2 Rryy    (9) 1 rrYy\n                      9:3:3:1\n\nFIG. 18\n\nDiagram showing the possible combinations arising in the second filial\ngeneration (F_{2}) following a cross between yellow, round (YYRR) and\ngreen, angular or wrinkled (yyrr) peas. Y, presence of factor for yellow;\ny, absence of such a factor; R, presence of factor for smoothness or\nroundness; r, absence of such a factor; [male] male; [female] female.]\n\n\n=Four Kinds of Gametes in Each Sex Means Sixteen Possible\nCombinations.--=There are, therefore, with reference to the two pairs of\ncharacters under consideration, four kinds of gametes (or mature\ngerm-cells) produced in equal numbers in each hybrid, viz., RY, Ry, rY,\nand ry. That is, in the first type roundness and yellowness are\nassociated, in the second roundness and greenness, in the third angularity\n(lack of roundness) and yellowness, and in the fourth angularity and\ngreenness.\n\nBut since both males and females have these four kinds of gametes, when\nthey are mated there will be sixteen possible combinations. These may be\ntabulated as in Fig. 18, opposite p. 84.\n\n=The 9:3:3:1 Ratio.--=While there are sixteen possible and equally\nprobable combinations, these will give only nine distinct kinds because\nsome of the matings are alike. The numbers of the various kinds of matings\nare as follows:\n\n  (1) 1 RRYY    (4) 2 RrYY    (7) 1 rrYY\n  (2) 2 RRYy    (5) 4 RrYy    (8) 2 rrYy\n  (3) 1 RRyy    (6) 2 Rryy    (9) 1 rrYy\n\nSince roundness (R) and yellowness (Y) are dominant to angularity (r) and\ngreenness (y) in all combinations containing R or Y, the alternative\ndeterminers r or y would be obscured, with the result that individuals\nhaving certain of the combinations would look alike to our eye. For\nexample, the individuals represented by numbers 1, 2, 4 and 5, since they\ncontain dominant R and Y, would all appear round and yellow, although in\nreality No. 1 would be the only one of pure type (both elements\nhomozygous) and hence the only one that would breed true in subsequent\ngenerations. The two individuals represented in No. 2 would breed true as\nregards shape (RR) but not color (Yy). Just the reverse is true of No. 4\nsince shape is heterozygous (Rr) and color homozygous (YY). The four\nindividuals represented in No. 5 are heterozygous with regard to both\nelements. Thus nine individuals (1 plus 2 plus 2 plus 4 = 9) represented\nin Nos. 1, 2, 4 and 5 would be round and yellow, three individuals (Nos. 3\nand 6) would be round and green, three (Nos. 7 and 8) would be angular and\nyellow, and only one (No. 9) would be angular and green. That is to say,\nthe four classes discernible to the eye in generation F_{2} would be\npresent in the ratio of 9:3:3:1.\n\n=Phenotype and Genotype.--=Forms such as those represented in Nos. 1, 2, 4\nand 5 which to the eye appear to be alike, regardless of their germinal\nconstitution, are said to be of the same _phenotype_. Those of the same\nhereditary constitution, as the two individuals represented in No. 8, or\nthe four individuals in No. 5, are said to be of the same _genotype_, that\nis, they are of identical gametic constitution.\n\nAs we have seen, it is from the genotypical not the phenotypical\nconstitution that an offspring is derived and what a given form will bring\nforth depends then on its genotype.\n\n=Crosses With More Than Two Pairs of Characters.--=In crosses in which\nmore than two pairs of contrasted characters are involved the underlying\nprinciples are in no way different, only with each pair of additional\ncharacters there is, of course, a greater number of possible combinations.\nThus with three pairs of characters there will be eight different classes\nof gametes in each sex and consequently sixty-four possible combinations\nin mating, giving eight different phenotypes in the proportion of\n27:9:9:9:3:3:3:1. The largest class manifests the three dominant\ncharacters; the smallest class, the three recessives; the three classes in\nthe proportion of 9 each exhibit two dominant and one recessive\ncharacters; and those in the proportion of 3 each display two recessive\nand one dominant characters.\n\n\nTHE QUESTION OF BLENDED INHERITANCE\n\nWe come now to certain types of inheritance in which there seems to be a\ntrue fusion or blend of the contributions from the two parents, the\nintermediate condition apparently persisting in subsequent generations\nwithout segregation. Numerous cases of blended inheritance have been cited\nin earlier literature of heredity, but as our knowledge of genetics has\nprogressed many experimental breeders have come to believe that the\nblends in such cases are apparent rather than real and that the phenomena\ncan be best explained on a non-blending unit-character basis, just as we\nwould explain ordinary Mendelian phenomena.\n\n=Nilsson-Ehle's Discoveries.--=To get their point of view we may review\ncertain experiments on wheat made by Nilsson-Ehle, together with their\nMendelian interpretation. Nilsson-Ehle found that a certain brown-chaffed\nwheat when crossed with a white-chaffed strain yielded a brown-chaffed\nhybrid, apparently in accordance with the simple principle of Mendelian\ndominance. But these heterozygous brown-chaffed individuals did not in\nturn give the expected ratio of 3:1 in the F_{2} generation but a ratio of\n15 brown to 1 white, and furthermore the browns were not all of the same\ndegree of brownness. To be exact, from fifteen different crosses of the\nstrains he obtained 1,410 brown-chaffed and 94 white-chaffed plants.\n\nThis apparent anomaly in segregation was easily explained, however, when\nit was finally figured out that there were really two independent\ndeterminers for brown color, either of which alone could produce a brown\nindividual, but when combined produced individuals of correspondingly\ndeeper shades of brown. In such a case then Nilsson-Ehle discovered that\nhe was dealing merely with a Mendelian dihybrid where two different\ndeterminers B and B' and their respective absences b and b' are involved.\nThe original brown wheat had both B and B' and the original white b and\nb'. The formula for the F_{1} heterozygote was therefore BbB'b'. The four\npossible types of gametes for male and female are BB', Bb', bB', bb', and\nthe tabulation would be as follows:\n\n       +-----------------------------------\n       |  BB'   |  Bb'   |  bB'   | bb'\n  -----+--------+--------+--------+--------\n   BB' | BBB'B' | BBB'b' | BbB'B' | BbB'b'\n  -----+--------+--------+--------+--------\n   Bb' | BBB'b' | Bb'Bb' | BbB'b' | Bbb'b'\n  -----+--------+--------+--------+--------\n   bB' | BbB'B' | BbB'b' | bbB'B' | bbB'b'\n  -----+--------+--------+--------+--------\n   bb' | BbB'b' | Bbb'b' | bbB'b' | bbb'b'\n  -----------------------------------------\n\nIt will be observed that there are more brown determiners in some\ncombinations than others. For instance one of the sixteen contains four\nsuch determiners, viz., B, B', B, B', four contain three determiners, six\ncontain two, four contain only one, and one contains none. Thus all but\none of the sixteen contain at least one determiner and will therefore be\nbrown in color but the depth of color will depend on the number of brown\ndeterminers in a given individual. This is more graphically represented in\nFig. 19, p. 90. The largest number of similar individuals, six in all,\ncontain two determiners each and represent an intermediate \"blend\" between\nthe original brown-chaffed and white-chaffed strains. The deeper and the\nlighter browns due to more or fewer determinants in an individual would if\none did not know the units in this case look like the fluctuations around\nthis average which we might expect in a blend.\n\n\n[Illustration: FIG. 19\n\nDiagram illustrating the proportionate distribution of determiners where\neither of two different determiners produces the same character, the\ndegree of expression of the character depending on the number of the\ndeterminers present. The numerals indicate the number of brown determiners\npresent in an individual.]\n\n\nNilsson-Ehle found another significant case in wheat where one particular\nred-grained strain of Swedish wheat when crossed with white-grained\nstrains produced red-grained offspring, but when these were interbred the\nF_{2} generation gave approximately sixty-three red to one white-grained\nindividual. Here it was found that in the original red wheat there are\nthree separate determiners which act independently of one another in\nheredity, any one of which would make red color; and that they together\nwith their absences simply follow the Mendelian laws for a trihybrid.\n\n=Such Cases Easily Mistaken for True Blends.--=If we should tabulate the\npossible combinations as we did the dihybrid we should see that we would\nget individuals having varying numbers of red determiners. Only one of the\nsixty-four possible combinations would be without a factor for red. Of the\nsixty-four, one would have six determiners for red, six would have five,\nfifteen would have four, twenty would have three, fifteen would have two,\nsix would have one, and one would have none. Since here every additional\nred factor means deeper redness in the individual there would be varying\ndegrees of redness in the F_{2} generation with those having three\ndeterminers, the largest group, standing apparently intermediate. Not\nknowing the factors involved we might easily mistake such a case for a\ntrue blend with fluctuations about an average intermediate form.\nNilsson-Ehle finally proved his interpretation by rearing an F_{3}\ngeneration from isolated and self-fertilized plants of this F_{2}\ngeneration.\n\nThis same principle of cumulative determiners has also been established in\nAmerica by East with field corn.\n\nAs the number of duplicate determiners increases it can be readily seen\nthat the number of apparent blends of different degrees of intermediacy\nbetween the two extremes would rapidly increase.\n\n=Skin-Color in Man.--=In man, the skin-color of the hybrids between\nnegroes and whites is often cited as a case of blended inheritance in\ncontradistinction to Mendelian inheritance. The skin-color of the mulatto\nof the F_{1} generation is intermediate between that of the white and\nblack parent. This same degree of intermediacy is commonly supposed to\npersist in subsequent generations, but as a matter of fact, careful\ninvestigation has shown that while mulattoes rarely produce pure white or\npure black children, there is considerably greater range in the shades of\ncolor in the F_{2} generation and subsequent generations than in the F_{1}\ngeneration. This is exactly what one would expect of a Mendelian character\nin which several cooperating factors were involved. Indeed, Davenport who\nhas made extensive studies[3] on the inheritance of skin-color in man has\ncome to the conclusion that the case is really one of Mendelian\ninheritance in which several factors for skin-color are concerned. Even\nthe skin of a white man is pigmented in some degree under normal\nconditions. Davenport has shown in the skin of both whites and blacks that\nthere is a mixture of black, yellow and red pigments. He concludes that\n\"there are two double factors (AABB) for black pigmentation in the\nfull-blooded negro of the west coast of Africa and these are separably\ninheritable.\" Since these factors are lacking in white persons the\nintermediate color of an F_{1} mulatto would therefore be heterozygous for\npigmentation, and subsequent generations, following the laws for\nsegregation where a number of factors are concerned, would show different\ndegrees of color because of the varying combinations of factors.\n\n=Some Investigators Would Question the Existence of Real Blends.--=Still\nother reputed blends such as ear length in rabbits and the like have been\nshown to be analyzable into Mendelian behavior if one will but postulate\nnumerous or multiple factors. Just how far we are justified in so\naccounting for blends has not yet been established. Some of our most\ncareful experimentalists in heredity still believe that real blends exist,\nparticularly where the character is quantitatively expressed--that is, as\nmore or less of a given size or amount--while others would maintain that\nall alleged blends will probably be found to be resolvable into factors\nwhich follow Mendelian rule. It must be left for future investigations to\ndemonstrate which school is correct.\n\n\nTHE PLACE OF THE MENDELIAN FACTORS IN THE GERM-CELLS\n\n=Parallel Between the Behavior of Mendelian Factors and Chromosomes.--=The\nquestion arises as to whether there is any evidence from the study of\ngerm-cells themselves to bear out the Mendelian conception of separation\nof contrasted characters in the gametes of the F_{1} generation. In the\ndiscussion of the maturation of germ-cells (Chap. II) it has already been\nseen that the chromosomes of the germ-cells are in all probability\narranged in homologous pairs, one member being of maternal and the other\nof paternal origin, and that furthermore they are closely associated with\nthe phenomena of heredity. And since in maturation there is an actual\nsegregation of the chromosomes into two sets, half going to one cell and\nhalf to its mate, a physical basis adequate to the necessities of the case\nis really at hand. It will be recalled that the individuals of a pair\nseparate in such a way at the reduction division that the paternal member\ngoes to one cell and the maternal member to the other, although each pair\nseemingly acts independently of the others with the result that any mature\ngerm-cell may contain chromosomes from each of the original parents but\nnever the two chromosomes which earlier made up a pair. The close parallel\nbetween the behavior of chromosomes and the behavior of Mendelian factors,\nalthough the two sets of phenomena were discovered wholly independently of\neach other, is obvious. If we suppose that each chromosome bears the\ndeterminer of a Mendelian character and that chromosomes bearing\nallelomorphic characters make up the various pairs which are seen in the\nearly germ-cells of an individual before reduction occurs, then the\nsegregation of the individuals of an allelomorphic pair into different\ngametes must result in consequence of the passing of the corresponding\nchromosomes into separate gametes. Fig. 20, p. 95, from Professor Wilson\nrepresents equally well the segregations of pairs of chromosomes or pairs\nof Mendelian characters.\n\n\n[Illustration: FIG. 20\n\nDiagram showing union of factors from the two separate parents in\nfertilization and their segregation in the formation of germ-cells (after\nWilson). With four pairs of factors (_Aa_, _Bb_, _Cc_, _Dd_), sixteen\ntypes of gametes are possible, as shown in the series of small circles at\nthe right. The same diagram equally well represents the pairings and\nsegregations of chromosomes.]\n\n\n=A Single Chromosome not Restricted to Carrying a Single Determiner.--=It\nhas been objected that there may be more pairs of independently heritable\nallelomorphic characters than there are pairs of chromosomes. It is true\nthat there are more pairs of characters than pairs of chromosomes but\nthere is no reason for supposing that a given chromosome is restricted to\ncarrying a single unit-determiner. On the contrary it probably carries\nseveral or many. Some workers have pointed out that certain units might be\ninterchanged during the pairing of chromosomes before the reduction\ndivision, others that inasmuch as the chromosomes become diffuse and\ngranulated during the intervals between divisions it is not improbable\nthat the individual units may become separated from their original system\nduring such times and that it is a matter of chance into which of the\nhomologous chromosomes, A or a, they enter with the re-establishment of\nthe chromosomes. On the other hand, cases are known where two or more\nseparate characters are permanently associated in inheritance, that is, if\nthey enter a crossed form together they come out together in the\ngrandchildren as if they were carried in the same unit-body in the\ngerm-cell. The only observable unit-bodies that fulfil the necessities of\nsuch cases are the chromosomes. This tendency of characters to exist in\ngroups which are inherited independently of one another is coming more and\nmore into evidence as we penetrate farther into the intricacies of\ninheritance, and it is exactly what we would expect on the supposition\nthat each chromosome carries the determiners of a number of characters\ninstead of a single one.\n\n\n\n\nCHAPTER IV\n\nMENDELISM IN MAN\n\n\n=The Mendelian Principles Probably Applicable to Many Characters of\nMan.--=We are really just beginning to make the proper observations and\ncollect the necessary data with reference to the application of Mendelian\nprinciples to the traits of man. Yet brief as has been our study we have\ndisclosed much significant evidence which makes it seem highly probable\nthat many of his characters, good and bad, of mind and body are as\nsubservient to these laws as are the traits and features of lower forms.\nDavenport and Plate record over sixty human characters or defects which\nare seemingly inherited in Mendelian fashion. Although about fifty of\nthese are pathological or abnormal conditions, this does not mean that\nsuch conditions are more prone to follow Mendelian inheritance but merely\nthat being relatively conspicuous or isolated they are easier to follow\nand tabulate.\n\n=Difficult to get Correct Data.--=While it must be said that in many cases\nno simple form of Mendelian tabulation has been unequivocally established,\nyet the general behavior of the various inheritable traits in question is\nso obviously related to the conventional Mendelian course that there seems\nlittle reason for doubting that they are at bottom the same. Failure to\nobtain exact proportions may be attributable in part to the probability\nthat what we loosely regard as a character should in reality be analyzed\ninto more elemental components, and above all to the fact that from the\nvery nature of the conditions under which human records must be obtained,\nthere is considerable chance of inaccuracy or error in such accounts. How\nmany human traits follow Mendelian rules remains largely for future\ninvestigators to establish.\n\nWe are handicapped at the outset in man by the many difficulties of\ngetting correct data from the genealogies on which we must depend, or in\nfact of getting any genealogy at all, for in this country at least, most\nfamilies keep imperfect records of births and deaths and many of the\ninstitutions for the various kinds of defectives have little in their\nrecords that will help us in following out hereditary conditions. Then in\nmatters of disease we meet with the fact that many former diagnoses were\nerroneous. In yet other cases, and this is particularly true among mental\nand moral defectives, we are often not sure of the paternity of a given\nchild. Furthermore, one is likely to be misled by the proportions which\nmay occur in the very limited number of children of any given couple.\n\nStill other difficulties exist. Among these is the fact, for example, that\nin many cases of defect or susceptibility to disease, a given individual\nin the stock may have the trait in an expressible and transmissible form,\nyet it never comes to expression because that individual has been\nfortunate enough to escape the environmental stimulus which would call it\nforth. Thus one highly susceptible to tuberculosis might escape infection,\nor persons hovering on the verge of insanity might never receive the\nprecipitating stimulus which would topple them into actual insanity; yet\neach would be wrongfully recorded in a genealogy looking to such traits as\nperfectly normal. Or again if it be a question of intellectual brilliancy\nas shown by accomplishment in the realm of scholarship, or of worldly\naffairs, the ones who although possessing them have had no chance to\ndisplay unusual talents would be tabulated as average whereas in fact they\nshould be recorded as of high rank. That this is particularly likely to\nhappen in the case of women is evident.\n\n=A Generalized Presence-Absence Formula for Man.--=In man as in lower\nforms some characters or traits are due presumably to the presence of\ndeterminers or to their absence. Likewise, dominance and recessiveness are\nas much in evidence, for in tracing back pedigrees of various traits we\nfind the same forms of tabulation that obtain for these conditions in\nplants and lower animals hold good. For typical cases in man let us use a\ngeneralized presence-absence formula and the arbitrary symbol A for the\npresence of the determiner of the character (double in the individual,\nsingle in the germ) and a for its absence. Thus AA represents a condition\nin which similar determiners have been derived from both parents and the\nindividual is _duplex_ as regards the character in question; each mature\ngerm-cell will have the determiner. Aa represents a condition in which the\nindividual has received the determiner from only one parent and is\ntherefore _simplex_ with regard to the character; half of the gametes of\nsuch an individual will have the determiner and half will lack it. Lastly,\naa represents total absence of the determiner. Such an individual is\n_nulliplex_. He or she will not have the determiner represented in any of\nthe gametes, and can not, of course, transmit a trait represented by the\ndeterminer.\n\nIt is evident that six kinds of gametic matings are possible among\nindividuals representing these various formulae. These matings are as\nfollows:\n\n                                        Possible\n                                        couplings\n          Matings                      of gametes       Product\n\n  1. Nulliplex x Nulliplex (aa x aa) == a------a == all nulliplex\n                                           \\/\n                                           /\\\n                                        a------a\n\n  2. Nulliplex x Simplex (aa x Aa)   == a------A == 50 per cent.\n                                           \\/       with character\n                                           /\\       nulliplex and\n                                        a------a    50 per cent.\n                                                    with it\n                                                    simplex.\n\n  3. Nulliplex x Duplex (aa x AA)    == a------A == all with characters\n                                           \\/       simplex\n                                           /\\\n                                        a------A\n\n  4. Simplex x Simplex (Aa x Aa)     == A------A == 25 per cent.\n                                           \\/       with characters\n                                           /\\       duplex, 50 per\n                                        a------a    cent. with it\n                                                    simplex and 25\n                                                    per cent. with\n                                                    it nulliplex.\n\n  5. Simplex x Duplex (Aa x AA)     == A-------A == 50 per cent.\n                                          \\/        with character\n                                          /\\        duplex and 50\n                                       a-------A    per cent. with\n                                                    it simplex.\n\n  6. Duplex x Duplex (AA x AA)      == A-------A == all duplex.\n                                          \\/\n                                          /\\\n                                       A-------A\n\n=Indications of Incomplete Dominance.--=While in cases of strict Mendelian\ndominance it is not possible to distinguish directly the simplex from the\nduplex condition, as a matter of fact the individual of simplex\nconstitution sometimes has the character represented in the single\ndeterminer less perfectly developed than in the corresponding character of\nduplex origin. In studying defects in man due to the absence of a\ndeterminer, where theoretically presence of the determiner (normality) is\ndominant over its absence in individuals of simplex constitution, one\nfinds it recorded with increasing frequency that such individuals are more\nor less \"intermediate\" or are \"tainted\" with the defect; thus showing that\nthe defect though obscured is not wholly in abeyance. Thus individuals\ncarrying epilepsy or feeble-mindedness which are regarded as recessive\ntraits, while not showing specific feeble-mindedness or epilepsy, may\nnevertheless apparently show a neuropathic taint in the form of migraine,\nalcoholism or other lapse from normality. The condition is seemingly more\nakin in some cases to that found in the offspring of certain red flowers\ncrossbred with white flowers, which though red do not show the same\nintensity of color as the original red parent. Just as here the single\ndeterminer or single \"dose\" of redness is insufficient to produce the\nintensity of color that appears when the offspring receive two determiners\nfor red, one from each parent, so in man a single determiner for normality\nof a specific character is inadequate in some cases to make the individual\nwholly normal. Or possibly some cases are more of the type of those in\nwhich the character in question, for instance the red color of some wheats\nand corn, may be produced by any one of two or three determiners, the\nintensity of the characters (red color, e. g.) depending on whether one,\ntwo or three determiners are present.\n\n=Why After the First Generation Only Half the Children May Show the\nDominant Character.--=If the trait is a simple dominant one it is clear\nthat it will appear in each generation and always spring from an affected\nindividual. By referring back to our tabulation of possible matings on\npage 100 where the dominant character is represented by the letter A, this\ncan be seen at a glance. If the trait is present in the duplex condition\nin one parent and absent from the other, then formula 3 applies; all\nchildren will show the trait, but in the simplex form (Aa). If the trait\nis present in the simplex form in one parent and absent in the other,\nformula 2 applies. Fifty per cent. of the children will have the character\nin the simplex form (Aa) which means also an even chance of transmitting\nit to their offspring; fifty per cent. will not inherit it and will be\nincapable, furthermore, of transmitting it, since they have become\nnulliplex (aa). In human genealogies if an individual having an unusual\ntrait which is inherited as a dominant marries a normal person and half of\nthe offspring show the trait (and this is common), this means that the\nparent manifesting the trait had it represented only in the simplex\ncondition, otherwise all of the children would have shown it. Even though\nthe original ancestor who first developed the condition or structure may\nhave had it in a duplex form, it would after the first mating, if this\nwere with an individual lacking the trait, be represented only in the\nsimplex form (see formula 5) and could never become duplex again unless\ntwo individuals both having the character married, and then only in\ntwenty-five per cent. of the offspring (see formula 3). If the trait is a\ndefect all the children showing it, even though marrying normal\n(nulliplex) individuals, will pass it on again to half their children, but\nthose who do not show it may ordinarily marry with impunity since its\nnon-expression in their make-up means, as far as we know at present, that\ntheir germ-plasm has been purged of the defect and that they are therefore\nnulliplex with reference to it.\n\n=Eye-Color in Man.--=Of normal characters in man which follow the\nMendelian formula perhaps eye-color is the best established. Brown or\nblack eye-color is due to a _melanin_ pigment absent from the blue or gray\neye. That is, a brown eye is practically a blue eye plus an additional\nlayer of pigment on the outer surface of the iris. The different shades of\nbrown and the black are due to the relative abundance of this pigment.\nGray color and the shades of blue seem to be a modification of an original\ndark blue, due to structural differences in the fibrous tissues of the\niris.\n\nIn inheritance brown or black is dominant to blue or gray, or in other\nwords the _presence_ and _absence_ of a pigment P constitutes a pair of\nallelomorphs. Hence two brown-eyed parents, if P is duplex in both (or\nduplex in one and simplex in the other) can have only brown-eyed children.\nThus,\n\n  1. PP x PP = PP, or all duplex brown.\n\n  2. PP x Pp = PP and Pp, half duplex brown and half simplex brown.\n\nIf each parent has brown eyes but in simplex condition, then one-fourth\nof children will have blue or gray eyes; for example,\n\n  Mating   Gametic              Product\n          couplings\n\n  Pp x Pp = P--P   =  PP, Pp, pP, and pp, or one-fourth\n             \\/       duplex brown, one-half simplex\n             /\\       brown, and one-fourth blue or\n            p--p      gray.\n\nIf both parents have blue or gray eyes they can not have children with\nblack or brown eyes, since the recessive condition in each parent means\ntotal absence of brown pigment in both.\n\nIf one pair is duplex brown and the other blue, then all children will\nhave brown eyes but of simplex type.\n\nIf one parent has simplex brown eyes (type Pp) and one blue (pp) then\none-half of the children will have brown eyes of simplex type and one-half\nwill have blue eyes.\n\nOccasional objections have been raised against the Mendelian\ninterpretation of inheritance in eye-color, but the cases cited in\nevidence against the theory usually narrow down to those in which the\ncolor is so diluted as to render classification uncertain. For example,\nhazel eyes are sometimes called gray; they belong however to the melanic\npigmented type although the brown pigment may be much diluted and occur\nmainly around the pupil. So-called green eyes are due to yellow pigment on\na blue background. In the rare cases where in the same individual one eye\nis brown and the other blue, the individual should probably be rated as\nbrown-eyed on the supposition that in the one eye the development of brown\npigment has in some way been suppressed.\n\n=Hair-Color.--=The inheritance of hair-color has also been the subject of\nconsiderable study and while the conditions are not so simple as in the\ncase of eye-color, there is little doubt that it belongs in the Mendelian\ncategory. In human hair, color has as its foundation apparently two\npigments, black and red. Absence of one or both or various combinations or\ndilutions of these seemingly account for the prevailing colors in human\nhair. In general dark hair is dominant to light, although because of the\ndelay sometimes in the darkening of the hair in children this fact is\noften obscured. Black is dominant to red. People with glossy black hair,\naccording to Davenport, are probably simplex for black, the glossiness\nbeing due usually to recessive red. The expectation would be for some of\nthe children of such a pair to have red hair.\n\nIn man occasionally a congenital white lock contrasting strikingly with\nthe remaining normally pigmented hair occurs. It behaves as a simple\ndominant in heredity.\n\n=Hair-Shape.--=Again, straight and curly hair seem to be distinct\ninheritable characters. Curly is incompletely dominant to straight, the\nsimplex condition yielding wavy hair.\n\nNot to enter into details of the matings, statistics gathered by Mr. and\nMrs. Davenport show that, two flaxen-haired parents have flaxen-haired\nchildren; two golden-haired parents have only golden-haired children; two\nparents with light brown hair have children with hair of that color or\nlighter, but never darker; two parents each with dark brown or black hair\nmay have children with all the varieties of hair-color. Summing together\na series of recessives Davenport points out that two blue-eyed, flaxen or\ngolden and straight-haired parents will have only children like\nthemselves.\n\n\n[Illustration: FIG. 21\n\nDiagram showing descent of brachydactyly through five generations; black\nsymbols indicate affected individuals; [male], male; [female], female\n(after Farabee).]\n\n\n=Irregularities.--=If a dominant trait or defect depends on more than a\nsingle factor, as is sometimes the case, or if it is modified by sex or\nother conditions, as is true of certain characters, some of which, such as\ncolor-blindness, have already been examined, then we shall find some\napparently non-affected individuals having affected offspring. Certain\ndiseases, for example, are generally transmitted by affected members of\nthe family to their children in the expected Mendelian ratio for a\ndominant, yet an occasional skip of a generation may appear in which an\napparently perfectly normal individual transmits to his children what,\nexcept for the omission in his own case, appears to be an ordinary\ndominant character. This occasional lapse in the appearance of a\ncharacter when theoretically it should appear is doubtless due in some\ninstances to the fact that what is really inherited is a _tendency_, and\nalthough this is present in the apparently normal individual, for some\nreason the condition itself has not appeared. This might especially be\ntrue in the case of a disease which does not manifest itself until late in\nlife. In other cases there are undoubtedly complicating accessory\nconditions which modify the behavior of the trait somewhat.\n\n\nOTHER CASES OF DOMINANCE IN MAN\n\nAmong other normal characters in man, as far as available evidence goes,\ndark skin is dominant to light skin; normally pigmented condition to\nalbino; and nervous temperament to phlegmatic.\n\n=Digital Malformations.--=An interesting and easily followed defect is a\ncondition known as _brachydactylism_, in which the digits are shortened\nbecause of the absence or rudimentary condition of one segment. The\nfingers, therefore, appear to be only two-jointed like the thumb. Several\nfamilies showing this defect have been charted and it appears to behave as\na typical dominant. In looking over such a chart (Fig. 21, p. 106) one is\nstruck by the fact that only half of the children from most of the matings\nshow the defect, but when we recall that the affected parent, after the\nfirst generation, probably carried the condition in only the simplex form\nand married a normal individual, such a result is just what would be\nexpected (see formula 2).\n\n_Polydactylism_ (Figs. 22, 23, pp. 109, 110) is a condition in which there\nare extra digits on hands or feet. The character, with apparently slight\nexceptions in a few records, behaves as a typical dominant. Among other\ndigital defects which are inherited as a dominant is a condition known as\n_syndactylism_ (Fig. 24, p. 111), in which two or more digits are fused\nside by side. For an example of syndactyly which seems to be in the class\nof sex-linked characters, see Fig. 15, p. 65.\n\n=Eye Defects.--=_Congenital cataract_ is another not uncommon defect in\nman which is transmitted as a dominant (Fig. 25, p. 112) with occasional\nirregularities. It is a condition of opacity of the lens of the eye which\nproduces partial or total blindness. In a paper on _Hereditary Blindness\nand Its Prevention_, Clarence Loeb (1909) mentions 304 families of which\npedigrees have been published. Of the 1,012 children in these families\n589, or 58 per cent., were affected. It is obvious that this is near the\nexpected percentage in the case of a dominant trait where matings of\naffected with normal individuals prevailed. An unfortunate circumstance\nabout this malady from the eugenic standpoint is the fact that it is\nfrequently of the presenile form which comes on late in life so that it is\nusually impossible to predict whether an individual of marriageable age is\nimmune or will later become affected.\n\n\n[Illustration: FIG. 22\n\nRadiograph (Courtesy of Dr. W. B. Helm) showing polydactyly in a child's\nhand. For genealogy of this see Fig. 23, p. 110.]\n\n\n[Illustration: FIG. 23\n\nChart showing a history of polydactylism through five generations in the\nB---- family. The individual whose hand is pictured in Fig. 22, p. 109, is\nof the fifth generation. Squares represent males, circles females.]\n\n\nAnother defect of the eye following the course of a dominant in heredity\nis a pigmentary degeneration of the retina known as _retinitis\npigmentosa_. Atrophy of the optic nerve is also involved and the final\nresult is blindness. Still another example frequently cited is that of\nhereditary night blindness (_hemeralopia_), a disease in which the\naffected person can not see by any but the brightest light. In most\naffected families the final outcome is usually total blindness. One of the\nmost remarkable pedigrees of defects in man ever collected is one of this\ndisease published by Nettleship. He succeeded in tracing the defect\nthrough nine generations, back to the seventeenth century. The genealogy\nincludes 2,116 persons. The character behaves as a single dominant in\nmales, but frequently, though not always, females may be carriers of the\ndefect in transmissible form though not exhibiting it themselves. That is,\nmales in which the condition is simplex (Aa) develop the defect but\nfemales of similar simplex constitution (Aa) frequently do not. It\nfollows, therefore, that normal males of such strains will have normal\noffspring but normal females may have affected children.\n\n\n[Illustration: FIG. 24\n\nRadiograph (Courtesy of Dr. W. B. Helm) showing a partial syndactyly in\neach hand of an individual. Some degree of webbing between the more distal\nportions of the affected parts is usual.]\n\n\n[Illustration: FIG. 25\n\nPedigree of a family with presenile cataract (black symbols); numbers in\ncircles indicate unaffected individuals (after Davenport).]\n\n\n=Other Defects Inherited as Dominants.--=Not to go into details other\ndefects which behave as dominants or modified dominants in human\ninheritance may be mentioned. The following list is not complete and it\nmust be understood that in some cases the statistics are insufficient to\njustify us in making anything but a tentative decision. We may thus\nenumerate as dominant over normality: _Achondroplasy_ (abnormally short\nlimbs with normal head and body); _Keratosis_ (thickening of epidermis);\n_Epidermolysis_ (excessive formation of blisters); _Hypotrichosis_\n(hairless, toothless condition); _Diabetes insipidus_; _Diabetes\nmellitus_; ordinary (not Gower's) _muscular atrophy_; _Glaucoma_ (internal\nswelling and pressure of eye-ball); displaced lens; _Coloboma_ (open\nsuture in iris); spottedness of hair-coat; and corneal opacity.\n\nAs a final illustration of a serious malady in man which acts as a\ndominant in inheritance, let us take _Huntington's chorea_. Ordinary\n_chorea_, or St. Vitus' dance, a disorder characterized by involuntary\nmuscular movements, is commonly though not always confined to children and\nusually ends in recovery, but _Huntington's chorea_ appears typically in\nmiddle life and is a much more dangerous malady. Fig. 26, p. 114,\nrepresents the family history of one of five cases which have been studied\nby Doctor Lorenz in the Mendota Hospital for the Insane. All charts which\nhave been platted of this malady show it to be inherited as a dominant.\nThis means that half of the children of an individual who carried the\nmalady in the simplex condition, and all the children of one who carries\nit in the duplex condition, are probably marked for this terrible end. And\nthe true horror of it can only be appreciated by one who has seen the last\nstages of the malady. The victim once in its grasp gradually becomes\nwrecked in mind and body; the muscular twitchings and disorders of\nmovement continually increase and dementia progresses until at last death\nensues. Fig. 27, p. 115, is another chart showing inheritance of\n_Huntington's chorea_. In still a third case at the Mendota Hospital, the\ngravity of the situation can be appreciated when one realizes that the\npatient is the father of ten children, ranging in age from one to\nseventeen and one-half years. The calamitous fact that this disease does\nnot manifest itself usually until middle life makes it likely that these\nchildren will all reach maturity, marry and in turn probably produce\noffspring before the doomed members of the family realize their fate.\n\n\n[Illustration: FIG. 26\n\nChart showing descent of _Huntington's chorea_ in the P---- family\n(courtesy of Dr. W. F. Lorenz). Squares represent male, circles female;\nshaded figures are choreic members of the family; partially shaded\nfigures, slightly affected or very \"nervous\" members. The members of the\nlast generation are for the most part still too young to show their\ncondition. The cross indicates the individual in the asylum from whom the\nrecord was traced back.]\n\n\nCASES OF RECESSIVENESS IN MAN\n\n=Recessive Conditions More Difficult to Deal With Because They Are\nFrequently Masked.--=Coming now to the question of recessive conditions in\nman, we find that defects are more likely to be of recessive than of\ndominant type. Apparently normality usually means the presence of normal\ndeterminers and abnormality, the absence of some essential determiner. In\nthe latter case, a unit-factor has seemingly been lost out in some way in\nthe germ-plasm, and the product of such germ-plasm is therefore\nincomplete. As long as the loss is counterbalanced by the presence of a\nsingle determiner from the other line of ancestry, that is, as long as the\nsimplex (Aa) condition prevails, the loss may not be in evidence, except\nin cases of incomplete dominance (taints, etc.), but any mating which\npermits of the production of the nulliplex condition will bring the defect\nto expression again.\n\n\n[Illustration: FIG. 27\n\nChart showing inheritance of _Huntington's chorea_ in the R---- family\n(courtesy of Dr. W. F. Lorenz); 1, 2 have been patients at Mendota\nHospital for the Insane; 3, died of \"paralysis\"; the fourth or last\ngeneration indicated by the cross, ranging in age from 6 to 14, are too\nyoung yet to show their condition as regards this malady.]\n\n\nThe obscure nature of recessives makes such conditions more difficult to\ndeal with than dominant defects. For as regards the latter we have seen\nthat marriage of unaffected members of the family as far as that\nparticular trait is concerned, is perfectly safe, even to a cousin, for\nonce the germ-plasm is purged of such a positive factor, it, in so far as\nwe know, remains pure. But in the case of a recessive character due to the\nabsence of some necessary determiner a normal offspring of simplex\nconstitution (Aa) will probably transmit to half of his children the\ncapacity for handing on the defect, or if mated to another normal\nindividual of simplex constitution (Aa) is likely to have the actual\ndefect revealed again in one-fourth of his children and latent in\ntwo-thirds of the remainder.\n\n=Albinism a Recessive.--=As an easily understood illustration of this type\nof case we may take human albinism, a condition which is due to the\nabsence of a pigment-developing determiner. According to Davenport the\nalbinic condition is recessive to normal condition. If albino (aa) is\nmated with albino (aa) nothing but albino children may be expected. An\nalbino (aa) mated with a normal individual will have normal offspring\n(Aa), but they will have the capacity for transmitting albinism to their\ndescendants. Thus the normal offspring (Aa) of an albino (aa) and a normal\nparent (AA) if mated to another normal individual (Aa) who has also had an\nalbino parent will probably transmit actual albinism to one-fourth of his\nchildren and the same capacity that he himself has of producing albinos,\nto one-half of his children, although the latter will appear to the eye to\nbe normal.\n\n=Other Recessive Conditions in Man.--=If for albinism we substitute\ncertain forms of insanity, hereditary feeble-mindedness (Fig. 28, p. 118),\nor hereditary epilepsy, all of which apparently follow the same law, we\ncan readily understand how unfit such matings are where both strains are\naffected. Marriage with similarly defective stock will result in the\naffection appearing in one-fourth of the progeny, and one-half of them,\nthough apparently normal themselves, will have the capacity for\ntransmitting the imperfection. It is in the existence of such hidden\nfactors that the chief danger in the marriage of cousins, or in fact any\nconsanguineous marriage lies.\n\nA few of the various defects which seem to be inherited as recessives when\nmated with normality are: susceptibility to cancer; _chorea_ (St. Vitus'\ndance); true dwarfism (all parts proportionately reduced); _Alkaptonuria_\n(urine darkens after passage); alcoholism and criminality, where based on\nmental deficiency; hereditary _hysteria_; _multiple sclerosis_ (diffuse\ndegeneration of nervous tissue); _Friedreich's disease_ (degeneration of\nupper part of the spinal cord); _Merriere's disease_ (dizziness and\nroaring in ears); _Thomsen's disease_ (lack of muscular tone); hereditary\n_ataxia_; possibly the tendency to become hard of hearing with increased\nage; and possibly, non-resistance to tuberculosis.\n\nOf non-pathological conditions in man which are inherited as recessives,\napparently either very great or very small intellectual ability are\nexamples.\n\n\n[Illustration: FIG. 28\n\nChart showing descent of feeble-mindedness as a typical recessive (after\nGoddard). Squares represent males, circles females; DD, homozygous\ndominant; DR, heterozygous dominant (i. e. normal although a carrier); RR,\npure recessive; N, normal; F, feeble-minded; A, alcoholic.]\n\n\n=Breeding Out Defects.--=Even though recessive defects occur in a stock,\nthere is the possibility of diluting out the imperfection in successive\ngenerations if care is taken always to marry into a stock wholly free from\nit. For example, a normal individual carrying a recessive defect will bear\nthe abnormality in half of his or her germ-cells. This means that when\nsuch an individual marries a normal, non-carrier, half of their children\nwill be wholly normal (AA) and half will be carriers; normal but of\nsimplex constitution (Aa). If now this generation, carriers and\nnon-carriers, marry only into normal strains of duplex constitution, then\ntheir combined issue will be likewise normal with only one-fourth of them\ncarriers of the imperfections. This means that even if all of this last\ngeneration were married to persons having the defect only one out of four\nwould have children showing it although the remaining children would be\ncarriers. On the other hand if mated to normals only one-eight of the next\ngeneration would be carriers. Thus by continually marrying into strong\nstrains liability to manifest any recessive defect can be diminished in a\nfew generations until the descendants are no more likely to have defective\nchildren than are members of our ordinary population.\n\nThe proportion in which the recessive defect would appear in successive\ngenerations if all persons in a given generation married only normal\nindividuals who were non-carriers is indicated in the following table\nwhere AA indicates a normal individual, Aa one who is normal but a\ncarrier, and aa an individual with the imperfection expressed; to indicate\nproportions simply after the first generation, four is arbitrarily chosen\nas the number of children which results from each marriage:\n\n                  Matings   Children\n  Generation 1    aa x AA = Aa\n\n  Generation 2    Aa x AA = 2AA + 2Aa\n\n  Generation 3    AA x AA = 4AA\n                  AA x AA = 4AA\n                  Aa x AA = 2AA + 2Aa\n                  Aa x AA = 2AA + 2Aa\n                           ----------\n                           12AA + 4Aa\n\n=Other Inheritable Conditions in Man.--=While many pedigrees show beyond\ndispute that such qualities as musical ability, literary ability, memory,\ncalculating ability, mechanical skill, longevity, peculiarities of\nhandwriting, obesity and muscular strength, for example, are inherited,\ntheir modes of inheritance have not yet been sufficiently analyzed to\nexpress them exactly.\n\n\n\n\nCHAPTER V\n\nARE MODIFICATIONS ACQUIRED DIRECTLY BY THE BODY INHERITED?\n\n\n=Which New Characters Are Inherited?--=Any new feature which appears in a\ngiven organism may have had its origin in some change which has come about\nin the germ from which it sprang, or it may be merely the product of some\nunusual stimulus operating on the body. While the outcome, as far as the\npresent individual is concerned, is in each case a definite modification,\nthe matter of inheritance is a very different question. On the first\nalternative where the new character is the outcome of germinal change, it\nis obvious that the altered germ-plasm will find expression in a similar\nway in succeeding generations as long as the new germinal combinations\npersist. On the other hand, if the new character has resulted merely from\nsome influence operating on the body of the individual, then to be\ninherited it would also have in some way to be transferred to and\nincorporated in the germ-plasm. Inasmuch as the body or soma of any\nindividual is highly plastic and since various of its ultimate features\nmay be mere somatic modifications, it is important to decide if possible\nwhether or not somatic variations which are not of germinal origin can be\ninherited.\n\n=Examples of Somatic Modifications.--=For example, the small foot of the\nChinese woman of certain caste is the result of inherent germinal factor\nfor the production of a foot plus the effects of binding which are in no\nwise germinal. The hand of the skilled pianist is a normal hand of\ngerminal origin and normal environment plus the effects of special\ntraining. Again, the head of the Flathead Indian is a normal head of\ngerminal origin and environment plus the effects of flattening. Similarly,\nalmost any malformation of extrinsic origin may be cited, ranging from\nmutilations and amputations, scars and the like to monstrosities such as\none-eyed fish which may be produced by subjecting a developing embryo to\nadverse conditions of development.\n\n=Use and Disuse.--=Even reactions set up through the organism's own\nactivities must produce changes. For example, a muscle has a certain\naverage of normal development in the average man; it comes to this through\nthe innate nature of its component cells plus a certain average amount of\nexercise. It may, however, be developed far beyond this average by\nexcessive exercise. On the other hand, it is a well-known fact that an\nunused organ weakens or may remain but partially developed. Thus either\nuse or disuse may play an important part in the molding of a given\nindividual. But whether or not in doing this it similarly affects the germ\nis a very different matter.\n\n=The Problem Stated.--=The question is can such enhanced or suppressed\ndevelopment, or can new or modified characters, produced in an individual\nby external agencies be so reflected on the germ-cell of the individual\nthat they tend to reappear _as such_ in its offspring without requiring\nthe same external factors for their production?\n\n=Special Conditions Prevail in Mammals.--=Before proceeding further we\nmust recognize clearly the very special conditions which exist in most\nmammals. With them environment is in part an intra-maternal environment\nand in part independent of parental influences. Thus the formula for most\nnon-mammalia would be--\n\n  Individual == egg + non-parental environment; but\n\nfor most mammals, including man--\n\n  Individual == egg + intra-maternal environment + non-parental\n  environment.\n\nThis condition in mammals introduces a complicating factor which is likely\nto obscure the whole issue unless we bear it constantly in mind. In other\nwords, we must discriminate sharply, in the discussion of inheritance in\nman, for instance, between two classes of influences which may exist in\nthe infant at birth, that is, which are _congenital_; namely, those which\nwere truly inherent--were in the germ-cells--at the very inception of the\nyoung individual, and (2) those which might later have been derived from\neither parent by the yet unborn offspring. The latter are not regarded as\ntruly hereditary. Since certain diseases or their effects belong here we\noccasionally find a physician using the term inheritance for such prenatal\ninfluences, but the more careful ones now employ the term _transmission_\nto discriminate between such conditions and true inheritance. In its\nbiological usage inheritance always refers to germinal constitution and\nnever to any condition that may be thrust on a developing organism before\nbirth. It is clear, then, that congenital conditions are not all\nnecessarily cases of inheritance.\n\n=Three Fundamental Questions.--=To get at the question of the inheritance\nof body modifications with the least confusion, let us examine it in the\nform of three fundamental questions, as follows:\n\n1. Can external influences directly affect the germ-cells?\n\n2. Can external influences, operating through the intermediation of the\nparental body, affect the germ-cells? If so, is the effect a specific and\na permanent one which persists in succeeding generations independently of\nexternal influences similar to those which originally produced it? Only\nsuch a condition as this would rank as the inheritance of a somatic\nmodification.\n\n3. Can the appearance of new characters be explained on any other ground,\nor on any more inclusive basis, than through the transmission of somatic\nacquirements, or do organisms possess heritable characters which are\ninexplicable as inheritance of such modifications?\n\nObviously the only way the question can be settled is through careful\nexperimentation in which all possible sources of error have been foreseen\nand guarded against. Much experimental work has been undertaken for the\nsolution of this problem as the goal and we may therefore select typical\nones of these experiments and apply the results toward answering our three\nquestions.\n\n=External Influences May Directly Affect the Germ-Cells.--=There is\nevidence that under special conditions external influences may in certain\norganisms affect the germ-cells, but that this occurs commonly is\nextremely doubtful. For example, Professor MacDougal, by treating the\ngerm-cells of the evening primrose with various solutions, such as sugar,\nzinc sulphate and calcium nitrate, has apparently succeeded in producing\ndefinite germinal mutations. He injected the solution into the ovary of\nthe flower the forenoon of the day at the close of which pollination would\noccur. He reports that in this way changes were produced in the germ which\nfound expression in new and permanent characters.\n\nProfessor Tower has experimented for a number of years with various\nspecies of _Leptinotarsa_, the potato beetle. By varying the conditions of\ntemperature, humidity and atmospheric pressure when females were laying\ntheir eggs, he reports having produced variations in the young which came\nfrom these eggs although the mothers themselves were not changed.\nAccording to Professor Tower slight increase or decrease in these\nenvironmental factors stimulated the activity of the color producing\nferments, giving rise to melanic or darker individuals. Greater increase\nor decrease, inhibited them and produced albinos. He found also that at\ntimes the same stimulus might show different results in different eggs.\nThe effect, therefore, is a general and not a specific one. Ordinarily the\neggs of these beetles are laid in batches. When one of these batches was\nlaid and left under normal conditions, the usual form of young hatched\nfrom it, but other batches from the same female under abnormal conditions\nresulted in the production of atypical forms. For example, a normal\ntwo-brooded form became five-brooded. The commonest modification was the\nproduction of various color types. These once established, according to\nProfessor Tower, behave as independent, inheritable units.\n\nThe experiments of Doctor Bardeen with X-rays and of others with X-rays,\nradium and other agents on the sperm and ova of amphibia show that these\nare very susceptible to injurious influence at or near the time of\nfertilization.\n\n=Such Effects Improbable in Warm-Blooded Animals.--=However possible it\nmay be to bring about germinal changes in invertebrata or lower vertebrata\nby such external agents as temperature and the like it is obvious that the\nprobability of such extrinsic influences affecting the germ-cells of\nwarm-blooded animals is very remote indeed. In the latter the germ-cells\nare more or less distant from the exterior and are at practically a\nconstant temperature. Such experiments, therefore, beyond showing the\npossibility of producing changes in germ-cells, do not have very direct\nbearing on the problem of how inheritable variations are produced in man.\nIn his case about the only avenue of approach through which germ-cells\nmight be influenced is the blood or lymph.\n\n=Poisons in the Blood May Affect the Germ-Cells.--=Any poisonous material\nin the latter might injuriously affect the gametes. We know, in fact, that\nsuch poisons as alcohol, lead and various drugs, and also the toxins of\nvarious diseases, do so affect germ-cells. It seems plausible to suppose\nthat changing conditions of nutrition may affect the constitution of the\ngerm-cells and thus induce changes in the organism which arise from these\ncells, but such nutritional effect is not yet a matter of established\nfact.\n\n=Difficulty of Explaining How Somatic Modifications Could be Registered in\nGerm-Cells.--=As to our second query concerning the possibility of\naffecting the germ-cells through the intermediation of parental tissues,\nit is evident at a glance that since the germ-cells are built up along\nwith the body and are not a product of it (Fig. 2, p. 13), if such effects\nare possible they must take place through the agency of some transporting\nmedium. The germ-cells, being lineal descendants of the original fertile\ngerm or zygote, already have the same possibilities of developing into an\nadult that the zygote had, and so the problem becomes one of modifying a\ncomplete germ already organized rather than of establishing a new germ by\ngetting together samples of every part of the body. This is all the more\nevident when one realizes that usually the germ-cells are set apart long\nbefore the body becomes adult, that is, before the body has developed most\nof its characteristics. Moreover, among lower animals many instances are\nknown where the immature young or even larvae will produce offspring which\nnevertheless ultimately manifest all the structures of the adult\ncondition.\n\nBut supposing specific modifications of the germinal mechanism were\npossible, it is difficult to comprehend how an influence at a distant\npoint of the body could reach the germ-cell, to say nothing of the even\ngreater difficulty of understanding how it could become registered in the\ngerm in a specific way as affecting a particular part. For it must be\nremembered that the organs of the adult do not exist as such in the germ\nbut are present there only as potentialities. How, for example, can a\nchange in the biceps muscle of one's arm be registered in a germ-cell in\nwhich there is no biceps muscle, but merely the possibilities of\ndeveloping one? Or how can increased mental ability which is contingent on\nthe elaboration of certain brain-cells be impressed on a germ which has no\nbrain-cells but only the capacity under certain conditions of producing\nsuch cells? For the brain of a child is not descended from the brain of\nhis parent, but from a germ-cell carried by that parent.\n\n=Persistence of Mendelian Factors Argues Against Such a Mode of\nInheritance.--=On the face of things, the apparent inviolability of\nMendelian factors which may remain unexpressed in the germ for one or many\ngenerations--indeed the whole matter of genotypical differences in the\ngametes of the same individual--shows the improbability of somatic\ninterference with the germ-plasm. But notwithstanding this, because of the\ngreat importance of the issue, it is well to review in some considerable\ndetail the various phases and possibilities of the question.\n\n=Experiments on Insects.--=Some of the attempts to secure evidence of the\ntransmission of personally acquired parental modifications in insects are\nvery interesting. Many insects in the larval stages, particularly just\nafter pupation seem to be especially susceptible to external influences.\nThey have been much used, therefore, for purposes of experiment. It has\nlong been known that differences in size, in color and even in the shape\nof wings can be produced by various agents if applied at this period of\ndevelopment. From the standpoint of heredity, however, the important\nconsideration is to determine if these experimentally induced changes have\nbeen reflected on to the germ-cells so that they reappear in the offspring\nof the modified individuals.\n\nIt has been found that in some cases where male and female are of\ndifferent color, the color of the female can be changed to that of the\nmale by altering the conditions of temperature. In certain cases types can\nbe changed by cold so that they resemble varieties of the same species\nfound farther north, and by heat, varieties found farther south. But not\nall individuals of a given lot are affected, and often different\nindividuals of the same kind show different effects. Moreover, in some\ncases the same aberrations were produced by heat as by cold. This\nindicates that it is not so much a question of specific effects as a\ngeneral physiological change, apparently mainly a matter of direct\ninfluence of temperature on the chemical composition of the pigments. The\nCountess von Linden in fact has shown that the extracted pigments can be\nmade to undergo the same changes of color in a test-tube by heat and cold\nas in the pupae. But there is no evidence that the germ-cells of the living\ninsect were affected in a specific way. In a small fraction of the\noffspring of such modified individuals abnormalities appeared, but these\nwere not always of the same kind as those which had been produced in the\nparent. That is, there was no evidence of a trait or character having been\nacquired by the body and handed on to the germ-cell. Where an effect was\nproduced on the germ-cell it was probably produced directly as in the\nfirst cases discussed.\n\nSize, colors and markings of butterflies have also been altered by\nsubjecting the caterpillars or the pupae to such influences as strong\nlight, electricity, various chemical substances, centrifuging, diminished\noxygen supply, etc., but the results were in the main confined to the\nimmediate generations. In the few cases where permanent inheritable\nchanges were seemingly produced they were more reasonably interpreted as\nthe effects of direct action on the germ-cells than as examples of\ninherited somatic modifications.\n\nStarvation experiments which resulted in the dwarfing of adult individuals\nhave been performed on various insects, and while the dwarf condition may\npersist through one or two generations due to a diminished food supply in\nthe eggs of the dwarf, the stock in question when returned to normal food\nconditions soon resumes its original characteristic size.\n\n=Experiments on Plants.--=Many experiments have been performed with\nplants, inasmuch as they are particularly prone to become modified by\nchanges of food supply, or climate. For example, plants which grow\nluxuriantly in a warm moist climate or a rich soil may become stunted and\nmarkedly changed if transplanted to a cold climate or a poor soil.\nNaturally, their progeny will exhibit the same behavior as long as they\nare kept under the new conditions. Experiments carried on through numerous\ngenerations, however, practically all show that the germinal constitution\nof the plants remains unchanged, for when their seeds are planted under\nthe original favorable conditions of soil or climate, the plants resume\ntheir former habits of growth. Naegeli, for instance, who made a study of\nmany varieties of Alpine plants, and who carried on experiments with many\nof them for years in the Garden of Munich, concluded that no permanent\neffects had been produced by the Alpine climate and conditions in plants\nfrom other regions which had come under its influence. A few botanists\nhave claimed to have found that the changes produced by the Alpine climate\nhave persisted for a generation or two and have then worn off. More recent\nexperiments on various of our field grains which have been stunted and cut\ndown in productivity by growing for a number of generations under adverse\nconditions show that they have not been permanently modified by such\ntreatment, for they resume normal productivity and size when grown again\nunder favorable conditions.\n\nOn the other hand, Lederbaur found that a common weed, _Capsella_, when\ntransplanted from an Alpine habitat to the lowlands did not return to the\nlowland type of the weed, but retained certain of its Alpine\ncharacteristics. It is not clear, however, that this particular species\nduring its long sojourn of many generations in Alpine conditions may not\nhave undergone a series of germinal variations and have developed into a\nnew variety or species quite independently of changes wrought in the germ\nby reflected somatic effects. Indeed, in face of the preponderance of\nother cases to the contrary, this interpretation would seem to be the more\nplausible one.\n\n=Experiments on Vertebrates.--=In the vertebrates we may also find\nexamples of various somatic modifications experimentally produced, but\nevidence of their inheritance is as difficult to establish as in the\ninvertebrates. Let us examine a few of the more significant of these which\nare alleged by some to bear evidence of such inheritance.\n\nBy decreasing the amount of water in an aquarium Marie von Chauvin was\nable to transform the aquatic, gill-breathing salamander _Axolotl_ into\nthe gill-less land form _Ambystoma_, heretofore regarded by systematists\nas a different species. Either of these forms when sexually mature\nproduces its like. The salamanders in question have both lungs and gills,\nbut after a time the ones which are to be land forms lose their gills and\nbecome exclusively lung-breathers. What seems to have been accomplished\nthen is the accelerating or forcing of normal natural tendencies already\ninherent in the organism instead of introducing something new into the\ninheritance by way of the soma. _Axolotl_ is in all probability merely a\nlarval form of _Ambystoma_ which with high temperature and an abundance of\nwater reproduces without advancing to the final possible stage of its life\ncycle.\n\n=Epilepsy in Guinea-Pigs.--=Perhaps the most frequently cited case and the\none in which the defenders of the idea of somatic inheritance usually take\nfinal refuge is that of Doctor Brown-Sequard's guinea-pigs,\nnotwithstanding the fact that no one has had convincing success in\nrepeating the experiments and that the original results are apparently\nopen to more than one interpretation. This experimenter rendered\nguinea-pigs epileptic by certain injuries to the nervous system. Epilepsy\nappeared in some of the offspring of these operated animals. He regarded\nthis as an example of the inheritance of an artificially induced epilepsy.\nAn indirect loss of toes occurred in some of the parents as a result of\nthe operations on the nervous system. Some of their young also had missing\ntoes. However, as has been pointed out by various critics, guinea-pigs are\nstrongly predisposed toward epileptic-like seizures, and the epilepsy in\nthe young may have been merely a coincidence. Voison and Peron believe\nthey have shown that in epilepsy a toxin is produced that may affect the\nunborn fetus. That is, the result might have been due to a poison derived\ndirectly from the mother. The experiments in fact show that it was mainly\nin the offspring of affected mothers that the condition appeared. Others\nmaintain that we do not know the exact nature of epilepsy, that in some\ncases it may be the result of infection by disease-germs, and that\nBrown-Sequard's cases may, therefore, have been merely the communication\nof a disease from parent to child. As to the disappearance of toes it is a\nwell-known fact that rodents in particular are likely to gnaw off the toes\nof their young very soon after birth, and little credence can be put in a\nlack of toes in such young as cases of inheritance except under conditions\nof much more careful observation than existed in Brown-Sequard's\nexperiments. A fuller account of these experiments will be found in\nRomanes' _Darwin and After Darwin_, Vol. II, Chap. 6.\n\n=Effects of Mutilations Not Inherited.--=Many experiments have been\nperformed by investigators to determine whether or not the results of\nmutilation are transferred to succeeding generations, but so far only with\nnegative results. Many such experiments have been unwittingly carried on\nfor many generations, in fact, by breeders and fanciers, in the docking of\nhorses, dogs and sheep, the dehorning of cattle and the like, yet no\nsatisfactory evidence of the transmission of such conditions in any degree\nhas ever been forthcoming. The mutilations or distortions of the human\nbody through various rites or social customs also fails to yield any\nconvincing examples. Foot-binding, head-binding, or waist-binding must be\nrepeated in each successive generation to produce the particular type of\n\"beauty\" that results from such deformities. And lucky it is for man that\ninjuries do not persist in subsequent generations, otherwise the modern\nhuman being would be but a maimed relic of past misfortunes.\n\n=Transplantation of Gonads.--=An interesting experimental test regarding\nthe effect of the body on the germ was made recently by Castle and\nPhillips with guinea-pigs. It will be recalled from the discussion on\nMendelism that when a black guinea-pig is mated with a white one the\noffspring are always black. These experimenters transplanted the ovaries\nfrom a young black guinea-pig to a young white female whose own ovaries\nhad been previously removed. This white female was later mated to a white\nmale. Although she produced three different litters of young, six\nindividuals in all, the latter were all black. That is, not a trace of\ncoat-color of the white father or of the white foster-mother was impressed\non the transplanted germ-cells or the developing young. Later experiments\nof the same kind by Castle and Phillips, with other varieties of\nguinea-pigs, have yielded the same results. The body of the mother,\nindeed, seems to serve merely as a protective envelope and a source of\nnutrition.\n\n=Effects of Body on Germ-Cells General, Not Specific.--=As far as the\nevidence regarding the modification of the germ-plasm by the body is\nconcerned, we must conclude then that while under special circumstances\nthe germ-cells may be affected, the effect is general rather than specific\nand the result as seen in the offspring has no discoverable correlation\nwith any particular part or structure of the parental soma. The effect is\npresumably of much the same nature as where the germ is directly affected\nby external agents. Where a new character or a modification of one already\nexisting is produced by a given condition of environment, in our\nexperience so far to have the same repeated in the offspring, a similar\nevocative condition must prevail in the environment of the latter. Or in\nother words the new character is not a permanent one which persists in\nsucceeding generations independently of external influences similar to\nthose which originally produced it.\n\n=Certain Characters Inexplicable as Inherited Somatic Acquirements.--=It\nwould require remarkable credulity, in fact, to believe that some of the\nmost striking features about certain plants or animals could have been\ndeveloped by means of the inheritance of somatic modifications. For\nexample, many animals such as the quail, the rabbit, or the leaf-butterfly\nare protectively colored. That is, they harmonize in color-pattern with\ntheir surroundings so closely that they are overlooked by their enemies.\nBut how can this oversight on the part of an enemy so affect the bodies\nand through them the germ-cells of such individuals as to develop so high\na degree of protective coloration? Or how, indeed, could any of numerous\nadaptive structures which one can think of, such as the color or scent of\nflowers to lure insects for cross-pollenation, the various grappling\ndevices on many seeds to secure wide distribution by animals, or the like,\nhave been directly produced by use or disuse or by any variation produced\nin them by the agents to which they are adapted?\n\n=The Case of Neuter Insects.--=A very instructive example of the\nimprobability that great skill, highly specialized structures, or certain\ninstincts are first developed in the parental body as the result of use\nand then passed on to the offspring, is seen in the case of neuter\ninsects. In bees, for example, there are three classes of individuals: the\ndrones or males; the queens or functional females; and the workers, which\nare neuter, that is, take no part in reproduction. The latter are really\nsexually undeveloped females. The queen can lay either fertilized or\nunfertilized eggs. The latter always give rise to males. The workers\ngather the food, attend the queen, wait on the young, construct the comb,\nand in short perform all the ordinary functions of the colony except the\nreproductive. They have many highly specialized structures on various\nparts of their bodies for carrying on their many activities, as well as\nthe very highly specialized instincts necessary to the maintenance of the\ncolony. But now, complex and highly developed as these workers are, since\nthey do not give rise to offspring, no matter how much experience or\nstructural modifications they may acquire during their lifetime, it can\nnot be handed on to another generation. Nor can they have come to their\npresent highly organized state through such a form of transmission since\nthey are not the descendants of workers but of a queen. Any new\nmodifications that appear in the workers of a colony must therefore have\ntheir origin in changes which have taken place in the germ-cells of the\nqueen, and not in the soma of some other worker. It has been argued that\nthe worker has not always been infertile; that at a more primitive stage\nof the evolution of the bee colony every female was both worker and\nmother, and that individual somatic acquirements might therefore have been\ntransmitted, but this argument can not hold for many of the instincts or\nfeatures of the modern bee because these have to do only with the\nconditions of life which exist in the colony in its present form. It is\nobviously absurd to maintain, for instance, that all the highly\nspecialized instincts incident to queen production, queen attendance and\nthe like were functionally produced through usage before there was any\nqueen to produce or attend, while on the other hand, the very necessity of\nqueen production and maintenance is the outcome of the infertility of the\nworkers. Some workers have been known to lay eggs, but as these are few in\nnumber and are never fertilized, which means if they develop they can only\nproduce males, they can play no considerable part in inheritance.\n\n\nORIGIN OF NEW CHARACTERS\n\n=Origin of New Characters in Germinal Variation.--=This brings us to our\nlast query as to whether the appearance of new characters can be explained\non any other or any more inclusive ground than that which infers that\nchanges undergone by the parent-body are in some way registered in the\ngerm-cells so as to be repeated in a certain measure in the body of the\noffspring. The answer to the question of how inheritable variations do\ncome to appear in offspring if not through changes produced in the body of\nthe parent, is uncertain; nevertheless most biologists believe that they\ndo not have such a somatic origin but arise directly as germinal\nvariations. Some would attribute them to the fluctuating nature of living\nsubstance in general. The instability of protoplasm is one of its striking\ncharacteristics. It is constantly being broken down and built up, or, in\nother words, undergoing waste and repair. Like all other protoplasm, that\nof the germ-cells must also undergo these metabolic changes and it is\npossible though not proved that in this give and take of substances small\nchanges occur in their constitution which find expression in the offspring\nas variations. As already seen, substances in the blood other than food\nmay also affect the constitution of the germ-cells.\n\n=Sexual Reproduction in Relation to New Characters.--=Some biologists\nattribute great importance to sexual reproduction as a basis of variation\nand the origin of new characters. They argue that the mingling of\ndeterminers from two different lines must produce many new combinations\nand expressions of germinal potentialities. Plausible as the argument\nseems at first sight no one has succeeded as yet in securing proof that\nabsolutely new characters can be originated in this way. What seems to\noccur under such circumstances is merely a reshuffling or sorting of old\nunit-characters. Although innumerable permutations and combinations of\nthese may be made which find new expression outwardly, this is obviously\nnot creating determiners of new unit-characters in the germ-plasm. While\nmany biologists would not deny the possibility or even the probability\nthat the determiners of unit-characters may sometimes combine or influence\none another so as to form actual permanent new characters, the proof of\nsuch performance is wholly lacking. On the other hand, there are not a few\nbiologists who argue that sexual reproduction accomplishes just the\nreverse of increasing the extent of variation or creating new characters;\naccording to them it tends to annul exceptional peculiarities of either\nparent by throwing the offspring back to the average racial type. It is\nthus looked on by these advocates as a stabilizer which reduces the\namplitude of variations instead of increasing them. As a matter of fact\nthe two ideas are not mutually exclusive; sexual reproduction may\naccomplish both of these ends. A limited number of observations and\nexperiments have been made to test out the correlation between sexual\nreproduction and variation, but they have so far been too few or too\ninconclusive to enable us to come to a satisfactory conclusion.\n\nWhile we are uncertain about the method of origin of new characters the\nfact remains that they do arise in abundance as abrupt mutations or\notherwise and become a part of the permanent heritage of a stock. It is\nclear that sexual reproduction may be one important means by which a given\nnew character which has arisen in one or a few individuals may become\nincorporated in the species at large. Through Mendelian combinations and\nsegregations it would by cross-breeding be spread and gradually introduced\ninto more and more strains of the general population.\n\n=Why So Many Features of an Organism Are Characterized by\nUtility.--=Germinal variations are seemingly at first more or less hit or\nmiss affairs as far as utility to the organism is concerned. Useless\nvariations, so long as they are not actually harmful, may persist and\napparently be indefinitely inherited. However, a special premium is put on\nvariations which happen to be useful for they help the organism to succeed\nin its struggle for life and since success in the world of life means not\nonly mere individual survival but also the production of progeny, through\nthis very means insured transmission to subsequent generations. It is\nprobable that the very many useful features of any organism, that is, its\n_adaptations_, have thus been established. It is possible also that many\nvariations which at their inception are indifferent may wax in strength in\nsuccessive generations until they reach a point where they must become\neither useful or harmful. In the former case they would mean increased\ninsurance of survival for their possessors, in the latter, elimination.\nWith such an automatic process as this operative in nature it is not\nastonishing that the main features of any organism are characterized by\ntheir utility to it.\n\n=Germinal Variation a Simpler and More Inclusive Explanation.--=The gist\nof the whole matter regarding the source of new characters in offspring\nseems to be that the explanation based on the idea of germinal variation\nis in last analysis the simpler and more inclusive, and there is no\nalleged case of inheritance of parental modification, which can not be\nequally well explained as the result of a germinal variation. There are\nnumerous cases which can not be explained as transmissions of somatic\nacquirements even if this transmission could be established in certain\ncases. So, many biologists argue, why have two explanations when one is\nsufficient, especially when the other has never been conclusively\nestablished as true in any case and is obviously untrue in certain test\ncases? The attitude of most investigators is that of the open mind. While\nfeeling that the weight of probability is very decidedly against the\ntheory of the inheritance of somatic modifications, they still stand ready\nand willing to accept any evidence in its favor which when weighed in the\nbalance is not found wanting.\n\n\nANALYSIS OF CASES\n\nWhile space will not permit extended discussion, in order further to fix\nthe nature of the problem in mind as well as to exemplify the conditions\nthat must be satisfied to form convincing evidence of inherited somatic\nacquirements, it will be well perhaps to analyze a few typical cases as\nthey are frequently cited.\n\n=Are the Effects of Training Inherited?--=Breeders and trainers very\ncommonly believe that the offspring of trained animals inherit in some\nmeasure the effects of the training. Thus the increased speed of the\nAmerican trotting horse is often pointed to as strong evidence of such\ntransmission. According to W. H. Brewer, the earliest authentic record of\na mile in three minutes was made in 1818. The improvement, approximately\nby decades, from that time was as follows:\n\n  During 1st decade after 1818, improved to 2:34\n         2nd   \"      \"    \"       \"     \"  2:31-1/2\n         3rd   \"      \"    \"       \"     \"  2:29-1/2\n         4th   \"      \"    \"       \"     \"  2:24-1/2\n         5th   \"      \"    \"       \"     \"  2:17-1/2\n         6th   \"      \"    \"       \"     \"  2:13-1/2\n         7th   \"      \"    \"       \"     \"  2:08-1/2\n\nBy 1892, the date of Professor Brewer's publications (See _Agricultural\nScience_, Vol. 4, 1892) the record had reached 2:08-1/2. Since then it has\nbeen lowered still further.\n\nOn the face of it this looks like a good case of inheritance of training,\nand Brewer himself believed it such. If so this would mean that colts of a\nhighly trained trotter would be faster than they would have been if their\nparent had remained untrained. It is impossible to get positive proof in\nthe case of any trained horse since there is no way of establishing just\nhow speedy the progeny would have been had the parent remained untrained.\nIf it could be shown that colts sired by a trotter late in life were on\nthe whole faster than those sired by the same father when younger and as\nyet not highly exercised in trotting, then the facts might give some\nevidence of value, but unfortunately no such records are available.\n\nOn the other hand, even ignoring the fact that improvement in track and\nsulky are probably the biggest items in the shortening of records in\nrecent times, _selection_ instead of inheritance of the effects of\ntraining will equally well account for any innate progress in trotting.\nAnd since, as pointed out by Professor Ritter, there are even more\nstriking cases of similar improvements in other fields, such as college\nathletics, where the factor of use-inheritance is entirely precluded, it\nis wholly unnecessary to postulate it in the case of the trotter.\n\nFor example an inspection of the records of college athletics for the last\nthirty-five years in running, hurdling, pole-vaulting, jumping, putting\nthe shot, etc., shows on the whole a steady advance year by year.\nMoreover, the greatest improvement has occurred in those events in which\nskill and practise count for most together with selection of the\ninherently ablest candidate for the events. But in the case of athletics\nthe improvements shown in thirty-five years have all come within a single\ngeneration and hence the inheritance of the effects of training is ruled\nout as a factor. Selection and improved training are the only factors\noperative.\n\nIn the case of the trotter inheritance undoubtedly has also been a factor,\nbut inheritance based on selection of what the race-track has shown to be\nthe speediest individual, not inheritance of the effects of training. In\nother words, horses which have shown the capacity for being trained to the\nhighest degree of speed have naturally been selected as sires and dams\nand so through selection generation after generation a speedier strain has\ngradually been established.\n\n=Instincts.--=When we turn to the realm of mental traits, particularly of\ninstincts, we meet with a whole host of activities which are frequently\npointed to by transmissionists as examples of inherited acquirements. Thus\naccording to them, habits at first acquired through special effort\nultimately become instinctive, or according to some, instinct is \"lapsed\nintelligence.\" Instances often cited are the pointing of the bird-dog, the\nextraordinary crop-inflation of the pouter-pigeon, or the tumbling of the\ntumbler pigeon. We can not stop to discuss these cases beyond pointing out\nas many others have done that practically all dogs have more or less of an\nimpulse to halt suddenly, crouch slightly and lift up one fore-foot when\nthey scent danger or prey, that all pigeons pout more or less, and that\npractically all show more or less instincts of tumbling when pursued by a\nhawk. Thus in all of these cases the fundamental germinal tendency is\nalready at hand for the fancier to base his choice on and thus through\nselection build up the type desired. Just as in the fan-tailed pigeon, by\nrepeatedly selecting for breeding purposes individuals which showed an\nunusual number of tail-feathers he has built up a type with an upright,\nfan-like tail having many more feathers than the twelve found in the tail\nof the ordinary pigeon, so by similar procedure in the case of other forms\nhe has markedly enhanced certain features. The idea of instincts being\n\"lapsed intelligence\" is so clearly and concisely criticized in an\narticle by the late Professor Whitman[4] that I can not do better than\nquote an excerpt. His views to the contrary are as follows:\n\n    \"The view here taken places the primary roots of instinct in the\n    constitutional activities of protoplasm and regards instinct in every\n    stage of its evolution as action depending essentially upon\n    organization. It places instinct before intelligence in order of\n    development, and is thus in accord with the broad facts of the present\n    distribution and relations of instinct and intelligence, instinct\n    becoming more general as we descend the scale, while intelligence\n    emerges to view more and more as we ascend to the higher orders of\n    animal life. It relieves us of the great inconsistencies involved in\n    the theory of instinct as \"lapsed intelligence.\" Instincts are\n    universal among animals, and that can not be said of intelligence. It\n    ill accords with any theory of evolution, or with known facts, to make\n    instinct depend upon intelligence for its origin; for if that were so,\n    we should expect to find the lowest animals free from instinct and\n    possessed of pure intelligence. In the higher forms we should expect\n    to see intelligence lapsing more and more into pure instinct. As a\n    matter of fact, we see nothing of the kind. The lowest forms act by\n    instinct so exclusively that we fail to get decided evidence of\n    intelligence. In higher forms not a single case of intelligence\n    lapsing into instinct is known. In forms that give indubitable\n    evidence of intelligence we do not see conscious reflection\n    crystallizing into instinct, but we do find instinct coming more and\n    more under the sway of intelligence. In the human race instinctive\n    actions characterize the life of the savage, while they fall more and\n    more into the background in the more intellectual races.\"\n\nFor further discussion of this field the reader is referred to an\nexcellent chapter on \"Are Acquired Habits Inherited?\" in C. Lloyd Morgan's\nbook, _Habit and Instinct_.\n\n=Disease.--=Perhaps in the realm of disease more than in any other has an\ninterest in the inheritance of somatic acquirements been manifested. The\nproblem arising here is not essentially different from other questions of\ninheritance but since it is a matter of such practical importance to man,\nwe may well give it special attention. We have to deal simply with the old\nquestions of what is constitutionally in the germ, what is acquired by the\nbody, and lastly, whether the somatically acquired is inherited. While we\nall know in a general way what is meant by disease, especially if some\nspecific disorder such as scarlet fever, malaria or tuberculosis is\nmentioned, an attempt to give an accurate definition is much like trying\nto define a weed, inasmuch as what is functionally all right at one time\nor place may be all wrong at another, or what is normal in one animal may\nbe abnormal in another. In general we may say that disease is derangement\nor failure of physiological function.\n\n=Reappearance of a Disorder in Successive Generations Not Necessarily\nInheritance.--=In attempting to study the inheritance of diseases we must\nrecognize clearly at the outset that reappearance of a disease in\nsuccessive generations by no means necessarily signifies inheritance.\nBefore it can be pronounced such we must make sure that it is not a case\nof reimpressing similar modifications on the individuals of successive\ngenerations. For example, in England there is a well-recognized condition\nknown as collier's lung which results from constant working in coal mines.\nAnd while both father and son may exhibit it, because of their similar\noccupations, there is nothing hereditary about the malady. Likewise there\nis what is known as emery grinder's lung, and practically every large\nmanufacturing city with soot-laden atmosphere leaves its impress on the\nlungs of the inhabitants. This will occur, of course, generation after\ngeneration, as long as such pollutions of the atmosphere continue to\nexist. It is clear that any unhealthy occupation is likely to cause the\nreappearance of an associated typical disease generation after generation\nas long as the children follow the calling of their parents. The common\nmisconception that deformities or postures associated with a trade, such\nas a shoemaker's or tailor's, is genetically stamped on offspring by the\nend of the third or fourth generation results from failure to discriminate\nbetween real inheritance and mere reappearances under similar conditions\nof environment.\n\n=Prenatal Infection Not Inheritance.--=Again, we must recognize that\nprenatal infection is not inheritance. We have already seen that the young\nmammal undergoes a certain period of intra-maternal development, but\ninfluences operating on it during this period of gestation must be\nreckoned with as environmental, not germinal. For example, it is said that\nan unborn child may take smallpox from its mother but this and all similar\noccurrences are cases of contagion. We find the great pathologist,\nVirchow, who with many others of his time was a believer in the\ninheritance of acquired characters, saying nevertheless regarding such\ninstances that, \"What operates on the germ after the fusion of the\nsex-nuclei, modifying the embryo, or even inducing an actual deviation in\nthe development, can not be spoken of as inherited. It belongs to the\ncategory of early acquired deviations which are therefore frequently\ncongenital.\"\n\n=Inheritance of a Predisposition Not Inheritance of a Disease.--=We must\ndiscriminate sharply also between the inheritance of a predisposition and\nthe inheritance of a disease itself.\n\nWe often hear the statement made that tuberculosis is inherited and have\ncited in evidence certain consumptive families or strains. But\ntuberculosis is a bacterial disease and children of tuberculous parents\nare never born with the disease except in the rarest of instances.\n\n=Tuberculosis.--=What is really inherited is a constitutional\nsusceptibility to this particular germ. While almost any individual may\ncontract tuberculosis when in a state of depressed vitality, or under\nstress of adverse surroundings, there is no doubt that certain families\nare more easily infected than others and much less resistant to the\nravages of the disease when once it gains a foothold. However, a\npredisposition is a vastly different thing from the inheritance of the\nactual disease. For just as we are born with a nose well adapted to\neye-glasses but not with eye-glasses on our nose, so many of us are born\ntuberculizable though not tuberculous, and every sanitary advance we make\ntoward lessening the chances of infection is just so much more insurance\nfor the susceptible.\n\nThe whole problem of tuberculosis is an extremely complex one. We do not\nknow just the measure of the inheritance of the predisposition. Some\nwriters in the past have maintained that tuberculosis is mainly a question\nof infection and not of inherent susceptibility, but steadily increasing\nevidence all points the other way.\n\nWhere the predisposition exists the chances of infection are still, even\nunder the conditions of present-day sanitation, very great. The close\nassociation between a consumptive and other members of the family through\na prolonged period of time, of course, renders the latter likely to\ninfection unless unusual care is exercised. Very often where a parent is\nconsumptive a child contracts the malady shortly after birth and is\nparticularly likely to do so if the mother, who nurses it and cares for it\nmost intimately, is the tubercular member of the family. Where the mother\nis tubercular, indeed, the probabilities are that the child has already\nbefore birth had its vitality lowered through the toxins circulating in\nher blood or through defective nutrition, and in consequence does not\nresist well any diseases.\n\nUndoubtedly a large proportion of our infant mortality is of tubercular\norigin. It is now a well-established fact that much tuberculosis in\nchildren is attributable to drinking milk from tuberculous cows, yet we\nfind individuals so uninformed and dairymen so mercenary that they fight\nall attempts of the commonwealth to test out cattle for tuberculosis so as\nto condemn the infected individuals and thus save our babies. Recent\ninvestigations made in some of our large pork-packing establishments also\nindicate that hogs, especially such as have been around tubercular\ncattle, are often shot through and through with tuberculosis and that such\nflesh when used as food, if not thoroughly cooked, may become a serious\nmenace to our health.\n\nWith the wide prevalence of bovine and human tuberculosis it is little\nwonder that nearly every human being becomes more or less infected at some\nperiod of life. Autopsies on large numbers of individuals in some of our\ngreat hospitals have shown that as many as ninety-nine per cent. of the\nsubjects show tubercular lesions of some kind. While it is true that the\nclass of people who would come to autopsy in such public hospitals would\nperhaps be more likely to be tubercular than the average of the community,\nstill it can not be denied that a very large degree of infection exists.\nPearson, from statistics gathered in Europe, has shown that about eighty\nto ninety per cent. of the population have tubercular lesions before the\nage of eighteen. Hamburger found that in Vienna ninety-five per cent. of\nthe children of the poor, between twelve and thirteen years of age, were\ninfected with tubercular bacilli and he estimates that all would be before\nmaturity. According to Doctor Mott, pathologist to the London County\nAsylums, the insane between the ages of fifteen and thirty-five are about\nfifteen times as likely to acquire tuberculosis as the sane are.\n\nYet the mortality from tuberculosis, great though it be, is obviously not\nin proportion to the enormous degree of infection. The crux of the\nsituation is mainly the matter of resistance. From the standpoint of\nheredity, therefore, the question largely resolves itself into one of the\ninheritance or non-inheritance of constitutional resistance. Some are\npredisposed to be non-resistant and hence succumb.\n\nThe work of Karl Pearson[5] and other recent researches forcibly indicate\nthat hereditary constitutional predisposition is one of the chief factors\nconcerned in subjects who develop well defined attacks of the disease. Yet\nwe must not forget that there are degrees of susceptibility and that\ntherefore a constitutional predisposition which might be of little\nsignificance under good average conditions of nutrition and sanitation\nmight be insufficient under unfavorable conditions.\n\nBefore we can make any relatively accurate estimate of the exact degree to\nwhich the malady is based on inheritance we must have more data. Many\ndifficulties beset the path of the investigator. In the first place, when\none gets back a generation or two he finds that diagnosis was crude and\nuncertain; a given malady may or may not have been tuberculosis. The main\nerror however was probably on the side of not recognizing it in mild or\nobscure cases. Then again the questions of virulence of the infection, of\nsize and frequency of the dose, etc., are also complicating factors.\nMoreover, in very many cases the infection is a mixed one and hence we are\ndealing with other factors than straight tuberculosis.\n\n=Two Individuals of Tubercular Stocks Should Not Marry.--=However,\nsufficient is now known of the inheritance of susceptibility to the\ndisease that we can have little conscience toward the welfare of the race\nif we in any way countenance the marriage of two individuals who come each\nof tubercular strains, and marriage of even a normal person into a badly\ntainted strain, where the one married is tubercular, is extremely\nhazardous looked at from the standpoint of the children likely to be born\nof such a union. The Supreme Court of New York recently held that the\nfraudulent concealment of tuberculosis by a person entering into a\nmarriage relation is ground for the annulment of the marriage.\n\n=Special Susceptibility Less of a Factor in Many Diseases.--=With some\ndiseases such as leprosy, typhoid fever, smallpox and cholera there seems\nto be less a question of special susceptibility since nearly all persons\nare vulnerable. Yet in cases of typhoid, at least, there are some\nindications that certain families are more likely to take the disease than\nothers under similar exposure. We know of no inherited effects of such\ndiseases, however. For instance, children of lepers do not inherit leprosy\nand if kept out of leper districts remain normal.\n\n=Deaf-Mutism.--=In certain abnormal states there is danger of confusing\nsimilar conditions which may have two entirely different sources of\norigin. Deafness, for example, may be strictly inborn as the outcome of a\ngerminal variation or it may result from extraneous influences such as\naccidents, infective diseases, neglected tonsils and the like. The former\nis inheritable, the latter not. Bell in 1906 in a special census report to\nthe United States government showed that deaf-mutism is markedly\nhereditary, particularly where deaf-mutes intermarry as they are prone to\ndo. Fay's extensive studies on _Marriage of the Deaf in America_ also\ndemonstrate the hereditary nature of the congenital forms of deafness. Cut\noff as such individuals are from communication with normal people, the\nassociation of the two sexes in special schools and institutions is of\ncourse highly conducive to such marriages. The defect seems to behave in\nthe manner of a Mendelian recessive. Two deaf-mutes should not have\nchildren and yet such marriages are occurring every day. Even if two\npersons marry from families which tend to become hard of hearing the\nevidence indicates that their children are likely also to develop this\npartial deafness as they grow older, although it seems safe for a person\nof such tendency to marry into a family without it.\n\n=Gout.--=In such disorders as gout there is little question but that a\ntendency to it runs in families. On the other hand it may also be acquired\nwithout special susceptibility. There is no evidence, however, that\nbecause a father has gout the effect of the gout is reflected on his\ngerm-cells and the son has gout as a result. Indeed, often a son who\nbecomes gouty was born long before the father became gouty. Son and father\nboth have gout then, because each has innate germinal tendencies which\nwhen subjected to certain evocative stimuli become expressed as gout.\n\n=Nervous and Mental Diseases.--=Inasmuch as the question of nervous and\nmental diseases has become one of such overshadowing importance at the\npresent day, a discussion of the subject at some length will be presented\nin a separate chapter. I shall merely point out here that the general\nverdict of experts in nervous and mental disorders is to the effect that\nexternally induced mental disorders are of rare occurrence except as the\nresult of general poisoning or enfeeblement of the system in some way, or\nby traumatic conditions such as a blow on the head, and that there is no\nevidence of the transmission of the effects of such conditions. In most\ncases of insanity, supposedly caused by fright or worry, a close study of\nthe family stock will reveal nervous instability of some kind. The\nsupposed cause has been merely the precipitating stimulus which has\nbrought to expression a dormant weakness of germinal origin. The stress\nand strain of modern life is particularly likely to test out and reveal\nsuch neurally unstable individuals.\n\n=Other Disorders Which Have Hereditary Aspects.--=Space will not permit\ndiscussion of various other specific disorders which are known to have\nimportant hereditary aspects, although none shows any convincing evidence\nof having become hereditary in nature through first affecting the soma.\nSome of these, such as epilepsy and other nervous affections,\ntuberculosis, color-blindness, cataract and various malformations, have\nalready been mentioned. Others that may be listed are cancer,\narterio-sclerosis, obesity and certain forms of rheumatism, and of heart\nand kidney diseases. In practically all of these cases in which heredity\nenters as a factor the condition is one of inheriting a special\nsusceptibility and not the disease itself. Which means simply that the\ndisorder in question is much more easily called forth in such persons by\nappropriate bacterial or other stimulus, than in the case of the normal\nindividual.\n\n=Induced Immunity Not Inherited.--=Lastly, it is well known that various\nanimals, including man, after recovery from an attack of any one of\ncertain diseases, become more or less immune from further attacks of the\nsame disease. Moreover in some instances as in inoculation against typhoid\nor diphtheria, immunity may be artificially induced by means of\nanti-toxins. The question arises as to whether such immunity is\ntransmitted to offspring. Experiments have been made (see _Bulletin No.\n30, U. S. Hygienic Laboratory_) to test this and it has been found that\nthe condition is not inherited. Young guinea-pigs, for instance, born of\nmothers immunized during pregnancy are immune at birth but they lose their\nimmunity in the course of a few weeks. The effect is clearly one of direct\ntransference from the blood of the mother. The same temporary immunity can\nbe produced in the young, in fact, by merely having them nurse from an\nimmunized mother.\n\n=Non-Inheritance of Parental Modifications Has Social, Ethical and\nEducational Significance.--=Like many other biological conclusions these\nrelative to the non-inheritance of parental modifications are of extreme\nimportance to humanity. It is clear that they have not only physical but\nsocial, ethical and educational significance. For if the education which\nwe give our children of to-day, or the desirable moral conduct which we\ninculcate does not affect the offspring of succeeding generations through\ninheritance, then the actual progress of the race is much slower than is\ncommonly supposed, and the advance of modern over ancient times lies more\nin an improvement in extraneous conditions through invention and the\naccumulation and rendering accessible of knowledge, than in an actual\ninnate individual superiority. And when we face the issue squarely we have\nto admit that there is no more indication of the inheritance of parentally\nacquired characters as regards customs, knowledge, habits and moral\ntraditions than there is of physical features. In fact, if such\nacquirements were inherited then we should soon have a race which would\nnaturally, spontaneously as it were, do what its ancestors did with\neffort. Yet we do not find the children in our schools reading, doing sums\nand developing proper social relations without ceaseless prompting and\nurging on the part of the teacher. Indeed I can testify that this\nnecessity carries over even into a university. In short, the habits and\nstandards of each generation have to be instilled into the succeeding\ngeneration.\n\n=No Cause for Discouragement.--=At first glance when we realize that\nnotwithstanding our individual advancement, that in spite of all our\npainstaking efforts toward self-improvement, we can not add one jot or\ntittle to the native ability of our children, that, aside from possible\nadvantageous germinal variations, they will have to start in at\napproximately the same level as we did, and like us will have to struggle,\nor be coaxed, pulled or spurred up to the higher reaches of attainments,\nwe are apt to feel discouraged and to look on heredity as the hand of fate\nwhich irrevocably bars progress. But there is another side to the picture.\nThis very fact of heredity which can not be altered at will is the\nconservative factor which maintains the excellence of our standard strains\nof plants and animals, and sustains man himself at his present level of\naccomplishment. While we are denied advancement through the efforts of the\nflesh, we are also largely protected from our misfortunes and follies, as\nwitness the non-inheritance of mutilations, of various maladies of\nextrinsic origin, or of personally acquired bad habits.\n\n=Improved Environment Will Help Conserve the Superior Strains When They Do\nAppear.--=If we can not hand on to our descendants a personally enhanced\nblood heritage, we at least can do our share toward building up a social\nheritage of established truth, of efficient institutions and of\nstimulating ideals, through which their dormant capacities may be led to\nexpand more surely and more effectively to their uttermost limits. Each\nadvance in such social heritage will tend more and more to create an\natmosphere which will make it sure that the occasional real progressive\nand permanent variations which occur from time to time will find adequate\nexpression and preservation in future lines of descendants. It will reduce\nthe numbers of our \"mute, inglorious Miltons\" by more certainly disclosing\nthe individual of exceptional talents and insuring for him an opportunity\nof revealing them to the best advantage. Above all, since surrounding\ninfluences are especially powerful on young and developing organisms, we\nshould realize that great care must be exercised in behalf of the young\nchild to secure an environment which is saturated with wholesome\ninfluences. For it is a rule of development that if the environment is\nfaulty the organism is impaired.\n\n\n\n\nCHAPTER VI\n\nPRENATAL INFLUENCES\n\n\n=All That a Child Possesses at Birth Not Necessarily Hereditary.--=We come\nnow to the more specific discussion of what may happen to offspring of\nmammals, and particularly man, in the interval between fertilization and\nbirth; that is, during the intra-maternal period. We have already seen\nthat anything affecting the offspring during this period has to be\nreckoned as environmental, our formula reading, Mammal = germ +\nintra-maternal environment + external environment. It is evident, then,\nthat all that a child possesses at birth is not necessarily hereditary,\nsince the unborn child may be influenced by conditions prevailing in\neither parent.\n\n=The Myth of Maternal Impressions.--=In order to clear the way for more\nurgent matters let us first inquire into the question of the production of\nchanges in the unborn child as a result of \"maternal impressions.\" As the\ntale generally goes, structural changes are produced in the unborn child\ncorresponding to some mental experience of the mother, usually a vivid\nimpression of strong emotion, but when a given individual is pinned down\nto sources, it is usually a case of hearsay.\n\nStock examples are: The mother sees a mouse with the result that a\nmouse-shaped birthmark occurs on the child; or she sees a crushed hand\nand in consequence bears a child later with some of the bones of the hand\nmissing; the mother touches her body when frightened and thus marks the\nunborn child on the corresponding part of the body; or she produces beauty\nin the child by long contemplation of a picture of a beautiful child; and\nso on almost endlessly. The favorite is usually the production of a red\nbirthmark or marks on the child's body by strong desire on the part of the\nmother for strawberries, tomatoes, etc.--the fruit must be red since the\nmark is red--or by fright from seeing a fire. As a matter of fact it is\nnot uncommon for the capillary blood vessels of the skin of a new-born\ninfant to remain dilated in spots instead of contracting as they normally\nshould do. The result is more or less of a red or \"flame\" spot. It is easy\nto see, therefore, why such birthmarks are so frequently referred back by\nthe credulous mother to her desire for or fear of some red object.\n\nAn analysis of the case of a child shuddering at the sight of peaches is\nof interest in this connection. The child showed the greatest aversion to\npeaches, particularly to the fuzzy covering. The mother's explanation was\nthat peaches were unusually plentiful the year the child was born and that\nshe had worked hour after hour at peeling and canning peaches shortly\nbefore his birth until she had become thoroughly sick of them. This\nacquired aversion on her part she believed had been transferred to the\nchild. A few questions revealed the fact, however, that the mother,\nherself, had never liked peaches and when asked if they were distasteful\nto any other member of her own family she exclaimed, \"Oh, yes, my mother\nwould shudder and shake if a peach were brought near her.\" And there we\nhave it. The idiosyncrasy was an inherited one as many similar\npeculiarities are. The mental impression produced in the mother by her own\nexperience with peaches had nothing to do with its occurrence in the\nchild.\n\nVery frequently also one encounters the mother who is sure she has\nengendered musical ability in her child by constant practise and study of\nmusic during pregnancy. The child is musical; what better evidence does\none want! It seems never to occur to such a mother that the child is\nmusically inclined because she herself is, as is evinced by her own desire\nin the matter even if she is not a skillful performer.\n\nWhen we take into account the extreme credulity of many people, the\nunconscious tendency of mankind to give a dramatic interpretation to\nevents where causes are not certainly known, the hosts of coincidences\nthat occur in life, and the multitude of cases where something should\nhappen but nothing does, we are compelled to believe that the whole matter\nof direct specific influence of the mother's mind on the developing fetus\nis a myth. After seeing the conditions which prevail in Mendelism, for\nexample, it will take strong faith to believe that a mother with duplex\nbrown eyes can \"think\" or \"will\" blue eyes on her baby, yet this would be\na mild procedure compared to some we are asked to accept by believers in\nthe transmission of maternal impressions. Most of all, however, when we\nrecall the actual relation between the embryo and the mother--a narrow\numbilical cord is the sole means of communication between the two--the\nphysical impossibility of a connection between some particular mental\nhappening of the mother and a corresponding specific modification in the\nfetus becomes evident. For there are no nerves in the umbilical cord, the\nonly path of communication between mother and fetus being the indirect one\nby way of the blood stream. Even this method of communication is limited\ninasmuch as the mother's blood does not circulate through the blood\nvessels of the fetus. Gaseous and dissolved substances are merely\ninterchanged through the thin walls of the capillary blood vessels in the\nplacenta.\n\n=Injurious Prenatal Influences.--=However, the denial that a particular\nmental impression of the mother is associated with a particular structural\ndefect in a child does not carry with it the implication that prenatal\ninfluences of all kinds are negligible factors. On the contrary any\ndeleterious effect which can reach the fetus through absorption from the\nblood of the mother may be of grave consequence. There is not the least\ndoubt that malnutrition or serious ill-health on the part of the mother\noften has a prejudicial effect on the unborn offspring. Severe shock or\ngrief, worry, nervous exhaustion, the influence of certain diseases,\npoisons in the blood or tissues of the parent, such as lead, mercury,\nphosphorus, alcohol and the like, may all act detrimentally, but they\noperate either by rendering nutrition defective, by direct poisoning, or\nby generating toxins in the blood of the parent which then poison the\nfetus. Among the latter may be mentioned the toxic products of\ntuberculosis and certain other bacterial diseases. Such factors operating\non the unborn young or even on the germ-cells may cause malformations,\narrests of development, instabilities of the nervous system, and general\nphysical or mental weakness. The effects are general, however, and not\nspecific.\n\nTo distinguish certain of these prenatal effects, particularly those of\ncertain diseases or poisons, from true hereditary influences they are\nfrequently spoken of as cases of _transmission_ rather than inheritance\nfrom parents. Some writers use the technical term _blastophthoria_, or\nfalse-heredity, extending the meaning so as to include also any damage\nthat might be inflicted on the germ-cells.\n\n=Lead Poisoning.--=By way of illustration of how certain cumulative\npoisons may act we may examine a tabulation of eighty-one cases of lead\npoisoning as reported by Constantin Paul (Fig. 29, p. 164).\n\nThe table requires little comment. The disastrous effects of such\npoisoning are apparent in every class of cases. The sixth class where the\nhusband alone was exposed to lead shows that the poison can operate\ndirectly through the germ-cell. Other observers note that in the children\nof workers in lead, there is a distressing frequency of feeble-mindedness\nand epilepsy.\n\nThat lead poisoning operating through the germ-cells of the father can\naffect the development of the young harmfully is well shown in Fig. 30, p.\n165, which is a photograph of two young rabbits from the same litter The\nwhite young one is from a normal albino mother mated to an albino father\nwhich had received lead treatment. The pigmented young one is from the\nsame albino mother by a normal pigmented father. Although the white\nfather was considerably larger than the pigmented father, nevertheless the\nyoung of the former, because of the harmful effects of the lead, is\ndistinctly smaller and less lively. A number of litters, each from the\nsame mother but in part from a lead-poisoned father and in part from a\nnormal father, have been secured. All show more or less the same results.\nThe experiments are still in progress in the department of experimental\nbreeding at the University of Wisconsin.\n\n  --------------------------------------------------------------------\n                       |Number of cases.\n                       |     +----------------------------------------\n                       |     |Number of pregnancies.\n                       |     |      +---------------------------------\n                       |     |      |Abortions, premature labor, and\n                       |     |      |  stillbirths.\n                       |     |      |     +---------------------------\n                       |     |      |     |Infants born living.\n                       |     |      |     |      +--------------------\n                       |     |      |     |      |Remarks.\n  ---------------------|-----|------|-----|------|--------------------\n  1. Mother showing    |     |      |     |      |One infant died\n  symptoms of plubism  |  4  |  15  |  13 |   2  | within 24 hours.\n                       |     |      |     |      |\n  2. Mother working in |     |      |     |      |\n  type foundry, all    |     |      |     |      |\n  of whose previous    |     |      |     |      |\n  pregnancies had      |     |      |     |      |Four of these died\n  been normal          |  5  |  36  |  29 |   7  | in first year.\n                       |     |      |     |      |\n  3. Mother who during |     |      |     |      |\n  period of work in    |     |      |     |      |After ceasing to\n  type foundry had     |     |      |     |      | work had\n  five pregnancies     |  1  |   5  |   5 |   0  | healthy child.\n                       |     |      |     |      |\n  4. Mother working    |     |      |     |      |When away from\n  intermittently in    |     |      |     |      | work for some\n  type foundry;        |     |      |     |      | period of time\n  while working        |     |      |     |      | gave birth to\n  there                |  3  |   3  |   3 |   0  | healthy children.\n                       |     |      |     |      |\n  5. Mother in whom    |     |      |     |      |\n  blue line on gum     |     |      |     |      |\n  the only sign of     |     |      |     |      |\n  lead poisoning       |  6  |  29  |  21 |   8  |\n                       |     |      |     |      |Of these, eight died\n  6. Husband alone     |     |      |     |      | in first year,\n  exposed to lead      |  ?  |  32  |  12 |  20  | four in second,\n                       |     |      |     |      | five in third.\n  --------------------------------------------------------------------\n\nFIG. 29\n\nTabulation of eighty-one cases of lead poisoning recorded by Constantin\nPaul (from Adami).\n\n\n[Illustration: Fig. 30\n\nPhotograph of young rabbits from the same litter, the smaller one stunted\nby lead-poisoning of its father (Courtesy of Professor L. J. Cole).]\n\n\n=The Expectant Mother Should Have Rest.--=The mere matter of rest on the\npart of the pregnant mother is, judging from the work of Pinard, a\nFrenchman, and his pupils, an important one. In a number of detailed\ninvestigations they have shown that rest on the part of the working mother\nduring the last three months before the child is born results in the\nproduction of markedly larger and more robust children than those born of\nmothers equally healthy but who have not had such rest. Moreover the\ndanger of premature birth is considerably lessened.\n\n=Too Short Intervals Between Children.--=Too short an interval between\nchildbirths would also seem to be an infringement on the rights of the\nchild as well as of the mother. Thus Doctor R. J. Ewart (\"The Influence of\nParental Age on Offspring,\" _Eugenic Review_, October, 1911) finds that\nchildren born at intervals of less than two years after the birth of the\nprevious child still show at the age of six a notable deficiency in\nheight, weight and intelligence, when compared with the children born\nafter a longer interval, or even with first-born children.\n\n=Our Duty to Safeguard Motherhood.--=Doubtless the unventilated factory\nand tenement also do their share, even though we can give no exact\nquantitative measure of it. Obviously, it becomes a civic duty to protect\nas much as possible all members of our social system from such injurious\nfactors as have just been discussed. It is particularly necessary to\nsafeguard mothers before confinement, especially working mothers.\n\n=Expectant Mothers Neglected.--=According to the claims of life insurance\nmen, expectant mothers are the most neglected members of our population.\nDoctor Van Ingen, of New York City, estimates that ninety per cent. of\nwomen in this country are wholly without prenatal care. Yet every\nprospective mother should be taught the probable meaning of such symptoms\nas headache, hemorrhages, swelling of the feet and disturbed vision. She\nshould realize the importance of submitting a sample of urine for analysis\nat least once a month before childbirth and twice a month for a while\nthereafter. She should be specially informed regarding work, exercise,\ndiet and dress. A recent government bulletin written by Mrs. Max West\nwhich may be had free by writing to the Children's Bureau, Department of\nLabor, Washington, D. C., gives much useful information on this subject.\n\n\nALCOHOLISM\n\n=Unreliability of Much of the Data.--=One of the most important poisons\nthat plays a prominent part among ante-natal influences is alcohol. But\nwhen it comes to a study of the problem of alcoholism from the standpoint\nof heredity and parental influences we meet with many difficulties,\nprominent among which are the inaccuracy and unreliability of many of the\nstatistics brought forward in this connection. Many of the results are\nvitiated by the prejudices of propagandists who propose to make a case\neither for or against alcohol as a beverage whether or not the facts\njustify their conclusions. When one tries to view the matter with an open\nmind he finds that there is a deplorable lack of statistics which are not\nsusceptible to more than one interpretation. However, using as much as\npossible what seems to be unbiased data, the evidence is almost wholly\nagainst alcohol as a beverage, at least to any immoderate extent.\n\n=Alcohol a Germinal or Fetal Poison.--=The bad effects as far as offspring\nare concerned reveal themselves in the main under the category of \"false\nheredity,\" i. e., germinal or fetal poisonings rather than of heritable\nchanges induced in the germ-cells. Most investigators feel that there are\ntoo many criminal, imbecile, insane and unhealthy persons among the\noffspring of drunkards to dismiss the matter as a coincidence. In an\ninvestigation of Imbault, for example, we find recorded of one hundred\ntuberculous children that while forty-one were of tuberculous parentage,\nthirty-six per cent, were the offspring of inebriates. Furthermore Imbault\ncites the observations of Arrive on 1,506 cases of juvenile meningitis to\nthe effect that this malady is twice as frequent in the children of\nalcoholic as in those of tuberculous parentage. It has been proved by\nNicloux (_L'Obstetrique_, Vol. 99, 1900) that in dogs and guinea-pigs\nalcohol passes through the placenta and may be detected in fetal tissues;\nhence it is in position to influence the fetus. He found that in a very\nshort time the amount of alcohol in the blood of the fetus about\nparalleled that in the blood of the mother.\n\n=Progressive Increase in Death-Rate of Offspring of Inebriate Women.--=In\nan investigation on the effects of parental alcoholism on the offspring,\nSullivan (_Journal of Mental Science_, Vol. 45, 1899) gives some\nimportant figures. To avoid other complications he chose female drunkards\nin whom no other degenerative features were evident. He found that among\nthese the percentage of abortions, still-births and deaths of infants\nbefore their third year was 55.8 per cent. as against 23.9 per cent. in\nsober mothers. In answer to the objection that this high percentage may be\ndue merely to neglect, and not to impairment of the fetus by alcoholism,\nhe points out the fact based on the history of the successive births, that\nthere was a progressive increase in the death-rate of offspring in\nproportion to the length of time the mother had been an inebriate, thus:\n\n  -------------------------------------------------------------\n                   |No. of|Per cent.|Per cent. dying|  Total\n                   |cases |born dead|   before 3    |percentage\n  -----------------|------|---------|---------------|----------\n  First births     |  80  |   6.2   |     27.5      |   33.7\n  Second births    |  80  |  11.2   |     40.8      |   50.0\n  Third births     |  80  |   7.6   |     45.0      |   52.6\n  Fourth and fifth | 111  |  10.8   |     54.9      |   65.7\n  Sixth to tenth   |  93  |  17.2   |     54.8      |   72.0\n  -------------------------------------------------------------\n\n=Views of a Psychiatrist on Alcohol.--=Forel, who for years was the\npsychiatrist at the head of a large insane asylum at Zurich, Switzerland,\nhas this to say about the effects of narcotic poisons and alcohol in\nparticular:\n\n    \"The offspring tainted with alcoholic blastophthoria suffer various\n    bodily and physical anomalies, among which are dwarfism, rickets, a\n    predisposition to tuberculosis and epilepsy, moral idiocy, and idiocy\n    in general, a predisposition to crime and mental diseases, sexual\n    perversions, loss of suckling in women, and many other misfortunes.\"\n\nIn another passage he[6] remarks as follows:\n\n    \"But what is of much greater importance is the fact that acute and\n    chronic alcoholic intoxication deteriorates the germinal protoplasm of\n    the procreators.... The recent researches of Bezzola seem to prove\n    that the old belief in the bad quality of children conceived during\n    drunkenness is not without foundation. Relying on the Swiss census of\n    1900, in which there figure nine thousand idiots, and after careful\n    examination of the bulletins concerning them, this author has proved\n    that there are two acute annual maximum periods for the conception of\n    idiots (calculated from nine months before birth); the periods of\n    carnival and vintage, when the people drink most. In the wine-growing\n    districts the maximum conception of idiots is enormous, while it is\n    almost nil at other periods. Moreover, these two maximum periods come\n    at the time of year when conception is at a minimum among the rest of\n    the population, the maximum of normal conceptions occurring at the\n    beginning of summer.\"\n\nAnother interpretation of Bezzola's results has been suggested to the\neffect that the license of these periods enables the defective members of\nthe community, such as the feeble-minded, an opportunity of mating more\nreadily and that consequently the result is direct inheritance of idiocy\nand allied defects instead of idiocy produced through alcoholic poisoning\nof the parental germ-cell.\n\n=Other Views.--=There are indeed many competent investigators who believe\nthat alcoholism in parents has little or no part in the direct production\nof mental defects in children. For instance, Tredgold quotes Doctor\nIreland's observations that although at New Year, when the fishermen\nreturn, the whole population of certain villages in Scotland gets drunk,\nthere is no noticeable excess of defectives born nine months later, and\nremarks further that, \"I have histories of idiots conceived under such\ncircumstances, but so I have of normal children, and my opinion is, that\nwhile this may be a cause in some cases, the number of instances in this\ncountry at any rate is exceedingly small.\" Again, Goddard, one of our best\nknown American students of feeble-mindedness, who has made careful study\nof this point under especially favorable conditions, feels that his data\ndo not prove that alcoholism of either the father or the mother causes\nfeeble-mindedness in the child. He concludes, \"Everything seems to\nindicate that alcoholism itself is only a symptom; that it for the most\npart occurs in families where there is some form of neurotic taint,\nespecially feeble-mindedness.\" Goddard, however, in common with many other\nobservers, notes that miscarriages and deaths in infancy are far higher\namong inebriates than among abstainers.\n\nDoctor Mjoeen cites an interesting parallel between the increase of\nfeeble-mindedness in Norway and a period from 1816 to 1835, when every one\nwas permitted to distil brandy. In some districts many of the farmers\ndistilled brandy from corn and potatoes, and in such regions during this\nperiod feeble-mindedness increased nearly one hundred per cent. Later the\nhome distillation of brandy was stopped. According to Doctor Mjoeen, \"The\nenormous increase in idiots came and went with the brandy.\" He is\ninclined to believe, however, that the alcohol operated injuriously mainly\non stocks already defective.\n\n=The Affinity of Alcohol for Germinal Tissue.--=Nicloux and Renault have\nshown that alcohol has a decided affinity for the reproductive glands. In\nindividuals who have recently taken alcohol the proportion of alcohol in\nthe gonads is soon almost equal to the amount found in the blood. Thus in\nexperiments on mammals it was found that the proportion of alcohol in the\novary to that in the blood was as three to five, and in the testis as two\nto three. This would afford abundant opportunity for alcohol to act\ndirectly on the spermatozoon or the ovum.\n\nA number of different investigators concur in finding that the germ-glands\nof the male human inebriate in many cases show more or less atrophy and\nother degenerative changes. In guinea-pigs which have been repeatedly\nintoxicated with alcohol, Stockard found that while he could detect no\nvisible abnormality in the gonad, nevertheless their defective and\nweakened progeny showed that the germ-cells had been affected.\n\n=Innate Degeneracy Versus the Effects of Alcohol.--=Many observations on\nhuman beings have been brought forward which at first sight seem to\nindicate that noticeable defects, particularly mental and nervous, occur\nwith appalling frequency in children resulting from conception during\nintoxication, although, unfortunately, the evidence is rarely clear as to\nwhether the defects are really due to the effects of the alcohol or to the\nfact that the parent or parents were degenerate to begin with.\n\nA very interesting human case cited by Forel on the authority of\nSchweighofer is that of a normal woman who had three sound children when\nmarried to a normal man. After the death of this husband she married an\ninebriate by whom she had three other children. One of these suffered from\ninfantilism, one turned out to be a drunkard, and the third became a\nsocial degenerate and drunkard. Moreover the first two contracted\ntuberculosis, although hitherto the family stock had been free from this\nmalady. Ultimately the woman married again and by this third husband, who\nwas normal, she again had sound children. Similar cases might be cited,\nas, for example, a record of eighty-three epileptics, of whom sixty had\ndrunken parents, but it can be urged against all of them, of course, that\nthe defective offspring were due to an innate degeneracy of the drunken\nparent which made him a drunkard rather than to the effects of the alcohol\nhe took. While one is skeptical as to the validity of this objection in\nall of the many cases which occur with such monotonous frequency in man,\nthere is no way of escaping such an interpretation with the evidence at\nhand. It must be admitted, moreover, that there are many families with one\nor both parents alcoholic in which the children are not mentally\ndefective.\n\n=Experimental Alcoholism in Lower Animals.--=Many of the objections that\nexist in the case of man, however, do not apply in that of lower animals.\nIf normal animals are experimentally alcoholized and are shown to produce\ndefective offspring under such conditions, then in their cases at least,\nthe disorders in the offspring must be due to the effects of alcohol and\nnot to an innately degenerate condition of the parent. Disorders similar\nto some of those seen in the children of alcoholics do actually result in\nalcoholized animals of one kind or another.\n\nAgainst the earlier experiments on animals it has been urged that too few\nindividuals were used to give conclusive results, but this objection can\nnot be brought against the recent experiments of Stockard. While he has\npublished accounts of his work in various scientific periodicals lately,\nthe reader will find a full statement of his own experiments, together\nwith a review of the whole subject of experimental alcoholism in animals\nand the effects on progeny in _The American Naturalist_, Vol. XLVII,\nNovember, 1913, together with a useful bibliography.\n\nBefore taking up Stockard's results we may select a few of the more\nsignificant experiments made earlier by other investigators.\n\nLaitinen alcoholized rabbits and guinea-pigs. He found that the treated\nindividuals had more still-born young than the control, and also that\ngrowth of the living young was retarded. His alcoholized rabbits and\nguinea-pigs produced more young than did the normal individuals used as a\ncontrol. Laitinen's studies on man, together with three other studies of\nthe Eugenics Laboratory in London, show that in man also more children are\nborn to alcoholics than to normal parents. Goddard's investigations in\nAmerica corroborate this fact.\n\nCeni found that only 43 per cent. of the eggs from alcoholized fowls\ndeveloped normally, as against 77 per cent. of normal development in the\ncontrols. Moreover the eggs of alcoholic fowls were shown to be less\nresistant to adverse conditions than normal eggs from the fact that\nfluctuations of temperature at the beginning of incubation kept all the\nalcoholic eggs from developing perfectly, while 27 per cent. of the\ncontrol eggs developed normally under the same adverse circumstances.\n\nHodge made a pair of dogs alcoholic. Of 23 pups obtained from the pair, 8\nwere deformed and 9 were dead; 4 alone were viable. From a control pair of\ndogs 45 pups were obtained, of which 4 were deformed, none were born dead,\nand 41 were viable.\n\n=Stockard's Experiments on Guinea-Pigs.--=Stockard's experiments\ndemonstrate that the offspring of mammals may be injured or modified in\ntheir development by treating either parent repeatedly with alcohol. The\nguinea-pigs used in the experiment were all first tested by normal matings\nand found to yield normal offspring. The alcohol was given to them by\ninhalation. It was found to be readily taken into the animals' blood and\nto produce intoxication. While guinea-pigs alcoholized in this way as\noften as six times a week for two and one-half years would maintain their\nown bodily vigor and health apparently, the deleterious effects on their\nprogeny were marked. The defects were general rather than specific,\nalthough the central nervous system and special sense organs were\napparently affected most.\n\nOut of 119 total young produced by the alcoholic animals, only 52, or less\nthan 44 per cent., survived, whereas out of 64 young produced from normal\nparents used as a control for the experiment, 56, or over 87 per cent.,\nsurvived. In some cases alcoholic males were mated with normal females, in\nother, alcoholic females with normal males. In still other instances both\nparents were alcoholic.\n\nThe results are summarized in the accompanying table (Fig. 31), taken from\nStockard's paper:\n\n  CONDITION OF THE OFFSPRING FROM GUINEA-PIGS TREATED WITH ALCOHOL\n\n  -----------------------------------------------------------------\n                      |Number of Matings\n                      |     +--------------------------------------\n                      |     |Negative Result or Early Abortion\n                      |     |    +---------------------------------\n                      |     |    |Stillborn Litters\n                      |     |    |    +----------------------------\n                      |     |    |    |Number Stillborn Young\n                      |     |    |    |      +---------------------\n                      |     |    |    |      |Living Litters\n                      |     |    |    |      |    +----------------\n                      |     |    |    |      |    |Young Dying Soon\n                      |     |    |    |      |    |  After Birth\n                      |     |    |    |      |    |      +---------\n  Condition of        |     |    |    |      |    |      |Surviving\n   the Animals        |     |    |    |      |    |      |  Young\n  --------------------|-----|----|----|------|----|------|---------\n  Alcoholic [male] by |     |    |    |      |    |      |\n    normal [female]   |  59 | 25 |  8 |  15  | 26 |  21  |  33\n  Normal [male] by    |     |    |    |      |    |      |\n    alcoholic [female]|  15 |  3 |  3 |   9  |  9 |   9  |  10\n  Alcoholic [male] by |     |    |    |      |    |      |\n    alcoholic [female]|  29 | 15 |  3 |   6  | 11 |   7  |   9\n  SUMMARY             | 103 | 43 | 14 |  30  | 46 |  37  |  52\n  Normal [male] by    |     |    |    |      |    |      |\n    normal [female]   |  35 |  2 |  1 |   4  | 32 |   4  |  56\n  2d generation       |     |    |    |      |    |      |\n    by normal         |   3 |  0 |  0 |   0  |  3 |   0  |   4\n  2d generation       |     |    |    |      |    |      |\n    by alcoholic      |   3 |  0 |  2 |   5  |  1 |   0  |   2\n                      |     |    |    |1 def.|    |      |\n  2d generation       |     |    |    |      |    |      |\n    by 2d generation  |  19 |  7 |  0 |   0  | 12 |   6  |  13\n                      |     |    |    |      |    |1 def.|\n  Female treated      |     |    |    |      |    |      |\n    during pregnancy  |   4 |  0 |  0 |   0  |  4 |   1  |   7\n  -----------------------------------------------------------------\n\nFIG. 31\n\nTable showing condition of the offspring from guinea-pigs treated with\nalcohol (after Stockard).\n\nLines four and five give a comparison between the 103 total matings of all\ntreated individuals and 35 normal matings. In the first case almost 42 per\ncent. of the matings gave negative results or early abortions, whereas in\nthe normal control matings, failure to yield a full-term litter occurred\nin only two cases. The 103 matings of alcoholic animals gave only 46\nliving litters, or about 45 per cent. On the other hand the 35 control\nmatings produced 32 living litters, or 91-1/2 per cent. It will be\nobserved also that from such of the 103 matings of alcoholics as produced\nyoung there were 30 still-born, 37 which died soon after birth, and only\n52 surviving young, whereas from the 35 matings of normal individuals\nthere were only 4 still-born young, 4 which died soon after birth, and 56\nsurviving young.\n\nThe bottom line of the table, although, as Stockard points out, containing\ntoo few cases to prove wholly convincing, indicates that alcoholizing\nerstwhile normal females during pregnancy was not particularly harmful to\nthe embryos _in utero_.\n\nSome of the most interesting results were obtained when offspring termed\nsecond generation animals, derived from alcoholic parents though not\nthemselves treated with alcohol, were mated in various ways. When such\nindividuals were mated with normal individuals, although the litters were\nsmall, the results were normal, the normal mate having seemingly\ncounteracted any defects which might have lurked in the second generation\nanimal. On the other hand, out of three matings of second generation\nanimals with alcoholic individuals, two produced still-born young, of\nwhich one was markedly deformed, while the third yielded two living young.\n\nHowever, the most striking results were obtained when two second\ngeneration individuals, the offspring of alcoholic parents, were bred\ntogether. Although themselves untreated, these individuals, of which 19\nmatings were made, produced as many or more defective young than did their\nalcoholic parents. Seven of the matings were unfruitful. The remaining 12\nmatings gave living litters consisting of 19 individuals in all. Six of\nthese showed various nerve disorders (spasms, epileptic-like seizures,\netc.) soon after birth; one was eyeless and otherwise deformed.\n\n=Stockard's Interpretation.--=Stockard's interpretation of his experiments\nis as follows: \"Mammals treated with injurious substances, such as\nalcohol, ether, lead, etc., suffer from the treatments by having the\ntissues of their bodies injured. When the reproductive glands and\ngerm-cells become injured in this way they give rise to offspring showing\nweak and degenerative conditions of a general nature, and every cell of\nthese offspring having been derived from the injured egg or sperm-cell are\nnecessarily similarly injured and can only give rise to other injured\ncells and thus the next generation of offspring are equally weak and\ninjured and so on. The only hope for such a line of individuals is that it\ncan be crossed by normal stock, in which case the vigor of the normal\ngerm-cell in the combination may counteract, or at any rate reduce, the\nextent of injury in the body cells of the resulting animal.\"\n\nHe also believes that various deformities and developmental arrests such\nas harelip and cleft-palate may similarly be cases of transmission rather\nthan true inheritance, due to the weakening of the germ-cells in some way,\nor to some lack of full vigor in the uterine environment.\n\n=Further Remarks on the Situation in Man.--=Returning now to the question\nof alcoholism in man, it seems in view of the strong circumstantial\nevidence in the case of man himself, together with the result of\nexperiments on animals, that little doubt remains that excessive\nalcoholism might result in the production of defective offspring. On the\nother hand an antecedent degeneracy or neural instability undoubtedly\nplays an important part in many cases, in the original production of\ndrunkards, and when such occurs, it, as well as the direct effects of\nalcoholic poisoning, must be reckoned with in the effects on progeny.\nStudies carried on by Pearson, Elderton and Barrington of the Eugenic\nLaboratory in London lead these investigators to the conclusion that\nextreme alcoholism is a _result_ not a _cause_ of degeneracy. That is, the\ndegeneracy is due to the defective stock, not to alcohol. They cite in\nevidence their records of four thousand school children of alcoholic and\nof sober parents, which fail to show any unfavorable effect of alcohol on\noffspring. Some of their critics, however, maintain that they did not\nchoose subjects who were sufficiently alcoholic to give the injurious\nresults that might legitimately be expected among the offspring of\nexcessive drinkers or habitual drunkards.\n\nWhere children show a hereditary inclination toward drink, unquestionably\none of the strongest factors is the inheritance of the same disposition,\nthe same unstable nervous constitution and its accompanying lack of\nself-control which led the parent to drink, rather than the inheritance of\nthe effects of the drink on the parent. For in many cases a parent may not\nbecome a drunkard until after the children who also become drunkards are\nborn. That the tendency to drink immoderately is frequently due to a\nstrain of feeble-mindedness or epilepsy becomes more evident every day.\nIn many of the so-called \"periodical\" drunkards, the accompanying features\nof their periodic attacks of drink-craving, such as clouding of memory,\nrestlessness and depression, are those commonly associated with ordinary\nepileptic attacks.\n\n=Probably Over Fifty Per Cent. of Inebriety in Man Due to Defective\nNervous Constitution.--=Branthwaite, an English authority on drunkenness,\nfinds that about sixty-three per cent. of the inebriates who come to his\nnotice are mentally defective. In alcoholic insanities heredity is a\npotent factor. It is coming to be realized more and more that pronounced\nalcoholism is due in a large percentage of cases, perhaps over half, to a\ndefective nervous make-up. While it is true that many drunkards would not\ndevelop without free access to alcohol, on the other hand many would never\ndevelop without a bad heredity back of them, which gives them a peculiar\nnervous constitution that renders alcohol an undue stimulus. In a recent\nreport of the New York State Hospital Commission it is stated that in\nfifty-four per cent. of the cases of alcoholic insanity, a family history\nof insanity, epilepsy or nervous disease exists. Thus in the presence of\nalcohol most of these unfortunates are helpless pawns of a hereditary\nweakness.\n\nSo when the question of alcoholism is viewed from all angles, the children\nof the human drunkard would seem to run a double menace of misfortune,\nsince they may be subject both to the direct poisoning effects of alcohol\nand the results of an inheritable degeneracy.\n\n=Factors to Be Reckoned With in the Study of Alcoholism.--=In any\nthoroughgoing study of alcoholism in man many factors will have to be\nreckoned with. First of all there is the question of inherent lack of\ncontrol. This is probably the principal thing inherited where heredity\ntruly enters as a factor. That example and social environment are\nimportant factors in addition to or in place of heredity is clear, too,\nwhen we observe that often it is the boys only who take after a drunken\nfather, for there is no evidence that the inherited tendency when it\nreally exists is at all sex-linked. Again, in certain occupations carried\non under unwholesome influences relief is frequently sought in alcoholic\nstimulants, and such custom may easily crystallize into habit.\nFurthermore, the accustoming young children to doses of alcohol, or the\nunborn young to alcohol through the body of a drunken mother, may be\nstrongly contributory toward establishing inebriety in certain cases. As\nwe have seen from an abundance of experimental data on animals, moreover,\nthe nurture effects on germ-cells may result in the production of weakened\noffspring. Such offspring in the case of man are probably less able to\nwithstand temptations of all kinds and hence readily succumb to the\nhabit-forming effects of alcohol if once its use is begun. Lastly, it must\nnot be forgotten that alcoholism in the father usually means poverty and\nthe subsequent accompaniment of malnutrition and neglect of the children,\nand this in itself may not only account for poor development of the\nlatter, but may also be strongly contributory toward establishing the\nhabit of alcoholism in them.\n\nAn inherent bias plus most of the other conditions just enumerated is the\nnot unusual lot of the offspring of drunkards.\n\n=Venereal Diseases.--=There is yet another very considerable class of\nmaritally unfit who in any conscientious discussion of unfitness for\nmarriage or of racial improvement must be considered. I refer to those who\nare afflicted with the diseases which are inseparably associated with the\nso-called \"social evil.\" To _gonorrhea_, one of the most prevalent of\nthese diseases, more than one-fourth of our total one hundred and ten\nthousand blind in the United States are said to owe their affliction.\nMilder types of eye disease may also result from such infections. As much\nas eighty per cent., or some say practically all blindness in children\nborn blind is caused by it, the infection occurring at the time of birth\nor within a few days thereafter. The terrible consequences of this disease\nto the innocent wife would alone make its discussion imperative.\n\n=The Seriousness of the Situation.--=Unfortunately the insidious nature of\ngonorrheal infections is unknown to most persons. A cure is apparently\neffected, yet as a matter of fact the germs may live for years and, if in\nthe male, later be transmitted to the wife, subjecting her to a future of\ninvalidism and misery. Reliable statistics from various medical\nauthorities reveal the appalling fact that seventy-five per cent. or more\nof the surgical operations for inflammatory pelvic disorders peculiar to\nwomen, such as pus tubes and peritonitis, are attributable to this\ndisease, as is also the involuntary sterility of forty-five per cent. of\nchildless women. Unwelcome as the fact is there is an abundance of\nevidence to show that a large percentage of men in particular have at\nsome period of their life been infected with venereal disease. Of our\nfourteen million males in the United States under the age of thirty we\nfind estimates by some specialists in venereal diseases to the effect that\nfive million of them, that is, one out of three, suffer from some one of\nthe social diseases or their consequences. Doctor Hugh Cabot, one of the\nchief surgeons of the Massachusetts General Hospital at Boston, a member\nof the faculty of the Harvard Medical School and president of the American\nAssociation of Genito-Urinary Surgeons, has this to say about the\nsituation: \"We have of late years heard much about the frequency and\nserious consequences of tuberculosis; it has been dubbed the 'white\nplague,' and so active has been the campaign that a wide-spread\nunderstanding of this serious disease has resulted. It may safely be\naverred that in the urban population at least there are two, and perhaps\nthree, individuals with syphilis to every one with tuberculosis. The\nfrequency of gonococcus infection is much higher.\" He believes that over\nhalf the male population acquire a gonococcus infection at some period of\ntheir career. While as a layman, one can not but feel that a specialist's\nestimate may run unduly high because of the fact that he is encountering\nan inordinate proportion of such maladies every day, still such\nspecialists are in position to get at the truth as no other person can and\ntheir calculations are probably not grossly in error. In any event any one\nwho has progressed in worldly knowledge beyond the naivete of a child must\nrecognize the appalling prevalence of these maladies.\n\n=Infantile Blindness.--=So serious has the matter of infantile blindness\nbecome that some state boards of health and some city health departments\nsupply all physicians and midwives with specially prepared packages\ncontaining cotton and nitrate of silver solution for preventive or\ncurative treatment of the eyes of all new-born children. At the time of\nthe first bath each eye is carefully washed with a separate pledget of\ncotton saturated with boric acid solution. Each then receives a drop of\nthe silver solution, which is made just strong enough to kill any\ngonococci that might be present without itself inflaming the eye. Water\nused in bathing the baby's body of course is not allowed to come in\ncontact with its eyes. Such treatment should be given every child no\nmatter how unsuspicious the circumstances may be. German authorities who\nhave been following this method now for some years assure us that\nnineteen-twentieths of the blindness of infancy can thus be prevented.\n\n=Syphilis.--=As to _syphilis_, another and even more terrible of these\ndiseases, we have before us the absurd fact that while thousands upon\nthousands of dollars are being spent to establish a rigid inspection and\npreventive measures against the spread of a very similar disease in the\nhorse, this malady in man is allowed to pass unchallenged and we are\nconfronted by the gruesome certainty that there are hundreds of these\ndiseased persons about us to-day who, on their mere affirmation that they\nare unmarried and of age, will be given the right to marry and thus\nproduce families of infected children irrevocably doomed to early death or\nto lifelong misery.\n\nWhile syphilis is most commonly spread through relations between the\nsexes, it may be acquired in various other ways, as for example, through a\ncut in shaving with the same razor an infected individual has used. It is\ncommonly transmitted from parent to child. Practically every prostitute is\na center of dissemination. Katherine Bement Davis has shown in her studies\nmade at the New York State Reformatory for Women that while ordinary\nclinical tests show that apparently only twenty-one per cent. of these\nwomen are infected with venereal disease, more careful laboratory tests\nshowed at least ninety per cent. to be infected.\n\nSyphilis is caused by _Treponema pallidum_, a small unicellular animal\nparasite. Given access to the blood by any means whatever, possibly even\nthrough an abrasion in the lip by means of a kiss, it multiplies rapidly\nand any part or organ of the body may be attacked. Usually a small sore\noccurs at the point of entrance to the body, but often it heals up readily\nwith little indication of the seriousness of the infection.\n\nThe development of the malady is insidious and long continued. As a matter\nof clinical convenience physicians divide its progress into successive\nstages although in reality the transitions are frequently variable and ill\nmarked. The symptoms that arise within the first few months or even years\nare readily controlled by appropriate treatment, but to insure a cure\nprolonged and most thoroughgoing treatment is imperative. The symptoms\ndisappear so completely after a short period of treatment that it is very\ndifficult to persuade the average patient that he is not yet cured. Two\nyears at least are none too short a period of treatment, yet the majority\nof patients, fully convinced that they are merely being exploited by the\nphysician as a source of revenue, drift away at the end of a few months.\nAs a matter of fact, however, the germs usually persist long after the\nobvious symptoms of the disease have disappeared, and in consequence many\nof the most serious results of syphilis may not manifest themselves for a\nperiod of perhaps ten, twenty or thirty years.\n\n=Some of the Effects.--=It is now known that _paresis_, also termed\ngeneral paralysis or softening of the brain, is probably invariably due to\nsyphilis. The work of Flexner and Noguchi on _paresis_ and _tabes\ndorsalis_ show that always in such afflictions the tissues of the central\nnervous system have been invaded by the parasite. The original infection,\nhowever, may have occurred so long before as to have been almost forgotten\nby the patient. Thus many an apparently robust man is stricken down in the\nprime of life. Earlier and prolonged treatment would in all probability\nhave eradicated the germs and thus prevented the mental breakdown, which\ncan not be cured by any known treatment. Postmortem examination always\nshows that the _Treponema_ has wrought wide-spread damage in the brain.\nThe frequency of paresis may be realized when one learns that in some\nregions it is responsible for about one-fifth of all cases of insanity\nsent to hospitals for the insane. It ranks next to the highest as a cause\nof insanity. Statistics show that in the state of New York more deaths\nresult annually from paresis than from smallpox, tetanus, malaria,\ndysentery and rabies all combined.\n\nIn some cases the disease attacks the membranes of the brain and the small\nblood vessels giving rise to a still different type of mental disorder.\nPractically all patients with _locomotor ataxia_ owe their condition to an\nantecedent syphilis. Moreover it is one of the important causes of\n_arterio-sclerosis_, or hardening of the blood vessels, and is also a\nprominent factor in certain forms of heart-disease, as well as by no means\nan unimportant cause of blindness in children.\n\nAs to specific cases of the effects of this disease on descendants the\nliterature of the subject is crowded full. While it is needless to conduct\nthe reader through a chamber of horrors by reviewing clinical cases, it is\ndesirable to point out in a general way some of the effects. Doctor George\nH. Kirby, director of Clinical Psychiatry, Manhattan State Hospital, says:\n\n    \"We find that when either the father or the mother suffers from\n    paresis that many other members of the family may be infected with\n    syphilis, and furthermore, we find that a large number of children in\n    these families are feeble-minded, nervous, or in other ways abnormal.\n    Doctor Plant examined a group of 100 children, the offspring of cases\n    of paresis, and found that 45 per cent. were plainly damaged mentally\n    or physically, or in both fields; the blood test showed that one-third\n    of these 100 children had the syphilitic poison in their systems.\n\n    \"Another investigator found in a group of 139 children, the\n    descendants of parents who had syphilitic nervous disease, that over\n    25 per cent. were definitely feeble-minded or affected with some\n    serious nervous disorders.\n\n    \"Other studies indicate that there exists a close relation between\n    syphilis and many of the hitherto unexplained cases of\n    feeble-mindedness, including idiocy, imbecility, infantile paralysis,\n    and some forms of epilepsy. While the question is not yet settled, it\n    appears that syphilis is the real cause of many of these cases of\n    mental defect in children.\"\n\nStill other investigators give details of physical afflictions and\ndistortions, of suppressed development, of inordinate percentages of\nstillbirths--perhaps the most merciful lot for the little victims--but\nsufficient has been said to indicate the full horror of the situation.\n\nGoddard,[7] although not minimizing the terrible nature of the disease,\nfinds little evidence in his studies that syphilis in parents is a\nspecific cause of feeble-mindedness.\n\n=A Blood Test.--=Fortunately a delicate blood test known as the Wasserman\ntest has been discovered by means of which, through an examination of a\nfew drops of blood, any trace of syphilitic poison which exists in the\nbody may usually be detected. This is true even though the individual may\nat the time show no visible symptoms of syphilis. The test is therefore of\ngreat value in detecting the latent germs of syphilis in individuals who\nhave apparently been cured, and also often in making an early diagnosis of\nparesis. The Wasserman test, however, is reliable only in the hands of a\nskilled operator. It may occasionally give a positive reaction when\nsyphilis does not exist and on the contrary a negative when it is present.\nThe _luetin_ test is also now applied by some specialists, but is too new\na test to have come into general use. It works on the same principle as\nthe tuberculin test for tuberculosis. Some army physicians now also give\nwhat is termed a provocative Wasserman. That is, in a suspicious case\nwhich gives only negative results by an ordinary Wasserman, they can get,\nif syphilis really exists, a positive reaction after giving small doses of\npotassium iodide or salvarsan.\n\nIt should be well understood by every one that syphilis is usually curable\nprovided the patient is given modern scientific treatment by a _competent_\nphysician. I emphasize competent because there are so many quacks in this\nfield that one undergoing treatment can not be too careful in assuring\nhimself of the competency of the physician. In even a case of long\nstanding, where the symptoms have been in abeyance for a number of years,\nthe disease can be cured provided it has not developed into an active\ncerebro-spinal type, and even the latter can be much benefited by proper\ntreatment. The great danger of the cerebro-spinal type is that it will\nresult in paresis or locomotor ataxia.\n\nAs long as the blood of a patient shows a _positive_ Wasserman reaction,\nmarriage should certainly not be consummated. If after a proper course of\ntreatment by a well-informed physician, the patient shows a _negative_\nWasserman when tested by a competent examiner, he probably would not\ninfect his wife or offspring, although prudence would require that he wait\nat least six months or a year before marriage, and marrying then only if\nlater tests remain negative.\n\nThe only way for a patient to be sure that he is not harboring the\ncerebro-spinal form would be to have a spinal puncture made and the\ncerebro-spinal fluid examined. While the cerebro-spinal phase often does\nnot occur until long after the primary infection, cases are known in which\nit has appeared within a few weeks. Evidence that the central nervous\nsystem is frequently invaded early in the course of the disease is\nincreasing. Marriage of an individual suffering from the cerebro-spinal\nform should not take place, since such a one is almost sure to become a\nburden on the family or the state.\n\n=Many Syphilitics Are Married.--=It may seem to some that in a treatise on\nbeing well-born the subject of syphilis might be ignored as not being\nespecially pertinent, but the supposition that no considerable percentage\nof syphilitics marry is not borne out by the facts. Seventy-five per cent.\nof men with insanity due to syphilis who are admitted to hospitals are\nmarried. The insanity in such cases is mainly the result of infections in\nearlier years, often long before marriage. While syphilis, strictly\nspeaking, is not inherited, that is, does not become part and parcel of\nthe germ-plasm, still the frequency of its direct transmission to\noffspring is so appalling that the outcome, as far as the immediate child\nis concerned, is quite as disastrous as the most thoroughgoing real\ninheritance could be.\n\n=Why Permit Conditions to Continue as They Are?--=When one faces the\neasily ascertained facts regarding venereal disease, it seems incredible\nthat we, an intelligent people, can go on complacently handing our\ndaughters and sisters over to the surgeon's knife and a life of personal\nmisery, and even in not a few instances to become mothers of incurably\ndefective children, yet the dire fact confronts us that we do. We can no\nlonger excuse ourselves on the plea of ignorance, for the grisly record\nmay now be read in many medical and not a few popular treatises, and we\nfind the theme entering even into the modern drama, as witness Brieux's\n_Damaged Goods_. Further indifference to these conditions can only be\nattributed to culpable apathy or prudery.\n\nThe extreme dangers to which parents are subjecting their daughters if\nthey do not demand a clean bill of health on the part of their prospective\nhusbands are obvious. Fathers and mothers perfectly willing to inquire\ninto their future son-in-law's social connections, his income, securities,\nor business chances become strangely \"modest\" when it comes to determining\nwhether he is physically fit for marriage.\n\nOne great cause of ignorance in the past was the prudish taboo against\nfrank discussions of venereal diseases which has thrown the veil of\nsilence about the subject. To-day, however, it is coming to be recognized\nthat these maladies are diseases and not a standard of social propriety,\nand that like most other diseases the surest way to secure prevention and\ngradual eradication is through the enlightenment of the public. They are\nprevalent in all classes of society. Moreover, it must not be forgotten\nthat there is no form of venereal disease which may not be innocently\nacquired. Even where acquired through transgression of moral law an\nignorant attitude toward the sexual instinct is often at the bottom of the\ndifficulty.\n\n=Medical Inspection Before Marriage.--=Ante-nuptial medical inspection is\ncertainly as necessary to the welfare of society as the certification of\nage and of the single state now required by law. No one objects to a\nmedical examination pertaining to venereal and other diseases when it\ncomes to taking out a life insurance policy, and why there should be any\nmore objection to it as a preliminary to marriage is a mystery. A few\nstates already have compulsory ante-nuptial medical inspection. The laws\nhave been enacted too recently to judge adequately of their working. There\nhas been much debate in Wisconsin as to whether their law (Chapter 738,\nLaws of 1913), which went into effect January 1, 1914, is constitutional\nand whether it requires a Wasserman test. The Wisconsin law applies to\nmales only. The Supreme Court of the state has declared it constitutional\nand that its requirement of \"the application of the recognized clinical\nand laboratory tests of scientific search\" involves only such examination\nas the ordinary licensed physician is equipped to make and can reasonably\nbe expected to make for three dollars, the maximum fee specified in the\nlaw.\n\nA number of the physicians of the state are still dissatisfied with the\nwording, although most do not oppose the principle of the law. Many\nbelieve that it should apply to the women as well as to the men, and\nothers feel that the law should be extended to cover still other kinds of\nmarital unfitness. Most of the practitioners with whom I have discussed\nthe matter appreciate the motive underlying the law and are endeavoring to\nmake it successful.\n\nThe general public of the state as a whole seems to be in favor of the\nprovision. At least one hears much favorable comment and little\ndissension among those who understand its purpose. The very controversy\nover it which sprang up after its passage proved to be of great benefit in\nthe education of the public regarding the necessity of such measures. Such\nphysicians as I have been able to question report that the candidates for\nmarriage rarely object to the requirement, but on the contrary strongly\nfavor it. Especially where they have suffered from venereal disease\nearlier in life most are eager to know their condition and to have medical\nadvice. To my own mind this last fact is the most significant of all, as\nit will give every candidate for marriage a chance to know the truth. Most\nmen are not so much brutal or vicious as ignorant in such matters. The\nvast majority of those unfit for marriage as a consequence of venereal\ndisease will, when they realize the danger their condition imposes on wife\nand children, take every possible means to put themselves into proper\ncondition.\n\nDesirable as the Wasserman test may be, it requires special laboratory\nfacilities and equipment as well as a specially trained examiner to make\nit a reliable test. Moreover it can not be given by the general\npractitioner for the very moderate fee that must obtain in a pre-nuptial\nexamination compelled by law. If it or the serum test for gonorrhea are to\nbe applied then the legislative body of the state will find it necessary\nto establish a special public laboratory or laboratories for their\napplication. This, however, is not a matter of particular difficulty and\nwould be capital well invested in any state.\n\n=The Perils of Venereal Disease Must Be Prevented at Any Cost.--=However,\nno matter what the cost may be to the state, no matter what the exaction\nfrom the individual, the grave perils of venereal disease to society\n_must_ be prevented. We owe it to the cause of humanity that there be\nfewer victims born into a world of eternal night, that from a parentage of\npolluted blood there spring no longer hosts of children with feeble\nmisshapen bodies or with tarnished intellects, death-marked at the door of\nlife.\n\n=Bad Environment Can Wreck Good Germ-Plasm.--=In conclusion it is evident\nfrom our discussion of prenatal influences that not all of being well-born\nis concerned with heredity in its proper sense, since the unborn young may\nbe influenced either directly or indirectly by environmental conditions\nwhich are in no sense products of heredity, although as far as the\nimmediate child is concerned the result may be quite as disastrous where\nthe influence is a baneful one. As to the production of beneficial\nprenatal effects, while parents can do nothing toward modifying favorably\nsuch qualities as are predetermined in their germ-plasm, nevertheless they\nmust come to realize that bad environment can wreck good germ-plasm. They\ncan see to it that they keep themselves in good physical condition by\nwholesome temperate living, and thereby insure as far as possible healthy\ngerm-cells for the conception and good nutrition for the sustenance of\ntheir progeny. Their one sacred obligation to the immortal germ-plasm of\nwhich they are the trustees is to see that they hand it on with its\nmaximal possibilities undimmed by innutrition, poisons or vice.\n\n\n\n\nCHAPTER VII\n\nRESPONSIBILITY FOR CONDUCT\n\n\nSince both physical and mental attributes are unquestionably inherited, it\nbecomes a matter of importance to inquire into the nature of the entity we\ncall personality. To what extent is human conduct a product of parentage?\nAlthough apparently free agents are we in reality only by infinitely\nsubtle indirections making the responses, forming the habits, establishing\nthe characters which result merely from the blind impulsions of an\ninherent constitution? If so, who is praiseworthy, who blameworthy? Are\nmen\n\n  \"But helpless pieces of the Game He plays\n  Upon this chequer-board of Nights and Days.\"\n\n=All Mental Process Accompanied by Neural Process.--=Whatever the ultimate\ndecision of psychologists may be regarding the relation of mind to the\nsensory and nervous mechanism of man it is certain that there is so close\nan association between them that the least alteration in the mechanism\nmeans a parallel effect in the mind, or in the words of Huxley, \"every\npsychosis is definitely correlated with a neurosis.\" The rind or _cortex_\nof gray matter which constitutes the surface of the large cerebral\nhemispheres of the human brain is regarded as the seat of consciousness.\nThe development of the mental powers in the infant is dependent on the\ndevelopment of the elements of this cortical substance and the waning of\nthe mental faculties in old age goes hand in hand with its atrophy.\nAbnormal arrangements, injuries or omissions in it mean mental\nunsoundness. How the activity of the structural mechanism gives a reaction\nin consciousness is not understood, but we know that in the living being\nthe two phenomena are inseparably linked. Whether we accept the hypothesis\nthat consciousness is an actual product of the structural mechanism or the\nhypothesis that the latter is only an instrument for the manifestations as\nconsciousness of an outside force or entity, just as the telegraphic\ninstrument manifests the existence of electricity, is neither here nor\nthere for our purposes. On either supposition the degree and manner of\nexpression are determined by the structure of the mechanism. Our main\nproblem is to decide as nearly as possible how much of the mechanism is\nrigidly inherited, how much is at birth largely undestined, so that its\nultimate outcome is in part a product of the forces which play upon it, or\nin other words of education and training.\n\n=Gradation in Nervous Response from Lower Organisms to Man.--=To\ncomprehend fully the basic nature of human neural responses one must seek\nthe roots in the behavior of lower organisms. For there is found in a\nsimpler form many of the fundamental activities and the first dim gropings\nwhich emerge in man as memory, reason and will. As we ascend the scale of\nanimal life we find a continuous advance in neural complexity and nervous\nresponse that in many respects grades up closely to the human type.\n\nA windmill or a weather-vane points toward the source of the wind,\nobviously not because either exercises any special choice in the matter,\nbut because it is constructed on such lines of symmetry that when the wind\nstrikes it, if it slants the slightest to left or right, the more exposed\nsurface receives the greatest pressure and thus swings the body back into\nthe line of least resistance.\n\n=Behavior of Many Animals Often an Automatic Adjustment to Simple External\nAgents.--=It is a far cry, of course, from the responses of such a machine\nas a windmill to the responses of even the simplest living thing, but in\nspite of the broad gap between the two, there is much reason to believe\nthat the behavior of many living organisms is due in a marked degree to\nthe directive effects of comparatively simple external factors rather than\nto the complex internal volitions the casual observer is likely to\nattribute to them.\n\n=Tropisms.--=It is a marked characteristic of all living protoplasm that\nit has the power of responding to external stimuli. This power of response\nis termed _excitability_ or _irritability_. In describing the motor\nresponses of living organisms to stimuli resulting from a change in\nsurroundings the term _tropism_ (Gr. _Trope_, turning) is frequently used\nand the kind of stimulus is indicated by a prefix. Thus the term\nphototropism means a turning or _orientation_ brought about by means of\nlight. An organism which reacts by a movement toward the source of light\nis said to be _positively phototropic_, one which moves away from it,\n_negatively phototropic_. By using such a neutral terminology the\nphysiologist avoids implying that necessarily \"likes\" or \"dislikes\" or any\nother psychic reaction enter into the movements.\n\nSeveral kinds of tropisms are recognized, such as _phototropism_ or\n_heliotropism_, reaction to light; _thermotropism_, reaction to heat;\n_electrotropism_ or _galvanotropism_, to electric current; _geotropism_,\nto gravity; _chemotropism_, to a chemical; _rheotropism_, to current;\n_thigmotropism_ or _stereotropism_, to contact; and _chromotropism_, to\ncolor.\n\n=Many Animals Show Tropic Responses.--=Many of the lower animals seem to\nhave their movements determined more or less mechanically by the action of\nsuch external factors, some being positively, others negatively responsive\nto a given kind of stimulus, or the same individual may be at one time\npositive, at another negative, according to modifying conditions to be\nmentioned presently.\n\nIn plants and in simpler lower animals there is no special nervous system.\nThe responses of these organisms depend on the general irritability of\ntheir constituent protoplasm. In other animals a nervous system is\ndeveloped, crude and diffuse in lower forms, extremely delicate, complex\nand definitely ordered in higher forms. But it should be borne in mind\nthat nerve protoplasm possesses only in high degree a capacity for\nirritability, conduction, etc., that is common to all living substance. In\nkeeping with other \"physiological divisions of labor\" or specialization\nwhich mark the increasing complexity of animals, this enormously enhanced\nsensitivity and conductivity of certain tissues have come about, and they\nhave become set apart for these special functions. In higher animals,\ntherefore, the tropisms where operative must act more or less through the\nagency of the nervous system instead of directly through the general\nprotoplasm of the organism.\n\n=Certain Apparently Complex Volitions Probably Only Tropisms.--=Where\nnervous systems enter into tropic responses there must be specific\nsensibility of certain nerve terminations (i. e., sense organs) at the\nsurface of the body. These sensory or receiving nerves connect through the\ncentral system with corresponding motor nerves which in turn supply\ncertain specific muscles through the contraction of which the organism is\nas surely and as mechanically oriented as in the simpler cases. For\nexample, if light is the stimulating agent, when it strikes a positively\nphototropic animal, if the latter is not already oriented, the eyes or\nother nerve terminations sensitive to light transmit an impulse through\nthe central nervous system to certain muscles causing them to increase\ntheir tension and thereby swing the animal around with its head toward the\nlight. Progressive movements which the organism then makes must carry it\ntoward the source of light. Thus it is not \"love of light\" that draws the\nmoth into the flame but the mechanical steering of the body toward the\nsource of light through the stimulations produced by the light waves. It\nis chemotropism, not solicitude for its offspring, which drives the flesh\nfly to lay its eggs on decaying meat. And it is stereotropism and not a\ndesire for concealment which impels certain animals such as many worms\nand insects to get into a close contact with solid bodies, or in other\nwords to \"hide\" themselves in burrows and crevices.\n\n=Complicating Factors.--=However, beautifully as these theories of\ntropisms work out in a broad general way, there are various additional\nfactors entering which must be reckoned with, and these become more\nnumerous and of more consequence as the organism becomes more complex. In\nthe first place certain internal conditions must be considered. Living\nmatter is characterized by its instability. There are continual synthetic\nand disruptive processes in progress which the physiologist terms\nmetabolic changes. The very \"life\" of such matter seems to be the\nmanifestation of such changes. Concerning what the ultimate source of\nthese changes is, whether or not indirectly they may be referred to\nexternal conditions as seems probable to many biologists, no one so far\nhas ever given a convincing, positive answer. It is sufficient for our\npurposes to know that they may have set up certain internal stimuli which\nmay modify the behavior of the organism in which they reside, and that the\n\"physiological state\" of the organism at the time of external or internal\nstimulation will condition the response. This physiological condition may\nbe dependent on the general metabolic equilibrium of the animal, or on the\nextent of previous stimulation by means of the same or different agents.\nThus the organism may not always react in the same way to the same\nstimulus.\n\nThe intensity of the stimulation and change in the intensity of the\nstimulation, are also factors to be reckoned with. Moreover, it must be\ntaken into account that a given organism is often operating under the\ncontrol of more than one external influence. For example, swarm spores in\na dish of water which at a given temperature are positively phototropic,\nthat is, gather at the side of the dish toward the light, may, if the\ntemperature of the water is raised or in case of marine forms if the\nsalinity is increased, become negatively phototropic. Sometimes two or\nmore forms of stimuli may cooperate in bringing about certain behavior as,\nfor instance, in the reaction of the earthworm to a suitable habitat,\nthrough a combination of chemical and contact stimuli. On the other hand,\ntwo different stimuli may interfere with each other; for example, the\nusual phototropic responses of certain animals do not manifest themselves\nwhen they are mating or feeding. In short, anything that alters the\nphysiological state of the organism may cause it to react in a different\nmanner. And thus with the interplay of shifting external agents and\nvariable internal state the bounds of behavior on these purely mechanical\nbases become considerably extended.\n\n=Many Tropic Responses Apparently Purposeful.--=The query arises as to why\nif these responses are mechanical they are so often apparently purposive;\nthat is, why do they so often subserve some useful end for the animal?\nWhile they do not always work out to the animal's benefit, as for instance\nin the case of the moth and the light or under many other conditions that\ncan be devised experimentally, as a matter of fact under normal natural\nconditions they are on the whole useful to the organism, carrying it\ninto suitable surroundings of food, lessened danger, temperature, and the\nlike.\n\nThe probabilities are that in their first origin the reactions were not\npurposive. However, if any proved harmful they would result in the\nextermination of their possessors and hence of that particular strain of\nindividuals. Those types that happened to have useful reactions would be\nleft and in course of time as the process of eliminating the others went\non, would become the prevailing types. Any organism which the useful\nreaction had preserved would tend to hand it down to the succeeding\ngeneration where again it would be the conserver of those individuals\nwhich possessed it in sufficient degree.\n\n=Authorities Not Agreed on Details of Tropic Responses.--=Although all the\nforemost modern students of animal behavior accept as facts the more or\nless mechanical orienting effects of external stimuli, there is by no\nmeans unanimity of opinion regarding details. Some stress as the directive\nfactor the continuous action of the stimulating agent on sensitive tissues\nsymmetrically situated. Others would maintain that it is the time rate of\nchange in the intensity of the stimulating agent, or that the factor is\ndifferent in different cases. Some make much of an automatic sort of\n\"trial and error\" system by which certain organisms test out an inimical\nenvironment until the path of least irritation is hit upon as the way to\nsafety. The field is a broad one and to get at the finer shades of\ndistinction the reader will have to refer to the works of such\nauthorities as Loeb, Jennings, Holmes and Mast.\n\n=Tropisms Grade Into Reflex Actions and Instincts.--=The tropisms in many\ncases become indistinguishable from _reflex actions_ and these in turn\ngrade up into the _instincts_ of animals. The latter may be looked on as\nbut subtler and more involved reactions made possible through a more\nintricate structural organization. As might be expected of instincts, the\nfeature of utility is more in evidence than in simpler tropisms because\nthey have become of proportionately greater magnitude, but the same\nfundamental mechanism is apparently at bottom of both. It has already been\nseen how the \"instinct\" of the blow-fly to lay its egg on meat is\ninterpretable as a chemotropic response. Thus no elaborate psychic\nmechanism is necessary in such behavior.\n\n=Instincts.--=In the typical instinct there is a series of \"chain\nreflexes\" in which one step determines the next until mechanically the\nwhole gamut of changes is run to the last step. It is characteristic of a\npurely instinctive act that an animal performs it without practise,\nwithout instruction, and without reason. Moreover, all of the same kind of\nanimals tend to perform the act in the same way. But with instincts, as\nwith tropisms, the physiological state of the organism must be regarded.\nFor instance, the instinctive reactions of an animal sated with food or\nhungry will be different.\n\n=Adjustability of Instincts Opens the Way for Intelligent Behavior.--=As\nwe progress in the scale of animal life this adjustability of instincts\nto new conditions comes more into evidence. While prescribed in the main\nby internal impulse the carrying out of the action is capable of some\nadaptability to circumstances. And in proportion as this adaptability\nreleases the organism from a blind rigid working-out of a predetermined\nend, there is opened up the possibility of intelligent behavior; that is,\nof modification of the instinctive behavior by individually acquired\nexperience.\n\nWhile the generation of instinctive impulses still occurs it is left more\nfor individual experience to teach discrimination between ends. But we can\nnot escape a fundamental structural mechanism, for with this new capacity\nof educability must come new structural mechanisms in the nervous system\nand this must be as faithfully reproduced in each individual as is the\nbasis for any other nervous response. How low in the scale of animal life\nanimals can profit from their experiences to the extent that their future\nconduct is conditioned thereby is not known. Some would place it as far\nback as the protozoa, others would not. Where such modification of\nbehavior is possible there must be some mechanism for the storage of\nimpressions in the form of what we term _memory_.\n\n=Modification of Habits Possible in Lower Animals.--=Among invertebrates\nsuch animals as crayfish will acquire new habits, or rather will modify\nold ones. Even as lowly an organism as the starfish can have changes of\nhabit thrust on it. When a starfish is placed upon its back it rights\nitself by means of its arms or rays. Professor Jennings found that in a\ngiven individual the tendency was always to employ certain rays for this\nrather than others. However, by preventing the use of the rays customarily\nemployed, he found that the animal would use a different pair and that\nultimately in this way it could be trained into the habit of using this\npair of rays even when restrained in no way. One starfish which was given\none hundred eighty such lessons in eighteen days after an interval of\nseven days still retained the new habit; young individuals were found to\nbe more easily trained than old ones.\n\n=Some Lower Vertebrates Profit by Experience.--=Among vertebrates it is\nknown that those as low in organization as fish will profit by experience.\nThey will learn to come for food at a regular time and apparently learn\nmore or less to appreciate the presence of certain obstacles with which\nthey have had unsatisfactory experiences. Professor Sanford sums up what\nhe believes are the limitations of the piscine mental organization as\nfollows: \"No fish is ever conscious of himself; he never thinks of himself\nas doing this or that, or feeling in this way or that way. The whole\ndirection of the mind is outward. He has no language and so can not think\nin verbal terms; he never names anything; he never talks to himself; as\nHuxley says of the crayfish, he 'has nothing to say to himself or any one\nelse.' He does not reflect; he makes no generalizations. All his thinking\nis in the present and in concrete terms. He has no voluntary attention, no\nvolition in the true sense, no self-control.\"\n\n=Rational Behavior.--=Finally, however, out of these first dull\nglimmerings of intelligence as exemplified in the higher invertebrates\nand the lower vertebrates, which can modify behavior as the result of\nexperience, come the still higher factors so dominant in man, of\n_rational_ behavior. This higher mental process can realize the end to be\nreached and can deliberate on the means to be employed. By means of his\n_reason_ man can overcome difficulties in advance by \"thinking\" out\nsuitable schemes of action. Some naturalists believe that man stands alone\nin possessing the power to reason, although others believe that some of\nthe other mammals, notably the other primates, possess the same attribute\nalthough in a much less degree.\n\n=Conceptual Thought Probably an Outgrowth of Simpler Psychic States.--=Is\nthe capacity for such conceptual thought, however, which appears as the\nfinal efflorescence of complex neural activity something entirely new?\nMost students of comparative psychology maintain that it is not. Just as\none kind of an instinct frequently grows out of another, so has this grown\nout of the complex of _psychic_ states which preceded it. It apparently is\nthe product of the increasing awareness on the part of animals of their\nneural processes and the outcome of these processes, which becomes more\nand more prominent as we ascend the scale of animal life. With the advent\nof associative memory the mind comes more and more to deal with attributes\nof objects instead of merely with each single concrete object as it\npresents itself, and these attributes being common to many objects, come\nto represent definite ideas which can be manipulated by the mind.\nLanguage, of course, has been an indispensable aid to man in this regard,\nfor words become descriptions of facts and symbols of concepts, and\nthereby allow of abstract thought.\n\n=The Capacity for Alternative Action in High Animals Renders Possible More\nThan One Form of Behavior.--=With this modification of instinct by\nexperience made possible, there comes at the same time, of course, the\ncapacity for a rational instead of a purely instinctive behavior. This\nvery capacity for alternative action opens up many new possibilities of\nbehavior and together with the well-known fixative effects of habit, also\nthe opportunity of permanently establishing certain ones. Thus it is\nobvious that a behavior toward which in a strict sense there can not be\nsaid to have been an original specific tendency, can be developed. What\nwas present in the first place was only a general possibility of the\ndevelopment of any one of several types of behavior. The final choice of\nthe alternatives together with repetition makes it the habitual behavior\nof the individual. Of course it can be urged that if the selection of the\ntype of behavior is left to the individual then the latter will operate\nautomatically toward the various impulsions of its neural make-up and one\npath will be followed because of stronger inclination in that direction,\nso that the whole procedure is in the end the mere operation of an\nautomaton. But however this may be in the individual left to itself, the\nfact is in man that the young individual is never left to itself and in\nthe nature of things can not be, so that without entering into this\ntroubled pool of controversy regarding freedom of the will, I wish merely\nto point out that the possibility of more than one form of behavior\nexists and that if one is more desirable than the others then this one can\nbe chosen by the ones responsible for the training of the young individual\nand clenched fast by the agency of habit.\n\nIntelligence, reason and habits, however, no less than instincts and\ntropism must have neural as well as psychical existence and we can not\nescape therefore the underlying mechanism.\n\n=The Elemental Units of the Nervous System Are the Same in Lower and\nHigher Animals.--=It is interesting to note that the fundamental neural\nmechanism which underlies the mental processes of higher animals is not\nessentially different from that which serves in lower forms. Although as\nanimals become more complex their nervous systems have become\nproportionately larger and incomparably more intricate, still all the\nchanges have been rung on the same basic neural unit, the _neuron_ or\nnerve-cell (Fig. 32_A_, p. 209). The higher nervous system differs from\nthe lower in the number, in the specializations and in the associations of\nthese units rather than in possessing something of entirely different\nelemental structure.\n\n=Neuron Theory.--=According to the prevailing modern conception the entire\nnervous system is made up of a series of units called _neurons_. Each\nneuron is a single cell with all its processes. The latter consists\ntypically of short branching processes on the one hand, known as\n_dendrites_, and of a single process on the other, known as the _axon_,\nwhich extends from the cell to become a nerve fiber (Fig. 32, p. 209). The\nvarious neurons, with possibly a few exceptions, are not anatomically\ncontinuous but contiguous. They communicate with one another apparently by\ncontact only. The axon of each neuron ends in an elaborate series of fine\nbranchings which lie in contact with the dendrites of another neuron, or\nin some cases with the body of the other cell (Fig. 32, p. 209). Thus the\nnervous impulse passes from one neuron to the other at these points of\ncontact. An impulse is supposed to travel normally only in one direction\nthrough a neuron, the dendrites being the receiving and the axon the\ndischarging terminals. There are various types of neurons. Some,\nparticularly within the brain, have their main processes so provided with\nbranches and brushes that they may come into physiological connection with\na number of other neurons.\n\n\n[Illustration: FIG. 32\n\nA--Diagram to illustrate neurons and their method of connection; _a_,\naxon; _d_, dendrite; _s_, synapse. To simplify the diagram the medullary\nsheathes of such fibers as would have them have been omitted. The arrows\nindicate the direction in which the impulse travels. The lower series\nshows diagrammatically how from the same neuron in the cortex two\nsubordinate neurons may be affected, the one excited to cause contraction\nof a certain group of muscle fibers, the other inhibited so that the\nantagonistic fibers may relax and thus not hinder the movement of a given\npart.\n\nB--Section of a region of the cerebral cortex (after Cajal). The cells\nhave been blackened with chrome-silver and are much less highly magnified\nthan the diagrams in A. The numerals refer to certain characteristic\nlayers of the cortex in this region.]\n\n\n=Establishment of Pathways Through the Nervous System.--=It is believed\nthat more or less resistance to transmission of stimuli prevails at the\npoint of contact (_synapse_) between two neurons but that this resistance\nis lessened by repetition of conduction. The frequent traversing of a\ngiven pathway by similar impulses finally results in an automatic\noccurrence of the transmission, or, in other words, the action becomes\nhabitual. Education consists largely in establishing such routes through\nthe nervous tissue. Because of the greater plasticity of the neural\nmechanism in youth it is easier to open up and fix pathways of conduction\nthan in later years. Moreover the earlier established lines of conduction\nbecome the more permanent.\n\n=Characteristic Arrangements of Nerve Cells Are as Subject to Inheritance\nas Other Structures of the Body.--=That the main features of the nervous\nsystem are inherited becomes obvious when we see that each kind of animal\nhas its own distinctive numbers, arrangements and proportions of the\nvarious neural units. In man, for example, there are certain\ncharacteristics, types and groupings of nerve-cells which are reproduced\ngeneration after generation with remarkable fidelity. This means that in\nso far as these represent the mental make-up of the individual, his\nmentality is continuously linked with others which have gone before. The\nnew-born child has all the nerve-cells in its brain that it will ever have\nbut the ultimate linkages of the finer connectives between them, or at\nleast the pathways of travel, remain in large measure to be made.\n\nAs we have already seen, the cerebral cortex is the seat of the chief\nmental faculties of man or at least of the highest of these. Professor\nLloyd Morgan, one of our greatest authorities on comparative psychology,\nis inclined to believe that the instincts are located in the subcortical\nmaterial. In any event, the inheritance of mental ability resolves itself\ninto the inheritance of a certain cerebral mechanism.\n\n=Different Parts of the Cortex Yield Different Reactions.--=The cerebral\ncortex, however, is not functionally homogeneous throughout. Certain\nregions have been shown to be motor, others sensory, and moreover, these\nregions are apparently further specialized so that a given one of them is\nassociated with a specific type of sensory or motor response, not merely\nwith responses in general. Thus by injuring one of the sensory areas we\nmight destroy vision but not other sensations, or by stimulating one of\nthe motor centers we would get a response in a corresponding motor organ\nbut not in all such organs. Likewise, it is probable that still different\nareas, the so-called \"association areas,\" relatively of much greater\ndevelopment in man than in any other animal, are the regions in which\nvarious perceptions and conceptions are synthesized and formed into\norganized knowledge. Here also are engendered the volitions which when\nflashed through the motor centers become expressed in activity or\nbehavior.\n\nIt seems highly probable that just as the sensory and motor areas differ\nin kind from one another, so we must suppose there are qualitative\ndifferences in various parts of the association areas so that the\ndifferent parts give different reactions in consciousness; that is, each\nspecial mental ability of the individual is more or less centered in a\nspecial part of the cortex. And just as there may be variations in other\nstructures of the organism so there may be variations in these areas. The\n\"gifted\" person in some one direction, whether it be in mathematics,\nmusic, painting, or what not, is on this hypothesis one who has that\nparticular area of his brain which forms the basis for the talent in\nquestion more highly developed than it is in the average individual. And\nsince such talents are handed down to descendants, this can only mean that\na similar grouping of the neurons in the region in question has occurred.\n\n=Skill Acquired in One Special Branch of Learning Probably Not Transferred\nto Another Branch.--=Such a differential arrangement of the\nbrain-mechanism which presumably underlies the various mental abilities\nwould lead to the inference that skill in one special branch of learning,\nin so far as it involves only certain centers of the cortex, would not be\ntransferred to another branch based on different neural pathways and\ncenters. Development of historical knowledge, for example, would not\nenhance one's mathematical ability, or vice versa. The testimony of\nvarious psychologists bears out this idea. In so far as certain factors of\ntraining, such as habits of industry, concentration, etc., are common to\nthe study of either mathematics or history, the good effects of either\ndiscipline will probably be much the same, but the identity of effect\nvanishes as soon as the intrinsic characteristics of the subjects\nthemselves are involved.\n\nJust how far we are warranted, however, in carrying this idea of localized\nfunctions as regards the association areas is a moot question. Our present\nattitude regarding the specificity of such localizations is largely a\nmatter of inference based on analogy to conditions which obtain in other\nand better known parts of the brain, together with the indubitable\ndifferences in inborn abilities which exist between individuals. Some few\nbrain physiologists maintain that the whole cortex operates more or less\nas a unit in all of the higher psychical activities.\n\n=Preponderance of Cortex in Highest Animals.--=One of the most interesting\nconditions in the nervous system of the highest types of animals is the\nway in which the cortex has outrun the other parts of the brain in size\nand complexity and has come to dominate the organism more and more both\ndirectly and indirectly. Aside from the proportionately greater increase\nin size of the cortex, there is an abundance of anatomical evidence of\nthis altered and probably altering system of control in man and the higher\napes. This is well illustrated in the fiber tracts (nerve bundles) of the\nspinal cord.\n\n=More Long Fiber Tracts in the Spinal Cord of Man.--=The spinal cord\nalthough having many nerve centers of its own is also in great part a\nlarge cable for conducting enormous numbers of fibers from one part of the\ncord to another, or to and from the brain. In man and the higher apes a\nconsiderably larger percentage of the total area of the cord is given up\nto the long fiber tracts from the brain to the body than in lower\nvertebrates. This progressive increase in long fiber tracts in the higher\nanthropoids probably marks more and more domination of the body by the\nhigher brain centers and correspondingly less by the direct activity of\nthe cord and by the lower brain centers. However, even in man, many of the\nsimpler reflexes of the body still have their centers in the spinal cord.\n\n=Special Fiber Tracts in the Cord of Man and Higher Apes.--=There are\ncertain special tracts of the cord that are particularly interesting in\nconnection with the increasing domination of the brain over the body,\nnamely, the _pyramidal tracts_. These were the latest tracts to appear in\nthe animal kingdom and are apparently the latest to become functional in\nthe individual. It is believed that the development of the medullary\nsubstance (an enveloping sheath) of the common medullated nerve fiber\nmarks the time of entrance of the fiber into activity and it is a\nsignificant fact that the formation of this sheath occurs last of all in\nthe fibers of the pyramidal tracts, where it does not appear till after\nbirth. These tracts convey impulses from the brain to the body. They\nconsist of two sets of tracts, in fact, one the crossed, the other the\ndirect. As an anomaly, probably arising most frequently from instrumental\ninjury at birth, the pyramidal tracts fail to develop normally, with the\ndistressing result that the infant, although possessing perfectly normal\nbrain activity and normal spinal cord reflexes, is unable to exercise\nvoluntary control of the body. In other words the condition, like\nhare-lip, is one of suppressed development. At least this seems to be the\nmost plausible explanation of what is known as _Little's disease_. Such\nunfortunates usually die early although they may survive for a few years.\n\nThe direct pyramidal tracts occur only in man and man-like apes. They vary\nconsiderably in extent in different individuals. They originate in nests\nof characteristic large cells located in the cerebral cortex and are\nregarded as paths, though not the only ones, through which volitional\nimpulses are conveyed from the brain. They seem to control certain of the\nfiner and more delicate movements of the body.\n\n=Great Complexity in Associations and More Neurons in the Brain of Man\nThan of Other Animals.--=It has already been noted that as animals stand\nhigher in the scale of life while the general plan of their neural\nelements remain the same, there is increasing complexity in the number and\nconnections of the neurons. The number of processes on individual\nnerve-cells is also greater. There is in fact much greater complexity in\nthe number of processes and the inter-connections of the neural cells\nthan in the numbers of the cells themselves. This would seem to indicate\nthat the greater mental activities of higher animals depend more on\nrichness in complex associations than on mere increase in number of\nneurons. The latter, however, is by no means unimportant as may be seen in\nman, for instance, in whom it is estimated that the cerebral cortex, that\nis, that part of his brain in which his more complex mental processes\ntranspire, contains some nine billion more nerve cells than does the\ncorresponding region of the brain of an anthropoid ape.\n\nOf especial significance in the psychic make-up of man is his vastly\nincreased capacity for inhibition. Although not possessed by all men in\nequal measure and not entirely wanting in lower animals it is a\ndistinctive feature in all human conduct. Much of any child's education,\nparticularly as it pertains to behavior, must be concerned with training\nin the exercise of proper inhibitions. He must learn to suppress certain\nprimitive types of reaction in favor of higher ones. This applies not only\nto motor activities but to trains of thought as well. The essence of\nself-control consists mainly in ability to substitute for one impulse or\nidea other compensating ones. And the secret of concentration lies in\nbeing able to banish irrelevant ideas and focus on the central thought.\n\n=The Nervous System in the Main Already Staged at the Time of Birth for\nthe Part It Must Play.--=It is clear from what is known of its anatomy\nthat in the main the central nervous system is framed to respond in\ncertain set ways, that there are determinative elements in it which\ncontrol or determine the responses, and therefore the behavior of the\nbody. The same evidence shows also, however, in the incompleteness of many\nof the associations, that while the stage is all set and some of the main\nfeatures of the performance are determined at the time of birth,\nconsiderable yet remains to be done toward fitting the parts together and\nworking up the detail. Just exactly what and how much is rigidly\ndetermined no one knows.\n\n=Many Pathways of Conduction Not Established at Birth.--=As we have\nalready seen the evidence is that many of the neural pathways are not yet\nfully established at birth, and there is some indication that routes once\nopened may be altered. To what degree this has bearing on behavior is\nstill unknown, but since neurologists attribute so much importance to the\nrichness and the associations of the cell-outgrowths, it is evident that\nthis increase in the number of pathways after birth with possible\nalternatives of connections may be a very important factor in the\nmodification of behavior. Yet, on the other hand, we are completely in the\ndark as to what extent these later associations are predetermined in the\nearlier cells.\n\n=The Extent of the Zone That Can Be Modified Is Unknown.--=There is little\ndoubt that many of the paths of action are already firmly established.\nOthers, although not irrevocably fixed, offer the least resistance and\nwould \"naturally\" be taken if not counteracted or modified by the more or\nless artificial development and fixation of other paths through\ncultivation and habit. Yet others perhaps are largely neutral; they still\nawait the initial decisive push which \"choice\" or external environment may\nmete out to them. As trainers of youth all that is left that we can do is\nto attempt to develop in certain ways the elements of this indefinite,\nimpressible zone. Unfortunately, we must labor in the dark to a great\nextent as we have all too little indication of which the malleable factors\nof intellect and conduct are. We can only infer from long, intelligent and\nsympathetic observation of children in successive stages of their\ndevelopment. It is only by having clearly in mind the nature of our\nproblem that our conclusions will finally come to be of enhanced practical\nvalue in the training of children. Observation to the present time clearly\nindicates that many children are strongly predisposed this way or that \"as\nthe sparks fly upward.\"\n\nThis is a point too frequently overlooked by educators. They are often\nunduly actuated by the other piece of the truth that, \"as the twig is bent\nthe tree inclines.\" They sometimes fail to realize that after all the tree\nremains the same kind of a tree. If an apple tree, while it may be bent\nfrom the normal path of development, it can not produce other fruit than\napples. Just how much the destiny of man can be influenced by training and\nthe exercise of his own will power is the fundamental question not only of\npedagogy but of ethics as well. For if man's rational judgments are\nmarkedly conditioned by his neural make-up then the volitional judgments\nwhich underlie conduct are likewise conditioned since they are\ninextricably intermingled with his reason. We must believe that to a\nconsiderable extent emotional expression, as well as other mental\nfunctions, is due to hereditary dispositions of the neurons in the\nvarious parts of the brain.\n\n=Various Possibilities of Reaction in the Child.--=Despite the innate\npredeterminations of the tree, it is nevertheless our province to see that\nthe twig _is_ bent, but our work can only be done with due intelligence\nwhen we recognize something of the limitations of our material. Of the\nvarious possibilities of reaction we must see that certain desirable ones\nare realized, even, in some cases, if only to have others thereby\nexcluded. It is a commonplace of psychology that all cerebral excitations,\nno matter what the origin, must vent themselves in some way and if this\nexpression is not directed into proper channels it will very likely find\nimproper ones. We must see that the young wearer of the coat of\nundetermined capacities gets it set by repeated performance into the\nhabitual wrinkles of normal social conduct. For it is a trite observation\nthat when habits are once well established it requires tremendous efforts\nto do otherwise than as they dictate. There is not the least doubt that\nsome of our subjects will respond much more readily to training in certain\ndirections of habitual reactions than others, but we have always the\nconsolatory knowledge that no matter how difficult the art may be at\nfirst, repetition reduces the difficulty.\n\nWhile much of any youth's character must be determined by external forces\nbrought to bear upon it, the ultimate climax of our effort and measure of\nour success will be the extent to which we have engendered in him the\ncapacity for initiating and carrying out through his own volition those\nimpulsions and inhibitions which tend to the highest good of humanity.\n\n=Probable Origin of Altruistic Human Conduct.--=Those phases of human\nconduct which find expression in consideration for others seem no less\nthan other mental attributes to have their origin in certain fundamental\ninstincts. Altruistic conduct, in last analysis, apparently resolves\nitself back largely to certain very fundamental impulsions, namely those\nwhich arise out of certain obligations for the welfare of others which are\nnecessarily associated with the marital, parental and filial relations\nthat must exist where the young require post-natal care. Looked at from\nthe standpoint of natural selection, this would come about as a mere\nmatter of survival value. Where the young, as in man, are helpless for a\nlong period of time, more opportunity would be afforded for the\ndevelopment of both conjugal and filial affection. The sympathetic\nemotions once established in such family relations would partly through\nhabit, partly through community of interest, readily become extended to\nclan or tribe and as a final consummation to all mankind.\n\n=Training in Motive Necessary.--=In the training of children, then, we\nmust recognize first of all that there are decided inclinations or bents\nwhich, as long as they are not anti-social in nature, must be respected if\nnot always encouraged. While it is necessary to utilize these as much as\npossible in their training still we must bear in mind that although it is\nnatural for a child to follow certain interests, the fact remains that as\nregards social worth these natural interests may not be the most valuable.\nWhen this is true we must strive to develop others which will compel\nattention and thus become impelling factors in conduct. Where certain\nfundamental impulsions run contrary to the common welfare it is necessary\nto practise the child in the setting up of inhibitions or counter-impulses\nuntil this becomes habitual. He must be led to construct a protective\nmantle of appropriate scruples, doubts and fears. It is all important to\nget the proper motives for action to prevail in his mind.\n\n=Actual Practise in Carrying Out Projects Is All Important.--=But on the\nother hand it is equally important to see that the action is effectively\ncarried out. In the matter of self-discipline, particularly, we may have\nmany ideal impulses and realize that they should prevail over certain of\nour natural propensities, but unless we put forth effort to overcome the\npropensities our ideal impulses are of no avail. The world has many such\nmoral paralytics to-day who can not seize their \"languor as it were a\ncurling snake and cast it off.\" It is training in this very overcoming of\nreluctance, in this putting forth of actual effort toward worthy ends\ninstead of merely memorizing precepts about the desirability of such\naccomplishments, that is so sadly lacking in our school and home life\nto-day. We prate of the importance of self-control, we say with our lips\nthat the way to learn to do is by doing, we proclaim that it is more vital\nto instil good mental and physical habits into our pupils than to stock\nthem with information, we preach that mere fact training is as conducive\nto making a first-class rascal as an upright man, yet we jog on\ncomplacently in the well-beaten ruts of memory routine which require the\nmemorizing of symbols rather than real understanding. We seldom require\nthat our proteges make intelligent judgments based on evidence, we rarely\nexact of them decisions in matters of ethics, and almost never demand that\nthey put their knowledge into efficient accomplishment. It can not be too\nstrongly urged that we need less of formulae learned by heart, less dead\nerudition pigeonholed in the brain like so many foreign bodies, and vastly\nmore assimilation of knowledge into the living personality of the\nindividual.\n\nWhere in school or home to-day do we find provision for such training? Our\ntendency is, in fact, just the opposite. According to the modern code, as\nit works out in many instances at least, the child must be taught through\nplay. Though it is a truism that he who has not learned obedience can\nnever be master of himself, the child of to-day must not be made to obey\nbut be wheedled into changing his mind. If a given subject of study proves\ndistasteful to him, the fault is the teacher's for not making it\ninteresting, for he must always be led on by the thrill of fascination. In\nother words, the child must not only be allowed but be encouraged to take\nthe path of least resistance. His own pleasure is to be the standard of\nhis actions. Let no stern demands of duty interfere!\n\nIs it any wonder that the products of such tutelage come into the\nactivities of life self-indulgent and undisciplined, and although often\nrecognizing our private and public shame in business, politics and\nconduct, still remain supine, evasive of the unpleasantness or hardships\nof reform, or inefficient or unwilling in accomplishing unselfish ends?\n\n=Interest and Difficulty Both Essential.--=The writer does not wish to be\nunderstood as minimizing the importance of interest on the part of the\nchild in what he is doing. Interest is undeniably the open sesame to\ndesirable mental development; but what he does protest against is that not\nuncommon interpretation of interest which deems it necessary to eschew\nmost serious consideration of a subject and evade such parts as present\ndifficulties. Certainly if there is any fact that stands out prominently\nin human experience it is the fact that nothing conduces to the\ndevelopment of moral stamina so much as the overcoming of difficulties,\nparticularly distasteful difficulties.\n\n=Conduct Developed Through Actual Performance.--=Self-control and the will\nto do can be trained and crystallized into habit as well as can any other\nactivity. It is a fact that one well grounded in morals by habit will\nsuccessfully resist subconscious impulsions to wrongdoing even when\nsuggested in the hypnotic state. Conduct is largely a matter of growth\nthrough actual performance. For proper guidance of this growth there must,\nof course, be high ideals around which the feelings are led to cluster and\nby which they gradually come to be controlled.\n\n=Construction of Ideals.--=The construction of such ideals through\nexample, through precept, through appeal and through actual practise in\nself-denial and self-control on the part of the child, should be the\nforemost duty of the parent or teacher. Above all it should be remembered\nthat imitation of teacher, of parents, of companions, is more of a factor\nthan intellect in the moral action of children. At present educationally\nwe are in a fever for vocational training, for \"practical\" work, and in\ngeneral for all things conducive to coaching our pupils in how to make a\nliving, yet commendable as all this may be, is it not of even more\nfundamental importance to train them how to live?\n\n=The Realization of Certain Possibilities of the Germ Rather Than Others\nIs Subject to Control.--=It may be said in a sense that there exists\npotentially in any germ all the things that can possibly come out of it\nunder any obtainable conditions of environment. The very initiation of a\ngiven mode of expression by some environmental factor, however, often\nmutually excludes many of the others. We get a given average result\nordinarily because development normally takes place in a given average\nenvironment.\n\nAs may be easily shown by experiment, this is manifest even in the\ninstincts of lower animals. In the young the various instincts do not come\ninto expression at the same time, and it not infrequently happens that if\none of the earlier instincts becomes operative toward certain objects or\nsituations, later instincts will have a wholly different relation toward\nthese objects or situations than they would otherwise have had. As a\nresult the whole life conduct of the animal is markedly modified. For\nexample, young animals immediately after birth have no instinct of fear.\nThey do, however, have a strong instinct to attach themselves to some\nmoving thing and follow it. The utility of such an instinct, as for\ninstance in the case of young chickens, is obvious. The object of\nattachment is usually the parent, but man may take the place of a parent\nand the young animal will fearlessly follow him about. However if the\nyoung animal has had no experience with man during its earliest infancy a\nlater instinct, that of fear or wildness, will have come into play and it\nwill flee from him. It is clear, therefore, that by familiarizing the\nyoung animal with man before its instinct of fear has come to expression,\ncertain habitual reactions are set up in it which inhibit or limit the\napplication of its instinct of wildness as regards man. In other words,\nthe whole course of its life has been altered by this simple experience.\nThe same principle applies in even greater degree to the young of man.\n\nWe have seen in a former chapter that what in the ordinary course of\nnature was \"predestined\" to become one individual nevertheless contained\nthe possibility of becoming four or more if the environing conditions were\nmade such as to bring about a separation of the cleavage blastomeres. Or a\nfish egg that contained the possibility of becoming a normal two-eyed form\nalso contained the possibility of becoming a one-eyed form and could be\nmade to do so by certain unusual modifications of the conditions under\nwhich it develops. However we must not be led so far by the plausibility\nof this comparison that we are misled, for the fact is that we are not\ncreating anything new by these environmental upheavals, but are mainly\naltering features that already exist. Beyond doubt the nature of the\nmaterial is of greater import in the specificity of the outcome than are\nthe external forces brought to play on it. The only point I wish to make\nis that even what seem ordinarily to be predestined ends can be altered\nby environment, and that the probabilities are that certain features are\nrelatively indifferent at their inception, the environmental factor adding\nthe final touch of specificity. And our common experience in education\nwould indicate that the same is true of mental conditions, including\nbehavior. The actual appearance of a particular trait is not necessarily\nalways a matter of an initial trend, but may be due merely to the fact\nthat its development is possible under certain conditions of environment\nand that these conditions have prevailed in the given instance. And even\nwhere there is a specific bent it may be arrested through the awakening of\na contrary impulse, or, on the other hand, its exercise may prevent the\nengendering of the opposite impulse.\n\n=Our Duty to Afford the Opportunity and Provide the Proper Stimuli for the\nDevelopment of Good Traits.--=It is clearly our duty to see that the\nexpression of good traits is made possible. We must throw a sheltering\nscreen of social environment around the young individual which will fend\noff wrong forms of incitement and chances for harmful expression, and we\nmust provide proper stimuli and afford opportunity for development of\nproper modes of expression. We must not forget that a normal instinct\ndenied a legitimate outlet will not infrequently find an illegitimate one.\nAbove all we must not forget the vital importance of establishing correct\nhabits nor the possibility of even replacing undesirable ones by good\nones. If training can redirect the machine-like behavior of as lowly a\ncreature as the starfish into new courses, why should we be so willing as\nsome of our genetists would seem to be to throw up our hands and admit\nfailure in the case of man before we have even made a rational attempt to\ncorrect the evils in question? Even in lowly organisms we have seen that\nbehavior is not only the result of an innate constitution but also of the\ndegree and kind of stimulations to which it has been subjected.\n\nIf the individual himself has not the initiative or will to make the\nattempt to set up proper or corrective habits, or to cultivate the\nnecessary specific inhibitors, then all the more is it our duty to see\nthat he is led by suggestion and drill into the proper routine of\nactivities for their establishment. For if the individual with\npropensities toward moral obliquity is to be saved to society it must be\nthrough the stereotyping effects of good habits.\n\n=Moral Responsibility.--=Beyond question different men have different\ndegrees of capacity for mental and moral training. All can not be held\nequally responsible ethically, but the lowermost limit of obligatory\nresponse to social and ethical demands necessary to rank one as within the\npale of normal conduct is at such a level that any one not an actual\ndefective can in a reasonably wholesome environment surmount it. All\nnormal men are responsible for their conduct.\n\n\n\n\nCHAPTER VIII\n\nMENTAL AND NERVOUS DEFECTS\n\n\nSome of the most important and serious problems which confront humanity\nto-day lie in the realm of mental and neural maladjustments. For human\nprogress and social welfare are in last analysis based fundamentally on\nthe results of normal reactions of human nervous systems. Any serious\nderangement of the latter may, and in certain cases must, lead to more or\nless disaster for the individual and disorder for society of which he is a\nunit. So appalling has the number of neuropathic subjects become in modern\ntimes that the matter may well cause even the most thoughtless citizen to\npause and consider.\n\n=Prevalence of Insanity.--=As to the prevalence of insanity, one learns\nfrom recent charts prepared by a member of the National Committee for\nMental Hygiene that in 1910 we had more insane (187,454) in our\ninstitutions than there were students (184,712) in all our colleges and\nuniversities in the United States, or officers and enlisted men (142,695)\nin our combined United States army, navy and marine corps; further, the\nyearly cost ($32,804,450) of caring for these insane is greater than the\nannual cost of construction ($32,520,100) on such a stupendous undertaking\nas the Panama Canal. In New York over twenty per cent. of the revenues of\nthe state go to support the insane. Doctor Lewellys F. Barker, President\nof the National Committee for Mental Hygiene, says: \"It is calculated that\nsome 250,000 people in the United States are insane. One of every five men\ndischarged from the United States army for disability is discharged\nbecause of insanity, 60 per cent. of the cases being _dementia precox_.\"\n\nEven in individual states with exceptionally large university populations\nwe still find these outnumbered by those of the insane. Thus in Wisconsin\nby 1914 the state university had attained a population of about 4,700\nstudents resident at the university during the regular school year, and of\napproximately 6,000 attending during some part of the year, but the number\nof insane under restraint in public institutions in the state June 20,\n1912, was 6,851, with an additional 1,284 on parole. This does not include\nthe insane in various private sanatoria, and moreover a considerable\ngreater number of patients had been treated in these public institutions\nthan were resident there June twentieth.\n\nTo make such comparisons complete one should, of course, know the average\nlength of residence of students in college, and of insane patients in\ninstitutions. No accurate data on this point are at hand. The average\nperiod of residence in hospitals for the acutely insane is doubtless\nconsiderably shorter than the average period of attendance of students in\ncollege, while on the other hand the average period of residence of\ninmates in asylums for chronic insane is probably considerably longer. For\nexample, the Wisconsin State Hospital for the Insane reports a total of\n1,224 patients under treatment, but an average population at any one time\nof only 622 during the year 1911, and the Northern Hospital for the\nInsane, a total of 1,194, with a daily average of 613 during the same\nperiod. The combined thirty-four county asylums in Wisconsin, for chronic\ninsane, had a total population of 5,384 during the year 1911, with a loss\nof 517, or approximately 10 per cent. During 1912 the figures for these\nsame institutions run 5,758 and 742 respectively, or a loss of over 12.5\nper cent. The conditions in other states are probably much the same.\n\nIn other representative states we find the number of insane in public\ninstitutions as follows: California, 7,909; Michigan, 7,703; Minnesota,\n5,329; Pennsylvania, 16,992. Epileptics are estimated by alienists to be\nabout equal in number to the insane, feeble-minded to be more numerous.\nThe estimate that in the United States there are 300,000 feeble-minded is\nprobably a minimal figure.\n\n=Imperfect Adjustments of the Brain Mechanism Often Inheritable.--=The\noutside layer or \"cortex\" of the brain is the region in which the more\ncomplicated adjustments occur, especially such as pertain to human\nbehavior, and inasmuch as this portion of the brain is extremely complex\nand delicate in its mechanism, it is peculiarly liable to derangements\nwhich, even when slight, may have far-reaching effects.\n\nThis brain-mechanism is as much a product of ancestry as is any other\nstructure of the body, and it is obvious therefore that imperfect\nadjustments of its structure must be as subject to the laws of\ninheritance as are other malformations of the body. And just as with\nother defects, mental disorders may thus flow from pre-existing ancestral\nmaladjustment of the nervous system or from immediate causes thrust upon\nit, such as syphilis, alcoholism, degeneration of the blood vessels and\ntraumata. Or, in other words, the mechanism of mentality may be faulty\nfrom the beginning, or it may be made faulty by bad environmental\nconditions.\n\nThe records of the inheritance of insanity, imbecility, feeble-mindedness\nand other forms of nervous and mental defects are truly startling. Active\nresearches in this field have been in progress now for several years, and\nas each new set of investigations comes in the tale is always the same. It\nis questionable if there is a single genuine case on record where a normal\nchild has been born from a union of two imbeciles. Yet the universal\ntendency is for defective to mate with defective. Davenport gives a list\nof examples, beginning with such a one as this: \"A feeble-minded man of\nthirty-eight has a delicate wife who in twenty years has borne him\nnineteen defective children.\" Little wonder, in the light of such facts as\nthese, that the number of degenerates is rapidly increasing in what are\ncalled civilized countries.\n\n=Many Mental Defectives Married.--=But, it may be urged, these are\nexceptional cases, there is surely no considerable number of mental\ndefectives who are married. Let us look at the available facts. In Great\nBritain in 1901, of 60,000 known feeble-minded, imbeciles and idiots,\n19,000 were married, and in the same year, of 117,000 lunatics, 47,000\nwere married; that is, a sum-total of 66,000 mentally defective\nindividuals were legally multiplying, or had had the opportunity to\nmultiply their kind, to say nothing of the unmarried who were known to\nhave produced children.\n\nIn the state of Wisconsin I note from the tenth biennial report of the\nBoard of Control that of 574 patients admitted to the Northern Hospital\nfor the Insane during the year from July 1, 1908, to June 30, 1909, 274\nwere married and 29 others were known to have been married; this is a\ntotal of 303 out of 574, considerably over half. At the Wisconsin State\nHospital for the Insane we find the conditions are no better, for out of\n499 admitted in the year 1909-10, 208 were married and 65 others had at\nsome time been married, or a total of 273 out of 499. There is every\nreason to believe that conditions are approximately similar in other\nstates.\n\n=Disproportionate Increase in the Number of Mental Defectives.--=Writing\nof conditions in England the Commissioners in Lunacy state in their\nfifty-fourth report that now (1901) there is one officially known lunatic\nto 301.32 individuals of population, whereas in 1859 there was only one to\n536 individuals of population. In Great Britain, taking into account\nmental defectives of all kinds, the 1901 census showed a total of 485,507,\nor 1:85 of total population. Rentoul estimates that 1:50 would be nearer\nthe truth because of the fact that the number of officially known mental\ndefectives is much less than the actual number. The conditions in Ireland\nare even more impressive, for in 1851 there was one known lunatic to 657\nindividuals of population; in 1871, one to 328, and in 1901 one to 178.\nWhen all allowance is made in these statistics for the greater accuracy of\nrecent enumeration, and for other modifying influences, such as migration,\nwe are still forced to believe that an alarming increase in insanity is in\nprogress and that society is woefully derelict in permitting the marriage\nof such unfortunates.\n\nA census of the insane under public care in Wisconsin June 30, 1910, not\ncounting the paroled, shows 6,537, or one to each 357 of population, since\nthe population of the state was then 2,333,860. If, however, we should add\nthe number of insane in private sanatoria and the number unconfined the\nproportion of normal individuals would be very much reduced.\n\nIn the United States as a whole, while I know of no data giving the number\nof married insane, it is estimated that at least one-fourth of the insane\nare not in asylums or hospitals. In all states the number of insane in\nstate institutions (there are no available records of most private\ninstitutions) is rapidly increasing. According to the special census of\n1903 covering a period of fourteen years, during which the general\npopulation increased thirty per cent., the number of insane in\ninstitutions increased one hundred per cent. This is due doubtless in part\nto the fact that because of better facilities for keeping them a\nproportionately greater number of insane are being sent to state hospitals\nthan in former years. Moreover, improved sanitation has cut down the\ndeath-rate in asylums. The increase is in such vastly greater proportion\nthan the increase in general population, however, that it seems impossible\nto attribute it wholly to the greater accuracy of recent enumerations and\nthe increasing custom of confining the insane in asylums. This is a matter\nthat demands our gravest attention and one that should be investigated\nwith the greatest thoroughness. One of the most disquieting facts in the\nsituation in most states is that many patients--an average of\napproximately one thousand a year, in Wisconsin for example--are on parole\nsubject to recall. This means that although it is recognized that these\npatients are likely to have to be returned to the asylum or hospital,\nlittle or no restraint in the meantime is placed on their marital\nrelations.[8]\n\n=Protests Voiced by Alienists.--=Is it any wonder under the circumstances\nthat we find Doctor Charles Gorst, superintendent at the Mendota Hospital,\nvoicing in his 1910 report the following vigorous protest--and certainly\nsuch men as he are in the best position to know. He says: \"No one doubts\nfor a moment that defective mental conditions are transmitted from parent\nto child as surely as the physical defects and deformities. Every one\nknows that it is common for defectives to be attracted to each other and\nmarry, and that the defects of both parents are liable to be transmitted\nto the children. It is also true that there are more children born in such\nfamilies; and for that reason the percentage of defectives is continually\non the increase. The report of the state of Illinois shows the increase to\nbe alarming, and many other states are no better. It is absolutely wicked\nthat the persons suffering from periodical insanity should be allowed to\nreturn to their homes to propagate and scatter their children about the\nstate as dependents.\"\n\n=Examples of Hereditary Feeble-Mindedness.--=No one can look at the\nremarkable series of charts and records brought together by Doctor Goddard\nof the institution at Vineland, New Jersey, and by other directors of\nsimilar institutions, and doubt for an instant the inheritability of\nfeeble-mindedness and allied defects. In some instances the family history\nhas been followed back as far as five generations, and it is always the\nsame dire sequence of insanity, idiocy, epilepsy or feeble-mindedness,\nfrom generation to generation. For example, Fig. 33, p. 236, is one of\nDoctor Goddard's charts. It shows thirteen descendants of a supposedly\nnormal father (possibly a carrier) and a feeble-minded mother, of whom\nseven were feeble-minded, the others dying in infancy. The mother herself\nwas one of seven feeble-minded children, who were in turn the descendants\nof feeble-minded parents, of whom the woman had five feeble-minded\nbrothers and sisters. In Fig. 34, p. 237, he shows mental defects running\nthrough four generations. Fig. 35, p. 238, is a remarkable exhibit which,\nstarting in the fifth generation back with a feeble-minded, alcoholic\nman--the mental condition of his wife being unknown--shows that in every\ngeneration down to and including the present there has been nothing but\nfeeble-minded (or worse) offspring, leaving out of account two unknown\nand a number who died in infancy without revealing their mental condition.\nThis is true notwithstanding the fact that in the course of the various\ngenerations there had been several matings with apparently normal\nindividuals. The new blood, however, instead of redeeming the tainted\nstock, itself became vitiated. The numerous specific cases of inheritance\nof family traits reviewed in recent books or in special reports of trained\nworkers give us abundant confirmatory evidence of the inevitable\ninheritance of various nervous and mental defects.\n\n\n[Illustration: FIG. 33\n\nInheritance of feeble-mindedness (after Goddard): squares represent males,\ncircles females; F, feeble-minded; N, normal; E, epileptic; I, insane; C,\ncriminal; T, tuberculous; d. inf., died in infancy; the hand shows the\nindividual from whom the record was traced back; small black circle\nindicates miscarriage.]\n\n\n=Difficult to Secure Accurate Data.--=It is obvious, of course, that in\ntabulations such as these there may lurk considerable margins of error.\nNotwithstanding our Binet-Simon and other tests for feeble-mindedness, for\nexample, there is yet much to be desired in the way of accuracy. Many\ncases just bordering normality are by no means easy to decide. Then again\nin most human records, when one gets back beyond the third or, at most,\nthe fourth generation, the investigator has to depend on the hearsay\nevidence of relatives, friends or neighbors, and how vague this generally\nis can only be appreciated by those who have themselves tried to collect\nsuch data. But in spite of all the difficulties, there is little doubt\nthat the more carefully prepared records are sufficiently accurate to\nestablish the fact beyond dispute that defective tends in large measure to\nbreed defective.\n\n\n[Illustration: FIG. 34\n\nInheritance of feeble-mindedness (after Goddard); symbols same as in Fig.\n33, p. 236.]\n\n\nOne serious drawback in making a study of the inheritability of insanity\nand other nervous disorders is that so far we have dealt mainly with mass\neffects rather than specific neuroses. But even when the latter is\nattempted we are confronted by the fact that there are various\nintergradations of the recognized types of defect, that because of\nvarying degrees of defect in the same type a standard is hard to\nestablish, and above all that what appears as a specific mental malady in\none individual may crop out in his descendants in an entirely different\nguise. Moreover, not only the predisposition of the individual, but age\nand precipitative cause enter as factors in determining the ultimate\nsymptoms.\n\n\n[Illustration: FIG. 35\n\nInheritance of feeble-mindedness (after Goddard); symbols same as in Fig.\n33, p. 236.]\n\n\n=Feeble-Mindedness and Insanity Not the Same.--=Authorities make a sharp\ndistinction between insanities on the one hand and feeble-mindedness on\nthe other. According to Goddard, not only is there no close relationship\nbetween the two conditions, but in reality they stand at opposite ends of\nthe psychical scale. In general, insanity is a degenerative process,\nwhereas feeble-mindedness is an arrest of development. In the first case\nthe victim loses part of the mentality he once had, in the second he stops\nshort of normal development.\n\n=Many Types of Insanity.--=The commonest manifestations of insanity are\nundue depression, apathy, excitement, instability, obsessions,\nhallucinations and delusions. Some mental disorders are associated with\nrecognizable structural changes in the nervous system, but the structural\nbasis of many is not known.\n\nIn general there is more doubt about the inheritability of some of the\ninsanities than about cases of mental deficiency. The term insanity is\nmerely a loose descriptive one, and we shall gain little definite\nknowledge about the inheritance of such maladies until we study each\nseparate insane diathesis specifically. Psychiatrists recognize many\ndifferent forms of insanity, some of them very distinct from others and\nthe product of unrelated underlying causes. Often it is only a question of\ndegree or sometimes a matter of chance as to whether a given individual is\ncertified as insane or not. A neuropathic person who manifests certain\nanti-social activities is sure to be classed as insane, whereas another\nindividual with the same diathesis in a less degree might pass\nunrecognized. It is almost impossible in some instances to tell just where\nthe border-line between a neuropathic and a normal constitution lies. Many\nof the idiosyncrasies of the insane, indeed, are merely exaggerations of\ncharacteristics seen in normal people. Recent studies of the psychology of\nthe insane show that most of their hallucinations and delusions are\nclosely related to some previous mental experience they had before\nbecoming insane. And it has been found that the surest means toward\nremoving the obsessions of the patient in curable cases is to ferret out\nthese earlier experiences and correct the wrong impressions regarding\nthem. Again, certain forms of insanity do not become manifest except as\nspecial reactions to particular environmental conditions, and if these\nconditions do not happen to occur, then the neuropathic constitution\nthough existing would not be revealed. Certain critical periods of life\nsuch as puberty, pregnancy and the close of sexual life are particularly\nlikely to test out the mentally unstable, although such individuals may\nhave maintained normal mental balance up to the crisis in question.\n\n=Not All Insanities of the Same Eugenical Significance.--=Of the various\nkinds of insanity some seem to be of much greater eugenical significance\nthan others, not only because they are strongly heritable, but also\nbecause of the periodicity of the attacks. The patient may be repeatedly\nin and out of the asylum and in his sane intervals wholly unrestrained as\nfar as propagating his kind is concerned. _Manic depressive_ psychoses and\n_dementia precox_ in the order named represented the largest number of\nadmissions to the Wisconsin State Hospital for the Insane in 1911 and\n1912, and both of these very frequently have a hereditary basis. Fig. 36,\na chart showing the insanity in a local family as worked out by one of my\npupils, is a good example of a recurrent type. The father (Fig. 36, p.\n241) was about eighty-two years old when the record was made. His memory\nwas poor and he could not talk connectedly, although this was possibly\nattributable to old age rather than to insanity. His brother, written to\nin Ireland, stated that to his knowledge there had never been insanity in\nhis side of the family. The mother (2) was insane at nine, again at\ntwenty-nine and again at thirty-six. In her later life she has been in the\nMendota Hospital for the Insane five times and in the County Asylum twice.\nThe eldest daughter (3) has been in the State Asylum five times and is now\nat home. The next daughter (4) spent five months in the asylum in 1885.\nAnother daughter (5) likewise spent a short period in the asylum. Two sons\n(6, 7) have each spent two periods in the asylum, and a third son (8) has\nhad an attack of insanity. The youngest child died at the age of three.\nThus of the eight adult children six have been insane at some time. The\ncases in this family seem all to be instances of manic-depressive\ninsanity.\n\n\n[Illustration: FIG. 36\n\nInheritance of insanity in the L---- family. See text for description.]\n\n\n=A Neuropathic Constitution May Express Itself Differently Under Different\nConditions.--=Some of the difficulties of getting genealogies of specific\nforms of insanity are obvious from the following quotations chosen from\nthe works of eminent psychiatrists. Kraepelin, for instance, expresses the\nopinion that: \"The psychopathic charge of a family may reveal itself not\nonly by the appearance of mental disorders but also by other forms of\nmanifestation. Here belong before all, those diverse slighter deviations\nfrom mental health which go to make up the borderland of insanity:\nnervousness, states of anxiety and compulsion, constitutional depressions,\nslight hysterical disorders and forms of feeble-mindedness, tics; also odd\ncharacters, peculiarities in mode of living, criminal tendencies, lack of\nself-control, intemperance, love of adventure, mendacity, suicide on an\ninner basis.\"\n\nFrom the volume of Church and Peterson on _Nervous and Mental Diseases_ a\nfurther confirmatory opinion may be cited: \"In determining the factor of\nheredity we must not be content with ascertaining the existence of\npsychoses in the ascendants, but must seek, by careful interrogation of\nvarious members of the family, for some of the hereditary equivalents,\nsuch as epilepsy, chorea, hysteria, neurasthenia, somnambulism, migraine,\norganic diseases of the central nervous system, criminal tendencies,\neccentricities of character, drunkenness, etc., for these equivalents are\ninterchangeable from one generation to another, and are simply evidence of\ninstability of the nervous system. It is the unstable nervous organization\nthat is inherited, not a particular neurosis or psychosis, and it must be\nour aim in the investigation of the progenitors to discover the evidence\nof this.\"\n\n=Certain Forms of Insanity, But Not All, Seem to Behave as Mendelian\nRecessives.--=A number of psychiatrists and investigators of the\ninheritance of insanities (Rudin, Lunborg, Davenport, Rosanoff, Jolly),\nalthough working independently and in different countries, concur in the\nopinion that manic-depressive insanity, dementia precox and allied\npsychopathic conditions tend to occur after the manner of a Mendelian\nrecessive. On the other hand such maladies as Huntington's chorea are\ntransmitted as a dominant and in all probability at least half of the\nchildren of an afflicted individual will inherit and manifest the defect.\nAs to inheritance of various other psychoses we have too few accurately\ncharted pedigrees for most types to make very positive statements about\ntheir degree or manner of inheritance. Little can be said beyond the\nstatement that there is a decided tendency for various forms to recur in\noffspring. Where more than one case of insanity occurs in a given family\nor stock it is strong presumptive evidence that a hereditary defect is at\nthe bottom of it. As Doctor Wilmarth says, \"Mental accident may occur in\nany family, but it is rarely a second case occurs unless there is a\ntendency to nerve degeneracy.\" For example, of 818 insane at the Wisconsin\nState Hospital for the Insane during the biennium 1909-10, 187, or\npractically one-fourth were positively known to have insane relatives. Of\nthese, 24 had insane fathers, 31 insane mothers, 30 insane brothers, 23\ninsane sisters, 25 insane uncles, 21 insane aunts, and 21 insane cousins.\nWhere definite information could be obtained it was found that of the\n5,700 admissions of insane patients to the New York state hospitals\nduring the year ending September 30, 1911, 27.7 per cent. of the cases\nshowed a history of insanity in the family and an additional 22.9 per\ncent. showed a history of alcoholism, nervous diseases and the like.\n\n=Grades of Feeble-Mindedness.--=As to the various grades of\nfeeble-mindedness, while no sharp lines of demarcation can be drawn, a\nrough and ready test usually applied is the relative ability of such\nsubnormal individuals to take care of themselves. In all, the conditions\nexist from birth or shortly after. _Idiots_ are such defective individuals\nas are unable to take care of themselves even to the matter of guarding\nagainst common physical dangers. Their mentality does not progress beyond\nthat of a two-year-old child. _Imbeciles_ can take care of themselves in\nthe cruder physical ways, but are unable to earn their living. Their\nmental age ranges from three to seven years inclusive. _Morons_, or the\n\"feeble-minded\" in a more specific usage of the term, can under proper\ndirection become more or less self-supporting but they are as a rule\nincapable of undertaking affairs which demand judgment or involve\nunrestricted competition with normal individuals. Their intelligence\nranges with that of normal children from seven to twelve years of age. The\nlast class grades up insensibly into the shiftless, ne'er-do-well types\nwhich exist in every community. It is the hordes of the feeble-minded in\nthe restricted sense that afford our most serious problems to-day. The\nidiot and the imbecile are usually early and easily recognized and are\nkept more or less under restraint, but the higher grades of feeble-minded,\nthe so-called moron type, can be detected often only by carefully devised\ntests.\n\n=About Two-Thirds of the Feeble-Minded Have Inherited Their\nCondition.--=Concerning the various types of feeble-mindedness there is\nstrong evidence that heredity is a factor of greater magnitude than in\nmost insanities. All facts point to the conclusion that most mental\ndeficiency is strongly inheritable and that the majority of our defectives\nof this type come from degenerate stocks. Practically all specialists at\nthe heads of asylums and homes for the mentally deficient concur in the\nopinion that about two-thirds of the cases are hereditary. For example,\nDoctor Alfred Wilmarth, superintendent of the Wisconsin Home for\nFeeble-minded, says: \"My own observations, and those of others in this\ncountry and Europe, would indicate that at least two-thirds of the\nfeeble-minded have defective relatives.\"\n\nIn his study of two thousand children tested by the Binet measuring scale\nfor intelligence, Doctor Henry H. Goddard, director of the Department of\nResearch at the Training School for Feeble-minded at Vineland, N. J.,\nremarks concerning heredity of feeble-mindedness: \"But we now know that\nsixty-five per cent. of these children have inherited the condition, and\nthat if they grow up and marry they will transmit the same condition to\ntheir offspring. Indeed, we know that this class of people is increasing\nat an enormous rate in every community and unless we do something to stop\nthis great stream of bad protoplasm we shall some day be swamped in a sea\nof degeneracy.\"\n\nE. R. Johnstone, superintendent of the training school at Vineland, N.\nJ., in a recent bulletin remarks concerning feeble-minded and epileptics,\n\"We are now convinced that from sixty to eighty per cent. of the cases are\nhereditary.\"\n\nAgain, we find Doctor A. C. Rogers, superintendent of a school for\nfeeble-minded in Minnesota, saying, \"We have no survey of mentality in\nthis country except in very small areas, but probably about sixty-five per\ncent. of the feeble-minded children that we know of are feeble-minded from\nheredity; that is, they come from families in which there is much\nfeeble-mindedness, usually associated with various neuroses or psychosis.\nThere are about thirty-five per cent. approximately that are acquired\ncases. These cases develop from various things. Full development may be\nprevented during gestation, or early childhood, or early adolescence, but\nthese acquired cases are entirely distinct from the hereditary ones.\"\n\nIn a recent paper Doctor Martin W. Barr, chief physician for the\nPennsylvania Training School for Feeble-minded Children, says: \"In my\nindividual study of 4,050 cases of imbecility, I find 2,651, or 65.34 per\ncent., caused by malign heredities; and of these 1,030, or 25.43 per\ncent., are due to direct inheritance of idiocy; and 280, or 6.91 per\ncent., to insanity.\" From these figures it will be seen that Doctors Barr,\nGoddard, Wilmarth, Johnstone and Rogers all agree in their estimates;\nnamely, that two-thirds of our imbeciles are so through inheritance.\n\n=Some Results of Non-Restraint of the Feeble-minded.--=The following\nexcerpt from a paper by Doctor Barr, is a fair sample of what happens\nwhen such defective individuals are not restrained from propagating their\nkind:\n\n    \"My own study and observation alone, of over 4,000 degenerates, shows\n    such examples as: A man 38 years of age, the father of 19 defective\n    children, all living, he and his wife both under par mentally; as was\n    another couple, with 9 imbecile children; an idiot woman with 7 idiot\n    children. A forcible instance is that of a man with two daughters and\n    one illegitimate grandchild, all feeble-minded.... I could name a\n    family, one of the proudest in the land, where there are five\n    children, an aunt and two uncles, all feeble-minded.\n\n    \"Yet another, which in seven generations numbering some 138\n    individuals, records 10 still-born children (premature births), 16\n    insane, 7 imbeciles, 3 epileptics and 32 with mental peculiarities so\n    pronounced as to occasion remark. Of the 138 there remain 80\n    apparently normal, who are nevertheless hopeless slaves of a neurotic\n    heredity, direct or collateral.\n\n    \"In a study of 15 imbecile girls, 3 were recognized prostitutes, 9 had\n    each 1 illegitimate child (2 being the result of incestuous\n    intercourse with brothers); 1 had 2; 2 epileptics had, the one 3, and\n    the other 4 idiot children.\n\n    \"Four feeble-minded women had 40 illegitimate children.\n\n    \"A feeble-minded woman living in an almshouse since early childhood,\n    allowed to go out to service periodically, had given birth to six\n    illegitimate children, all inheriting her defect.\n\n    \"An imbecile drunkard is the father of three feeble-minded children.\n    The daughter, seduced before the age of sixteen, gave birth to an\n    idiot child; one son is a harmless imbecile, but the other is a moral\n    imbecile, a sexual pervert, a thief on the streets, and a pyromaniac,\n    firing in sheer wantonness a large mill property.\n\n    \"Another shows the entire family for three generations below normal.\n    Father, mother, mother's sister, and father's uncle, all imbecile.\n    Five children feeble-minded. One girl had a proposal of marriage, and\n    one boy is married to a feeble-minded girl.\n\n    \"One insane woman, whose brother and sister committed suicide, had\n    five sons. The oldest, feeble-minded, a drunkard and hobo, had one\n    son, a criminal. The second son, insane, had three imbecile children.\n    The third, an insane epileptic, had three imbecile sons, one of whom\n    was an epileptic. The fourth son was insane. The fifth, apparently\n    normal, had a morally imbecile son and an epileptic daughter.\"\n\nYet striking as is the inheritance of these maladies, Doctor Barr points\nout that of the 10,000 known cases of feeble-mindedness in Pennsylvania,\nonly 3,500 are sequestrated. This leaves a balance in that state of 6,500\ntotally irresponsible individuals to work havoc in society by producing\ntheir kind.\n\n=Inheritance Not a Factor in Some Cases of Mental Deficiency.--=On the\nother hand as our data show, there remain about one-third of the mentally\ndeficient type to be accounted for on other than a basis of heredity. As\nalready noted, some of these are doubtless the product of suppressions of\nnormal development by various extraneous factors operating before or\nshortly after birth. There is one class particularly, estimated by some\nauthorities as constituting as high as thirty per cent. of the\nfeeble-minded which is unusually puzzling. These are the so-called\nmongolians. The name is given because the features of such individuals\nbear more or less resemblance to those of some of the Mongolian races. The\ndefect does not seem to be hereditary although it is usually congenital.\nIt appears to be due to something which interferes with prenatal\ndevelopment. Whatever the conditions, whether lack of nutrition in the\nmother, alcoholic or other poisoning, the cases seem to be as hopelessly\nincurable as are the hereditary forms. From the social standpoint, of\ncourse, such individuals are in their immediate generation, as incompetent\nor as dangerous to society as those suffering from the more surely known\nhereditary forms of mental defect.\n\n=Epileptics.--=Although epileptics are not classed as imbeciles\nordinarily, as a matter of fact no sharp distinction can be drawn between\nthe two classes. Doctor Wilmarth says, \"Epilepsy and mental deficiency are\nas closely related as branches on the same tree.... Over one-half and\nperhaps two-thirds of all feeble-minded are subject to convulsive seizures\nat some period of their lives, and we are never surprised at the\nappearance of epilepsy in any feeble-minded person. On the other hand, so\nsmall a percentage of epileptics maintain normal mental actions as hardly\nto be worth consideration ... even those who retain a normal mind in the\nearly stages of the diseases almost infallibly become imperfect later.\"\nHow slight a chance the epileptic has of ever becoming normal may be\ninferred from a statement made by Doctor Frank Billings in a paper read\nbefore the Illinois State Medical Society in 1909 to the effect that \"ten\nper cent. or more can be cured by proper care.\"\n\nAccording to the estimates of \"The Committee of Fifty\" in the state of\nIllinois, who have been agitating for the establishment of a colony for\nepileptics, there are 10,000 of these unfortunates in that state. The\nconsensus of opinion of experienced workers in various states is that\nthere is about one epileptic to each three hundred fifty to five hundred\ninhabitants.\n\n=In Heredity Conditions of Feeble-Mindedness Are Probably Recessive to\nNormal Condition.--=As to the mode of inheritance of the various forms of\nfeeble-mindedness, the evidence points to such defects in the main as\nbeing recessive. However, no particular grade can be picked out and shown\nto be a pure recessive. For instance, the children of two epileptics will\nbe defective but it is impossible to predict always whether the defect\nwill appear as epilepsy or feeble-mindedness. This is doubtless due to the\nfact that mental deficiencies even of the inheritable type are not all due\nto the same specific cause, and in many cases the individual is defective\nin more than one direction. If one or more of a great number of units\nwhich are necessary for complete mental development are lacking, obviously\nmental deficiency will result. In other words, feeble-mindedness and\nallied disorders may not be definite characters, but simply evidences of\nthe fact that the nervous system has not developed all factors necessary\nfor normal mental coordination. Goddard, however, one of our best\nauthorities on the heredity of feeble-mindedness, is inclined to regard\nthe condition as a unit character, \"due either to the presence of\nsomething which acts as an inhibitor, or due to the absence of some\nstimulus which sends the normal brain on to further development.\"\n\nSupposing nervous defects finding expression in feeble-mindedness,\nepilepsy and related conditions, to act as a Mendelian recessive, then the\nmarriage of one such defective with another should yield only mentally\nenfeebled offspring. How nearly this expectation may be realized is seen\nfrom the following examples.\n\nIn an extensive study[9] of feeble-mindedness, just from the press, Doctor\nHenry H. Goddard points out that of 482 children with both parents\nfeeble-minded all but six were feeble-minded. Even the exceptions may be\napparent rather than real as there is possibility of mistake in judging\nthe condition of the parents or of the children themselves. Moreover, with\nthe feeble-minded one is not always sure of the paternity of a child, as\nis instanced by Doctor Goddard in a case quoted from Doctor Emerick in\nwhich of twelve children in a white family with both father and mother\nfeeble-minded ten were feeble-minded and two were not, but these two were\n_mulatto_ children.\n\nIn a paper by Weeks (_The Inheritance of Epilepsy_), in part an extension\nof an earlier joint paper by Davenport and Weeks, is recorded among others\na study of twenty-seven fraternities in which both parents were either\nepileptic or feeble-minded. Of the 28 progeny, 19 lived long enough to\nreveal their mental state. Of these 3 were feeble-minded, 8 epileptic and\n8, from parents who developed epilepsy late in life, were what Doctor\nWeeks terms \"tainted.\" In 15 fraternities in which one parent was\nepileptic and the other feeble-minded he found there had been 81\nconceptions. Of these 7 were too young to classify and 19 had died before\nfourteen years of age. Of the remaining 55, 28 were epileptic, 26\nfeeble-minded, and 1 insane. Again, in 9 families in which the parents\nwere both feeble-minded, of the 38 surviving offspring who were old enough\nto classify, 7 were epileptic, 29 feeble-minded, and 2 drunkards. In 5\nfamilies where one parent was insane and the other epileptic or\nfeeble-minded, 5 children died before the age of fourteen, the condition\nof 2 was unknown, 2 were epileptic, 4 feeble-minded, 1 insane, 8 tainted,\nand 7 seemingly normal. Regarding the latter Doctor Weeks says they came\nfrom two families where in one case the father's insanity seemed to be\ntraumatic and in the other alcoholic.\n\nIn a few cases where the defect in one parent has apparently been of a\ntype different from the defect of the other parent a \"normal\" child was\nproduced. That is, presumably each parent carried normality in the trait\ndefective in the other so that the child became simplex with reference to\neach defect. Davenport points out that not infrequently two deaf-mutes\nwhose defects are due to different causes may have normal children.\n\nIn general, however, the reasonable expectation is that where two\nfeeble-minded individuals marry, a very common occurrence, the children\nwill all show mental deficiency. A mating between a feeble-minded person\nand one of perfectly normal stock will apparently result in normal\nchildren although they will be carriers. There is some evidence, however,\nthat such carriers may occasionally show \"taints\" of abnormality in the\nform of migraine (nervous sick headache), alcoholism, queerness, violent\ntemper, etc. Thus according to the studies of Doctor Weeks, \"In 50 matings\nwhere at least one parent is migrainous, there were 350 conceptions, of\nwhich number enough is known of 212 to classify 55, or 26 per cent., as\nepileptic; 12, or 6 per cent., as feeble-minded, with the others tainted\nor normal. In the 131 matings where at least one parent is alcoholic,\nthere were 845 conceptions. Of the 494 classified, 151, or 31 per cent.,\nwere epileptic; 54, or 11 per cent., feeble-minded, with the balance\ntainted or normal.\" Marriage between two carriers will cause the defect to\nreappear in active form in approximately 25 per cent. of the offspring and\n50 per cent. will continue to be carriers.\n\n=Many Apparently Normal People Really Carriers of Neuropathic\nDefects.--=There is considerable evidence that many apparently normal\nindividuals of our average population are in reality carriers of some form\nof neuropathic defect, some authorities placing the proportion\nprovisionally at over thirty per cent. This being true, then it is easy to\nexplain the apparently unaccountable appearance of epilepsy,\nfeeble-mindedness, or similar defects among the children of what pass for\nnormal stocks. The probabilities are that in many cases it means simply\nthat the parents of the defective children have been carriers.\n\nAs to the contention that in preventing the propagation of the\nfeeble-minded we may be depriving the world of geniuses, Doctor Goddard\nremarks: \"It is a significant fact that in our three hundred family\nhistories totaling 11,389 individuals not a single genius has been found.\nNot only are there no geniuses but the fact can not be too strongly\nemphasized that even the people who are considered normal ... are not as a\nrule people of average intelligence....\" However, between insanity and\ngenius he finds more kindred spirit.\n\n=Tests for Mental Deficiency.--=As to tests for mental deficiency, the one\ncommonly meted out to victims in the every-day world is the\nsocial-economic one of survival in the competitions of life. The mentally\ndeficient fail. Although often unrecognized as feeble-minded they drift\nthrough life social and economical derelicts who have to be supported by\nthe community.\n\nOf laboratory tests many have been devised. While all yet leave much to be\ndesired, still through their application the majority of mental defectives\ncan be detected. Fairly accurate standards of normality have been\nestablished from which the relative degree of \"backwardness\" can be\ndetermined. We have just awakened to the importance of detecting\ndefectives early in life, hence many of our tests have been planned with\nreference to children. They are based not so much on training or conscious\nlearning as on fundamental processes which develop at certain ages in\nchildren. Another impetus toward securing adequate criteria of mental\ndeficiency has been the crying need of having some easily applied standard\nfor detecting the very large numbers of defective immigrants who are\ncontinually seeking to enter the United States.\n\nMost of the methods consist of \"performance\" tests which are planned to\ntest the powers of perception, concentration, application, ingenuity and\neducation of the subject. Previous environment, education and the\ndifficulties under which the subject may be laboring at the time of the\ntest must, of course, be taken into account. It is particularly difficult\nto get adequate tests for the immigrant which will enable one to\ndistinguish between ignorance, stupidity, fear and temporary psychic\ndepression on the one hand, and congenital mental deficiency on the other.\n\nPerhaps the most successful single set of tests for mental deficiency is\nthat known as the Binet-Simon Scale. From an examination of large numbers\nof French school children Binet constructed a scale of tests of increasing\ncomplexity accurately graded to age and previous training of the average\nnormal child. In the Binet-Simon system tests are given for each age from\nthree years to thirteen. When a child successfully passes the tests for\nhis age he is classed as normal. If he succeeds only in tests which\nnormally are those given for a child a year younger then he is backward to\nthe extent of one year. Similarly he may show by these graded tests that\nhe is backward to the extent of two years, three years and so on. If a\nchild is more than three years backward according to the test he is\nregarded as mentally defective. Various corrections and adjustments of the\noriginal scale have been worked out to allow for unevenness in mental\ndevelopment. On the whole the scheme works out satisfactorily when applied\nby one skilled in its use. The attitude of the examiner, however, is of so\ngreat importance that the tests are of less value in the hand of\ninexperienced workers. A revision of the scale to adapt it better to\nAmerican children has recently been made by Doctor Goddard.[10] Besides\nthe Binet-Simon tests various performance tests, standardized for children\nof different ages, such as Seguin's form board, Healy's pictorial\ncompletion test, Fernald's construction puzzle, the Rossolimo test, De\nSanctis test, etc., are used by different investigators. Questions\ndesigned to reveal moral tone are also employed. Doctor Howard A. Knox,\nassistant surgeon United States Public Health Service, in a recent\narticle[11] gives an interesting account of the tests applied to determine\nthe exact mentality of immigrants entering the United States together with\na brief review of various tests. A full account and discussion of the\nvarious tests for the mentally subnormal will be found in a recent\npublication by Doctor William Healy,[12] director of the Juvenile\nPsychopathic Institute, Chicago.\n\n=The Backward Child in School.--=It is only in recent times that we have\ncome to realize the seriousness of the problem which the backward child\npresents in our schools. It is of the utmost importance to discover early\nin school life which of the backward children owe their condition to\nadenoids, defective sight or hearing, poor nutrition, imperfect\ncirculation, or other remediable defects, and which are the victims of\ninnate mental deficiency. The treatment of the individual must be very\ndifferent in the two cases. In the one the condition can be cured by\nproper manipulations or other treatments; in the other it can only be\nameliorated. All school children who are two or three years below grade\nshould be rigidly inspected by the medical examiner.\n\nFrom a study of about two thousand children comprising the first five\ngrades of an entire public school system Goddard found that eighteen per\ncent. were definitely \"backward.\" Of these between two and three per cent.\nwere actually feeble-minded, the condition in the remaining fifteen per\ncent. being presumably capable of correction. Other similar surveys have\ngiven practically the same results.\n\n=The Exceptionally Able Child Likely to Be Neglected.--=However, while we\nmust not forget that it is important to recognize backward children and to\nsee that they are segregated into small groups which are not required to\ndo the full amount of work in regular time, it is equally urgent to see\nthat the unusually bright individual is also given opportunity to advance\nmore rapidly than the rank and file. Only too often the holding back of a\nchild in school leads to lack of interest and habits of mental laziness,\nand sometimes to truancy and incorrigibility. The general attempt in our\ngraded schools to keep all children close to the average is to be strongly\ncondemned.\n\n=Cost of Caring for Our Mentally Disordered.--=Doctor Charles L. Dana,\nmember of the National Committee for Mental Hygiene, estimated in 1904\nthat the actual cost of caring for feeble-minded and insane in the\nUnited States amounted to sixty million dollars, to which should be added\nthe corresponding loss in industrial activity on the part of the\nafflicted,--at least twenty million dollars more, and he figures that the\namount was increasing at the rate of four per cent. per annum. Many\ninvestigators concur in the opinion that our insane and feeble-minded\nalone cost us far above one hundred million dollars. Adding to this\neconomic burden the cost of our delinquents and criminals the total\nexpense becomes stupendous. And when we consider still further the even\ngreater burden of suffering of the unfortunates themselves and the sorrows\nof those to whom they are dear, a burden not measurable in money, the\nfeeling that something must be done to relieve the situation becomes\noverpowering.\n\n=Importance of Rigid Segregation of Feeble-Minded.--=As regards the really\nfeeble-minded little can be done beyond making them as happy as possible\nand developing the limited gifts they have been given by nature. Their\nteaching must be in the main concrete and simple. At the age of puberty it\nis imperative to see that the sexes are separated and kept under\nsufficient permanent supervision to prevent all possibility of\nprocreation. There is neither economic nor common sense in even allowing\nthe remotest chance of such occurrences as the following: \"This is the\ncase of a feeble-minded and epileptic woman who had six children by\nvarious persons while an inmate of a county poor house. One child at the\nage of eighteen died in the almshouse, two died in infancy, one was\nepileptic (the son of a man with a criminal record) and two who are now\nliving in the almshouse are feeble-minded, one being the son of a negro.\"\nAgain, we find a superintendent of an English almshouse reporting that one\nhundred and two out of one hundred and five children born there in five\nyears were feeble-minded.\n\nAs conditions are to-day every institution for the feeble-minded has a\nlong waiting list and the same is true of most asylums for the insane.\nInstead of providing the prolonged care necessary for such patients,\ninstitutions are forced to discharge many prematurely in order to make\nroom for more urgent cases.\n\n=Importance of Early Diagnosis of Insanity.--=In insanities, even when of\nhereditary origin, there is much hope in certain cases of greatly\nbenefiting the individual, though a permanent cure, or at least the\nestablishment of procreative fitness may be impossible. It is extremely\nimportant that the public realize how much can be done through early\nexamination and advice in such mental afflictions. Most of the insane who\nrecover usually do so within a few months of their first alienation, hence\nthe importance of losing no time in detecting the condition and securing\nearly treatment. It is now well known that many cases of chronic insanity\nmay be measurably improved under the care of a psychiatrist by systematic\nre-education, especially in industrial lines. But how little of this may\nbe expected at the hands of the untrained custodians who \"feed\" the\ninmates of our county almshouses, to which in many states the chronic\ninsane are entrusted, is obvious.\n\n=All Insane Should Be Passed Upon by Competent Psychiatrists.--=The\natrocious system of turning the chronic insane over to county poorhouses\nmanned by supervisors whose chief qualification for the position has not\ninfrequently been the lowness of their bid for boarding and caring for the\ninmates, can not be too strongly condemned. Incredible as it may seem, in\nsome states the court can on its own judgment send patients directly to\nthese institutions without first submitting them to the study of expert\nphysicians in the state hospital for the insane. The viciousness of such\nprocedure is evident when one realizes that often careful scrutiny on the\npart of the very best experts, extending over a considerable period of\ntime, is required before the true condition of the patient can be\ndetermined. Recently a psychiatrist of high standing, who was gathering\ndata on county asylums for a national organization, informed the writer\nthat beyond the shadow of a doubt he had come across case after case in\ncounty asylums which would have been curable under proper treatment.\n\nHere again the responsibility in last analysis must rest upon us as\ncitizens, for it is largely through our intelligent demands as voters that\nconditions will be improved and competent experts be put in charge of\ncounty asylums as well as of the state hospitals for the acutely insane.\n\n=Some Insanities Not of Hereditary Origin.--=Some alienists believe that\nself-poisoning known as _auto-intoxication_, due to improper elimination\nof poisons generated through faulty digestion or metabolism, if of long\nstanding, may be not only a contributory but a more or less direct cause\nof insanity. About twenty per cent. of insanities of men living in cities\nand about fifteen per cent. of those living in the country seem to be\ndirectly related to the intemperate use of alcohol. The corresponding\nfigures for women are seven per cent. and one per cent. respectively.\nGeneral paresis or softening of the brain is probably invariably preceded\nby syphilis. About twenty-two and five-tenths per cent. of the first\nadmissions to hospitals for the insane from city-dwelling men, and eight\nper cent. from men living in the country in the state of New York are\ncases of this kind of insanity. The corresponding figures for women are\nfive and five-tenths per cent. and two and five-tenths per cent.\nrespectively.\n\n=Importance of Heredity in Insanity Not Appreciated.--=We have already\nseen that heredity plays an important part in insanities. There can be\nlittle doubt that the tendency is to under-estimate rather than\nover-estimate its importance. Many cases said to be \"caused\" by mental\nstrain such as those occasioned by domestic infelicities, business\nreverses and the like should in all probability be fundamentally\nattributed to something far more deep-seated than the more obvious cause.\nIn many such instances there is little doubt that an inherent weakness in\nmental make-up exists which predisposes the individual toward mental\nbreakdown. This is more apparent when one recalls that there are thousands\nof other individuals who undergo equally great or greater calamities\nwithout loss of mental balance. There are well-recognized types of mental\ndisposition which later contribute to corresponding forms of insanity. In\nmany instances the final catastrophe may be averted if the \"peculiar\"\nindividual can be kept in good health and guided into right habits of\nthought. Undoubtedly certain infectious diseases, arterio sclerosis,\nvarious poisons in the blood, child-birth, and similar influences often\nenter as important contributory factors. In all cases of cure, however, we\nmust face the fact that under existing conditions these mentally restored\nindividuals are released into society without let or hindrance as regards\ntheir marital relations.\n\n\n\n\nCHAPTER IX\n\nCRIME AND DELINQUENCY\n\n\n=The Relative Importance of Heredity and Environment in This Field\nUncertain.--=The whole question of crime and delinquency is a highly\ncomplex one. Here, perhaps, more than in any other phase of race\nbetterment we find the greatest difficulty in separating the effects of\nhereditary predisposition from the results of unfavorable environment.\nWhile there is no longer a reasonable doubt about such nervous disorders\nas epilepsy, feeble-mindedness and certain forms of insanity being rooted\nlargely in ancestral taints, the degree to which crime or delinquency is\nbased on heredity is far more questionable. Every student of genetics\nknows that we may have dwarf plants because the constitution of the germ\nis of a nature to produce only such individuals, or we may have dwarfed\nplants because of adverse conditions of soil and lack of an opportunity to\nclimb or rise to their full capacity. Bateson pertinently remarks, \"The\nstick will not make the dwarf pea climb, though without it the tall can\nnever rise. Education, sanitation, and the rest are but the giving or\nwithholding of opportunity.\" The important sociological question for us to\ndetermine is which of these lowly peas of the human family are really\ndwarfs and which are dwarfed simply because the stick of opportunity on\nwhich to climb is lacking.\n\nBeyond doubt a considerable portion of crime and degeneracy is due in\nlarge measure to innate inclination, but with just as little doubt much is\nthe effect mainly of vicious habits acquired through an unwholesome\nenvironment. A normal appetite or impulse may be given a pathological\ntrend by bad influences. And one has to reckon, moreover, with degrees of\nhereditary aptitude to crime. Just what is the measure of normality? To\nwhat extent by developing to their highest point certain inhibitive or\nopposing tendencies, can we counteract certain inherent proclivities for\nwrong-doing? By what means shall we sift the congenital defectives from\nthe victims of suppressed opportunities? These and kindred questions\nconfront us at the very outset of our studies of crime and delinquency. It\nis obvious that although we may institute the strictest elimination of the\nsocially unfit, unless we can provide a wholesome environment for the fit,\nlapses into unfitness are sure to recur.\n\n=Feeble-Mindedness Often a Factor.--=The conviction is steadily growing\namong students of human heredity that a considerable amount of crime,\ngross immorality and degeneracy is due at bottom to feeble-mindedness and\nthat, therefore, if we can once eliminate feeble-mindedness, these vicious\naccompaniments will at the same time in equal measure disappear. Goddard,\nfor example, one of our authorities on the inheritance of\nfeeble-mindedness, is convinced that a large proportion of the delinquent\ngirls who fill our reformatories are actually feeble-minded. They are\noften the higher grade or moron type, and their mental condition remains\nunsuspected because they have never been thoroughly tested in this\nrespect.\n\n=Many Delinquent Girls Mentally Deficient.--=According to Havelock Ellis,\n2,500 of some 15,000 women who passed through Magdalen homes in England\nwere definitely feeble-minded and were known to have added a thousand\nillegitimate children to the population.\n\nThe preliminary reports of the so-called white slave investigations now in\nprogress in New York City classes 25 per cent. of these unfortunate women\nas mentally incapable of taking care of themselves. Other investigations\nindicate that from 40 to 60 per cent. of this class of women are\ndefectives. For example, from the report of the Massachusetts \"Commission\nfor the Investigation of the White Slave Traffic, So-Called,\" one reads:\n\"Of 300 prostitutes, 154, or 51 per cent., were feeble-minded. All\ndoubtful cases were recorded as normal. The mental defect of these 154\nwomen was so pronounced and evident as to warrant the legal commitment of\neach one as a feeble-minded person or as a defective delinquent.... The\n135 women designated as normal, as a class were of distinctly inferior\nintelligence. More time for study of these women, more complete histories\nof their life in the community, and opportunity for more elaborate\npsychological tests might verify the belief of the examiners that many of\nthem were also feeble-minded or insane.\"\n\nThe data from some of our public reformatories, industrial schools and\nstate homes for delinquent girls, are very instructive in this respect.\nReports from a number of such institutions show that many of their inmates\nare mentally subnormal. The proportions range from thirty-three per cent.\nin the New Jersey Reformatory at Rahway to eighty-nine per cent. in the\ninstitution at Geneva, Illinois.\n\n=Institutional Figures Misleading.--=However, significant as are these\nfigures from institutions for delinquents, one should not be misled by\nthem. They are undoubtedly not representative of offenders in general, but\nof a selected group of the most hopeless cases. In the first place the\nmore capable individuals escape the dragnet which lands the defective\ndelinquents in an institution, and furthermore, because of liberal systems\nof probation, only the more incorrigible or the very stupid make up the\nbulk of the population of such places. Miss Augusta F. Bronner, assistant\ndirector of the Psychopathic Institute of the Juvenile Court of Chicago,\nfrom a careful study of five hundred and five cases of delinquent boys and\ngirls in the Detention Home, chosen with as little selection as possible,\nfinds the proportion of mentally subnormal among them to be less than ten\nper cent.\n\n=Many Prisoners Mentally Subnormal.--=Doctor Walter S. Fernald, of the\nMassachusetts School for Feeble-minded, estimates that \"at least 25 per\ncent. of the inmates of our penal institutions are mentally defective.\"\nAmong the various available estimates at hand this seems to be a fairly\nconservative approximation. Hastings H. Hart points out that this\ncalculation of 25 per cent. means that there are 20,000 adult defective\ndelinquents in prison, and 6,000 youths in juvenile reformatories, or a\ntotal of 26,000 in custody in the United States.\n\n=The Inhibitions Necessary to Social Welfare Not Well Established in\nAll.--=But let us look at this matter of delinquency a little more in\ndetail. In common with other living creatures mankind has two strongly\npredominating instincts without which there can be no prolonged individual\nor racial existence, namely, the self-preservative and the reproductive.\nSays Schiller: \"While philosophers are disputing about the government of\nthe world, Hunger and Love are performing the task.\" Under\nself-preservative would be included everything pertaining to food,\nproperty and self-protection. In addition, however, man, together with\ncertain other social animals, has developed a third set of activities or\ninstincts--an impulsion toward the preservation of the community to which\nhe belongs--and so far has this evolved in his case that it outranks in\nimportance the other two. For the highest accomplishments and ideals of\nthe race are in last analysis expressions of this social instinct. But\nwith this system of mutual help comes the necessity of certain restraints,\nbecause for society to exist its members must impose upon themselves, or\nhave imposed upon them, certain inhibitions of their self-preservative and\nreproductive instincts.\n\nBeing a late acquisition of the race and less firmly ingrained, the social\ninstinct is not well established in all individuals. Some have it\nsufficiently strong to exercise of their own accord the necessary\ninhibitions of other instincts. Experience has shown that others, either\nthrough a lack or through a wrong cultivation of it, can not or will not\ndo so unaided. For the latter, society has instituted certain conventions\nand the criminal law whereby through a system of restraints and\npunishments such an individual is held in check either by actual physical\nrestraint of his property or person or through the powerfully inhibitive\nfactors of shame or fear. Man as a normal member of society must\nconstantly take heed of the physical, intellectual or moral danger the\nexercise of a given feeling, action or procedure on his part will bring to\nhumanity, and govern himself accordingly.\n\nBut it is in just these very inhibitions that mental defectives are\nlacking. They are almost invariably anti-social types because they are\nunable to establish the personal abstentions which are necessary for the\ngood of the community. While in the individual of innate normal mentality\nanti-social traits may have developed because of improper training or\nsurroundings, in mentally defective types some factor or factors necessary\nto normality have been left out of their make-up and as a result they are\noften wholly lacking in social instincts or have these so feebly developed\nthat education and exhortations toward social ideals are fruitless. We can\nnot appeal successfully if there is nothing to appeal to; we can not\ndevelop something out of nothing.\n\n=The High-Grade Moron a Difficult Problem.--=One great difficulty in\nidentifying the high-grade morons who are a bountiful source of our\ncriminals is our almost universal failure to recognize that a memory test\nalone is not sufficient to determine the mental responsibility of an\nindividual. Not only memory, but judgment, will-power and perhaps, also,\nto a lesser degree, the powers of attention and concentration are all\nindispensable elements in the make-up of a normal individual. There are\ncases on record of imbeciles with prodigious memories, yet hopelessly\nincapable of caring for themselves or of respecting the rights of others.\nIn fact certain types of morons, usually cunning, often prepossessing and\nsuperficially clever, are characterized by good memories and will\n_moralize_ volubly, although their wills are too weak to inhibit impulses\nwhen they face temptation. It is obvious that just in proportion as the\nintelligence of the high-grade degenerate approaches normality and yet\nremains abnormal, the more dangerous he may become to society.\n\n=Degenerate Strains.--=A number of family records are now available which\nshow convincing evidence of the hereditary nature of a degeneracy which\nfinds expression in pauperism, immorality and crime.\n\nAs has already been pointed out, there is reason to believe that much of\nthis is based in some degree on feeble-mindedness. One of the most\nremarkable of these is the recent study on degeneracy by Goddard as set\nforth in his book called _The Kallikak Family_. The record is that of six\ngenerations of descendants from an original progenitor to whom the\nfictitious name of Kallikak has been assigned. This individual, descended\nfrom good stock, before his marriage met a feeble-minded girl by whom he\nbecame the father of a feeble-minded son. Later he married a normal woman\nby whom he had normal children. Thus from one normal father have sprung\ntwo lines of progeny, one vitiated with feeble-mindedness, the other\nnormal. The comparison may be readily made by drawing up in parallel\ncolumns the data as follows:\n\n            LINE A                                 LINE B\n\n  In five generations 480 direct     In five generations 496 descendants\n  descendants from a normal father   from the same normal father as in\n  father and a feeble-minded         Line A and a normal mother have the\n  mother have been accounted for     following record:\n  as follows:\n\n  143 known to be feeble-minded.     All but one of normal mentality.\n\n  291 mental status unknown or       Two men known to be alcoholic.\n  doubtful.\n\n  36 illegitimate.                   One case of religious mania.\n\n  33 sexually immoral, mostly        Among the rest have been found\n  prostitutes.                       nothing but good representative\n                                     citizenship, numbering doctors,\n  24 confirmed alcoholics.           lawyers, educators, judges,\n                                     traders, etc.\n\n  3 epileptics.                      No epileptics or criminals.\n\n  82 died in infancy.                Only fifteen children died in\n                                     infancy.\n\n  3 criminals.\n\n  8 keepers of disreputable houses.\n\n  46 only ones known to ben ormal.\n\nCertainly there is abundant food for thought in these two records.\n\nIf we take still other families of criminal or degenerate antecedents the\nsame multiplication of viciousness, as a rule, is in evidence. Thus,\n_Margaret, the Mother of Criminals_, has left a progeny of some 700\npaupers, prostitutes and criminals, some of the women bearing as many as\ntwenty children. The famous Jukes family, so often cited, with its 310\nprofessional paupers, 300 deaths in infancy, 440 physical wrecks from\ndebauchery, 50 prostitutes, 60 habitual thieves, 7 murderers, and 130\nother convicts out of a total 1,200 descendants who have been identified,\nhas alone cost the state of New York $1,250,000 in the care of its\ncriminal, defective and immoral progeny.\n\nAnother family record, the Zeros, reported by Poellman, of Bonn, starts\nwith a female confirmed drunkard. In six generations of her descendants,\ntotaling 800 people, Poellman found 102 professional beggars, 107\nillegitimates, 181 prostitutes, 54 in almshouse, 76 convicted of serious\ncrime, 7 of murder, and costing some $1,206,000. Or we might cite the\nso-called _Tribe of Ishmael_, the progeny of a neurotic man and a\nhalf-breed woman. They have spread their ill-favored spawn over various of\nthe central states in a veritable flood of imbecility and petty crime. And\nto these families may be added the records of _The Hill Folk_, _The\nPineys_, or others of the several recent studies of degenerate strains.\nAll bear the same message of rapidly multiplying degeneracy.\n\n=Intensification of Defects by Inbreeding.--=Most of these regional\nsurveys that are now in progress show that there is particular danger in a\npopulation becoming broken up into small communities and isolated. Under\nsuch conditions there is a pronounced tendency to intermarry, and if\ndeterioration is already present in the stock such communities become\ncenters of marked degeneracy. The situation is well exemplified in the\nfollowing excerpt from Davenport:\n\n    \"I have been going over the records of one family in New York, the\n    so-called Nam family. There were 55 per cent. consanguineous matings,\n    marriage between cousins, in one generation, and, owing to the fact\n    that the strain was already loaded with defects, we can see how these\n    defects were concentrated by these cousin marriages, so that about 90\n    per cent. of the strain is feeble-minded. There were fully 90 per\n    cent. of the men who are unable to resist the lure of liquor.\n    One-fourth of the children are born illegitimates. Infanticides,\n    incest, murder, harlotry, are all over the chart. This is a highly\n    inbred community, keeping a nearly pure strain of social defects, and\n    the cost to the community has been a million and a half on a fair way\n    of figuring, not directly in the care, but indirectly in the damage\n    they have done. These constitute a rural community. Out of this\n    community we can trace those who have gone to the cities and become\n    murderers, prostitutes and thieves. They are not confined to one\n    state; they spread out over the country. One branch of the family came\n    to the state of Minnesota. We sent to one of Doctor Rogers' trained\n    field workers to learn whether she had ever heard of this family, and\n    received a reply that the family was well known to social workers in\n    the state of Minnesota. These strains of degenerates are not local\n    matters at all; they are matters of national interest.\"\n\nConcerning crime and delinquency, we find that all evidence tends to show\nthat an alarming increase is in progress although satisfactory data are\nhard to obtain. It is certain that there is a tremendously\ndisproportionate increase in the number of prisoners in recent years\ncompared with general population, for while the total population has\nincreased three and one-half fold, the prison element has increased\nfifteen fold. According to Wier, in this country there are four and\none-half times as many murders for every million of our population to-day\nas there were twenty years ago.\n\nIt may be urged that this increase in prison population is not a\ndisproportionate increase in the number of defectives or criminals, but\nonly an increase in the number sent to prison, and this is probably a\npartial truth--but when we recall such pedigree as those of the Nams, the\ndefective line of Kallikaks and other known unsound strains, he must be\nhopeful indeed who can find much consolation in this supposition. In any\nevent, no such uncertainty exists regarding the number of murders and\nhomicides, since these have in all probability been as fully recorded in\nthe past as at present.\n\n=Vicious Surroundings Not a Sufficient Explanation in Degenerate\nStocks.--=It is sometimes urged that we are not dealing in such cases with\ndegenerate strains, but merely with unfortunate individuals who have been\nsubjected to pernicious surroundings from the beginning. And it can not be\ndenied that parents who are mentally defective, dissipated or syphilitic\nafford most noxious developmental and environmental conditions for their\nchildren. But when one notes how intimately the moral degeneracy in such\nstocks is bound up with some degree of feeble-mindedness, he is strongly\nskeptical toward the sufficiency of such an interpretation, although\nenvironment undoubtedly intensifies the results. Concerning this point\nDavenport says:\n\n    \"We have certain methods of testing whether it is bad environment or\n    bad breeding which produced these people. Some of the children have\n    been taken at an early age and 'placed out'. We have traced their\n    subsequent history. In most cases they have turned out quite as bad as\n    those who have remained at home. In a few cases they have turned out\n    well, but it is also true that some of the children who remained at\n    home in bad environment have turned out well.\"\n\nAnd to Davenport's testimony may we add that of Doctor Wilmarth, who,\nspeaking of children at the home for feeble-minded, says:\n\n    \"In no place is this subject of the power of heredity in relation to\n    environment so easily studied as among our children. A group of many\n    little children came to us from the state school, being untrainable\n    there. They have had with us the same teaching and the same\n    companionship. Each one has lived, eaten and slept among the others,\n    and, so far as we know, with but one exception, those of vicious\n    parentage have turned instinctively to vicious traits by preference,\n    while those of simple but honest stock do evil things only under\n    strong temptation, and do not persist in them after the wrong is\n    pointed out.\"\n\n=By No Means All Delinquents Are Defectives.--=One must not overlook the\nfact, however, that _delinquent_ and _defective_ are by no means\nsynonymous terms, and that many delinquents are with little doubt the\nproduct of adverse social circumstances.\n\nThe recent careful work of Doctor William Healy[13] in connection with the\njuvenile delinquents of Chicago shows convincingly that the underlying\ncausations of delinquency are many. Such factors as immorality or constant\nquarreling of parents, bad companions, lack of parental control, defective\nsense organs, debilitating habits, lack of healthy mental interests and a\nhost of other environmental factors are not infrequently sufficient in\nthemselves to develop delinquency in the absence of inherited deficiency.\nThe present-day efforts of the student of heredity should not be\nmisunderstood. They are not attempts to make all delinquents out\ndefectives, but rather to determine what percentage of delinquents may be\nlegitimately reckoned as defective and to make the facts known. Since\nthere is no longer any reasonable doubt that, to express it in the mildest\nterms, an amount of delinquency far from negligible is due in great\nmeasure to congenital omissions or propensities, then the sooner the\npublic learns this the better, for we may then set about supplementing our\npresent efforts at race betterment through external improvement by\ndevising means of cleansing the fountain source as well.\n\nIt can scarcely be doubted that the average man differs little if any in\ninherent personality and capacity from many a criminal who is such by\noccasion rather than by undue predisposition. Who can truthfully answer\nhow many individuals there are who are not potentially criminals to some\nextent, given sufficient evocative conditions of ignorance, vice, adverse\neconomic pressure and undue temptation?\n\n  \"Virtue itself turns vice, being misapplied.\"\n\n=No Special Inheritable Crime-Factor.--=The main difficulty in trying to\nfind a hereditary basis for crime lies in the multiplicity of things crime\nmay be. The individual impulsions which lead to certain offenses may be\nutterly different from those which conduce to others. Undoubtedly many\ninborn tendencies which are perfectly normal or neutral in themselves may\nbe warped by circumstances into the commission of what are classified as\ncrimes. The moral man may have the same desire for a thing that the\ncriminal does, but when he finds that this desire can only be gratified by\ninjury to others, he inhibits it because of his repugnance to such injury.\nThe criminal makes no such inhibition.\n\nIn general, crime means an offense of some kind against person, property\nor state. But a biological analysis of it, could it be made, would require\namong other things knowledge of crime in terms of motive or lack of\nmotive, whether the act was intended to benefit the perpetrator, some\nother person, or even the race or state; whether the offense was one of\ndishonesty, of cupidity, of lust, or of violence against another.\n\nAs a matter of fact no satisfactory classification of crime can be made\nsince so many factors enter and in such varying degrees. Most\nclassifications made in our legal codes are a hodge-podge based on a\nmixture of motive on the part of the participant, degree of turpitude\ninvolved, nature and extent of the injury inflicted, and the object\nagainst which the offense was perpetrated, whether an individual, society\nor the state. Moreover, it must not be forgotten that in many instances\nwhat was crime in the past is no longer so, and vice versa many things\nwhich are regarded as criminal to-day were not considered so in the past.\nSo the futility of seeking a specific inherent propensity for \"crime\" is\nmanifest. How, for instance, in terms of hereditary determiners shall we\ndraw the fine lines of distinction among those who bribe legislators and\nlegal officials, those who are avaricious and dishonest in the world of\ntrade, and those who are wilfully obtuse in providing proper safeguards\nfor employees?\n\n=What Is Meant by a Born Criminal?--=All we can do is to fall back on the\nassurance that any act directly or indirectly injurious to society is an\noffense, and that those offenders who are congenitally unable to\ndistinguish between what is generally accepted as right and wrong, or who\nif recognizing this are nevertheless uncontrollably impelled toward or are\nunable to refrain from anti-social acts because of some inherent condition\nof intellectual or volitional make-up, may be legitimately classed as\nindividuals born with an aptitude for crime and social transgressions. In\nsuch individuals the natural mental make-up is lacking in some of its\nnecessary elements so that memory, judgment, or will-power are not up to\nthe minimum that is necessary for the establishment of proper conduct. In\nsome cases, apparently, this lack finds expression in almost any kind of\nvice or crime into which circumstances happen to lead the individual. In\nothers, however, there seem to be tendencies toward the commission of\ncertain types of crime or vice. Certain family strains are characterized\nby petty thieving, others by deeds of violence, and still others by sexual\noffenses. Certain types of mental defect are closely associated with\ncertain crimes. Thus sufferers from incipient paresis seem particularly\nprone to commit assaults and larceny; epileptics, crimes of brutality and\nviolence.\n\n=The Epileptic Criminal Especially Dangerous.--=One of the characteristics\nof epilepsy, indeed, emphasized by various psychiatrists, is that\nfrequently it leads to loss of those forms of self-restraint which are\nabsolutely indispensable to morality and the safety of society. Cruelty,\natrocious sexual offenses and other vicious crimes are the result. It is a\nnoteworthy fact, moreover, that often in the milder forms of affliction,\nwhere instead of well-marked convulsions only momentary lapses of\nconsciousness occur, the greatest amount of mental and moral deterioration\nand fluctuation is sometimes found.\n\nThe situation as regards the epileptic is well presented by Doctor William\nHealy, Director of the Juvenile Psycopathic Institute of Chicago, in an\narticle entitled \"Epilepsy and Crime; the Cost\", in the _Illinois Medical\nJournal_, November, 1912. He says:\n\n    \"In the work of our institute,[14] which represents the most\n    thoroughgoing research into the genetics of criminalism ever\n    undertaken in this country, we have with the help of parents and\n    others carefully studied nearly 1,000 young repeated offenders. We\n    have found that no less than 7-1/2 per cent. of these are ordinary\n    epileptics, and we have reason to suspect others. This by no means\n    represents the total number of epileptics seen in connection with\n    juvenile court work, where, of course, first offenders as well as\n    large numbers of dependents are seen. In addition to my above\n    enumeration, other cases seen by the Detention Home physicians and\n    myself amount up to many scores of cases. If one remembers that it is\n    ordinarily calculated that one person in every 500 is epileptic, the\n    significance of this high criminal percentage is clear, and the\n    practical bearing of it is still further accentuated by the fact that\n    some of the worst repeaters are epileptics, and that many of the\n    gravest crimes are committed by those unfortunates. The connection\n    between epilepsy and crime has everywhere been recognized by students\n    of the subject, but it apparently needs constant emphasis in order\n    that common sense steps may be taken toward guardianship of these who\n    suffer from a disease which wreaks such extravagant vengeance on\n    society.\"\n\n=Mental Disorders Most Frequently Associated With Crime.--=Doctor Charles\nMercier, an English authority on crime and insanity, in enumerating the\nmental disorders most frequently associated with crime, places the\ninsanity of drunkenness first. Any one who will take the trouble to verify\nthe facts in his own community will find that a large percentage,\nfrequently considerably over half, of the arrests made by the police are\nfor acts committed while the offender was more or less under the influence\nof alcohol. Next to drunkenness among mental disorders which lead to crime\nDoctor Mercier places feeble-mindedness. Next to feeble-mindedness comes\nepilepsy; then paranoia or systematized delusion; next paresis; and lastly\nmelancholia.\n\nParanoics are peculiar in that they are particularly apt to attack persons\nof prominence. Highly egotistical, they almost invariably believe\nthemselves or some one or some cause dear to them, the subject of a plot,\nperhaps to rob them, to torture them, to steal their inventions or\nliterary productions, or to persecute them in some way. Two if not three\nof our murdered presidents owe their assassinations to paranoics. Many\nrulers have been attacked and some killed by such insane individuals. Most\nof the \"cranks\" who write threatening letters are lunatics of this type.\n\nOf the kinds of mental unsoundness known to be inheritable which are of\nspecial significance from the standpoint of crime and delinquency\nundoubtedly feeble-mindedness ranks first. We have already seen that as\nour methods for detecting the higher grades of feeble-mindedness become\nmore accurate we disclose in border-line cases a veritable hot-bed of\nmental incapacity suitable for the engendering of the criminal and the\nvicious. Here in addition to some of the more pronounced criminal types\nbelong hosts of our chronic petty offenders, our sexually vicious and our\n\"won't-works\". One interesting outcome of a recent investigation into the\narmy of unemployed in England was the discovery of the general unfitness\nof these unemployed. In our own country the habitually unemployed are so\nnot because of lack of work, but largely because it is unprofitable to\nemploy them.\n\n=The Bearing of Immigration on Crime and Delinquency.--=Perhaps in no\nfield more than this of crime and delinquency, especially in so far as it\nis based on innate deficiency, does the gravity of the immigration\nquestion impress itself on us. How stupendous this problem[15] has become\nmay be realized from the fact that according to the census of 1910,\n13,345,545, or one out of seven of the inhabitants of the United States,\nwere foreign born. And if we add to these the 18,897,837 of whom one or\nboth parents were of foreign birth, we reach the astonishing total of over\n32,000,000, or more than one-third of our total population, who are\nforeign born, or who have one or both parents of foreign birth.\n\nDuring the decade from 1900 to 1910, 8,500,000 foreigners came to the\nUnited States, of whom 5,250,000 remained to make a permanent home. This\nshows how rapidly our whole population might be radically changed. In\nrecent years the source of our immigrants has shifted proportionately from\nnorthwestern Europe to southern and eastern Europe (Italy, Austria-Hungary\nand Russia), and whether for weal or woe this new blood must inevitably\nleave its impress upon us. Does it not behoove us then to seek with\nanxious eyes some knowledge of these invading hordes with whom we are to\nmingle our life-blood?\n\nEven the most superficial examination may well cause us grave concern. We\nfind that in one year (1908) at Ellis Island alone, 3,741 paupers, 2,900\npersons with contagious disease, 184 insane, 121 feeble-minded, 136\ncriminals, 124 prostitutes and 65 idiots were denied entrance, and yet,\naccording to the estimate of Doctor F. K. Sprague, of the United States\nPublic Health Service, probably only about 5 per cent of the mentally\ndeficient and 25 per cent. of those who will become insane have been\ndetected. When confronted by such data we can begin to realize what we are\nfacing. Others estimate that from 6 to 7 per cent. of the immigrants who\nare now arriving are feeble-minded. We learn further that recently while\nthe foreign-born population of New York state was about 30 per cent., the\nforeign-born population of the insane hospitals of the state was over 43\nper cent., and at one time approximately 65 per cent. for New York City.\nIn one year (1908) 84 per cent. of the patients in Bellevue Hospital, New\nYork City, were of foreign parentage. Paresis, which probably always has\nsyphilis as its antecedent, is proportionately twice as prevalent among\nforeigners as among natives in New York City.\n\nBut from the standpoint of inheritance, however great the danger may be\nfrom classifiable defectives, it is probably far greater from that much\nlarger class of aliens we are now receiving with open arms who are below\nthe mental and physical average of their own countries. Moreover, with our\npresent system of inspection there is no way of detecting the grades of\nfeeble-mindedness above idiocy and imbecility in the great numbers of\nforeign children under five when brought in, who are beginning to show up\nin alarming numbers in the schools of some of our larger cities. About\nthirty per cent. of the annual increment of our population is due to\nimmigration and not to births; and once in our country the alien far\noutbreeds the native stock, with relatively little increase in death-rate,\nthus making a double contribution to the increase of population. When we\ntake all these facts into consideration it certainly is high time that we\narouse from our self-complacent attitude and consider the whole question\nof immigration most earnestly.\n\nIn spite of the fact that many individuals are caught in the net of\ninspection at our portals, it is clear that still more rigid rejection[16]\nis imperative. The inspectors at our various ports are doing the best\nthey can under the circumstances, but there are at present too few of them\nand they are too restricted in their powers to meet the situation\nsatisfactorily. Moreover, when at one of our ports in one year (1910), of\n1,483 immigrants certified by the inspecting surgeons as unfit to land\nbecause of serious mental or physical defects, 1,370 were landed anyway,\nit is evident that there is a strong and reprehensible pull somewhere to\nevade the obvious intent of the law.\n\nIt remains for us as a people to decide whether we shall continue to let\nthe large employers of cheap labor, the railroad and steamship agents and\nbrokers, who care nothing about the innate fitness of the immigrants they\nbring, determine the character of our future population, or whether we\nshall insist on a proper regulation of this flood so that we may receive\nonly an honest, intelligent, industrious and healthy stock. To continue to\nabsorb these aliens with as little selection as we now do is nothing short\nof criminal carelessness. Let us not be deceived by the promptings of a\nmisguided sentiment, \"The voice is Jacob's voice, but the hands are the\nhands of Esau.\" The voice is Jacob's voice, nor should this voice of the\neasily persuaded, the sentimentalist, the interested organization to which\nthe relatives of the defective alien belong, or any other pressure move us\nfrom our obvious duty of refusing to fasten upon this country an incubus\nof degeneracy for which we as a nation are in no way responsible.\n\nTo render us safe we should not only have more carefully drawn laws and\nmore rigid selection at our ports of entry, but we should if possible\nalso know the stock from which our future citizens come. This is\npeculiarly desirable for such defects as feeble-mindedness and various\nother mental imperfections, some of which require prolonged observation\nfor detection. Davenport estimates that it is wholly within the realm of\npossibility and good business sense to maintain a corps of trained\ninspectors abroad in the chief centers from which our immigrants come who\nshall certify the desirable applicants. He makes the point that the\nnational expense would be far less than the cost of maintaining the army\nof defectives we are now admitting to our own country, many of whom almost\nimmediately become public charges, to say nothing of the hordes of\ncarriers who though normal themselves, will transmit undesirable traits.\n\n=Sexual Vice.--=As to sexual vice, the skein is indeed a tangled one.\nSince nine-tenths of the difficulty centers in a lack of self-restraint,\nand inasmuch as the mating instinct is one of the strongest that tugs at\nthe flesh of humanity, it is obvious that those by nature deficient in\nvolitional control will almost without exception give way to the call. So\nas might be expected the hordes of our feeble-minded and epileptic are\nalways a source of grave danger in this respect. However, the mentally\nenfeebled are by no means the only offenders; indeed, they are probably\nnot the majority. The true situation is finally dawning on society and the\nreformer's call for instruction in \"sex-hygiene\" resounds through the\nland. The whole matter is one of the most perplexing and momentous that\nconfronts us to-day.\n\n=The Question of School Instruction in Sex-Hygiene.--=While the writer\ndoes not for an instant underestimate the gravity of the situation, and\nhas only contempt for the nonsense that is palmed off on children about\ntheir origin, or the indelicate self-consciousness which puts under the\nban the discussion of so serious a problem by adults, still he is not\nconvinced that the universal teaching of the subject to children in\nschools by the average teacher, as advocated by some, is to be the\nsolution of the matter or is even a wise attempt at solution. Yet he\nfreely admits that he is possibly overfearful of the effects of the\nundesirable features of such instruction. True it is that all children do\nlearn, frequently at an astonishingly early age, about sex, and their\nknowledge is usually of an undesirable kind from unreliable and often\nvicious sources, and it is equally true that parents, either through\nignorance or prudery, generally can not be depended on to give the child\nnecessary instruction. But before entering on a wide-spread campaign of\nundiluted sex-instruction in schools might it not be more prudent to make\nan attempt toward reaching fathers and mothers and convincing them of the\nnecessity of dealing more frankly and intelligently with their children\nregarding sex?\n\nEven to the novice in psychology the powerful nature of suggestion is\nknown, and with this knowledge before us, is it not wiser to strive in the\nmain to keep the child's mind off of sex rather than specifically to focus\nit on it by special convocations and discourse? If our psychology means\nanything, then the worst possible thing we can do for a child is to make\nhim unduly sex-conscious. Something might be done profitably perhaps in\nschools in an unobtrusive way by specially gifted persons, but the\nself-conscious way in which most teachers go about topics of sex is\ncertainly not reassuring to the thoughtful observer as regards the benefit\nderived from such instruction. The one evident method of accomplishing\nwholesome sex-instruction in schools, devoid of all possibility of\nundesirable suggestion and sex-consciousness, is in the form of biological\nwork where plants and animals are studied in all their relations, the\nsubject of propagation being taken up in as matter-of-fact a way as the\nfunctioning of any other organ system of plants or animals. In such a\ncourse, long before the subject of sex in higher animals need be\napproached the pupil will have developed an attitude of mind which will\nlead him to see nothing unusual or suggestive in the function of sex no\nmatter where it may be found. Incidentally, inasmuch as the manner in\nwhich germs affect living organisms should be studied in such a course\nanyway, it would be a simple matter to give all necessary information\nabout the dangers of infection from venereal diseases.\n\n=Mere Knowledge Not the Crux of the Sex Problem.--=However, desirable as\ncorrect knowledge about sex is, knowledge alone is not the crux of the sex\nproblem. The moral dangers and abuses that we are trying to circumvent lie\nrather in the realm of the emotions than that of the intellect. The\nproblem must be solved from a broader foundation than mere information.\nThe all-important consideration is the early establishment of general\nhabits of self-control so that these may become incorporated in the\nnervous organization of the child and become inhibitory anchors against\npassions and temptation. Children must be taught to suppress the present\nimpulse, to sacrifice the immediate pleasure for the more distant or\npermanent good. They must be practised in calling up feelings that will\ncounteract other promptings which if followed blindly are inimical to\nsocial welfare. Their control must come from within not as a matter of\nexternal compulsion. That way character lies.\n\nSo in viewing the problem of sexual hygiene the writer feels that our\nattempts toward damming the torrents in the adolescent by a belated effort\nat verbal instruction on sex-hygiene is at best only a palliative or an\nattempt to cure the symptoms of a more deeply-seated, organic, social\nmalady. The treatment should have been in progress long before in the form\nof training in self-control, and in the inculcation of the sense of\ndignity and self-respect which springs from the individual's consciousness\nof being, not a slave to his desires, but his own master. This, together\nwith the judicious schooling of boys in a greater chivalry and respect for\nwomanhood, and of girls in the necessity of meriting such esteem, will, in\nmy estimation, carry us further than formal courses in sex-hygiene.\n\n=Early Training in Self-Restraint an Important Preventive of Crime and\nDelinquency.--=As to crime and delinquency in general, it is evident that\nthe same early training in self-restraint is a most important factor of\nprevention. A wise warden in charge of a large prison says, \"Most of these\nmen are here because they have not learned sufficiently the lesson of\nself-control.\" This is the age of preventive medicine, why not also of\npreventive crime and delinquency? Instead of confining our practise to\npunishing offenders, necessary as this may be under the present\nconditions, why not strive more to prevent the commission of offenses? As\nfar as normal individuals are concerned much can be done by early\ncultivation in self-discipline and through the establishment of moral\nbackbone by training in the overcoming of difficulties. Much, very much,\nalso remains to be done in the correction of wrong social conditions.\n\n=Unpardonable to Permit Delinquent Defectives to Multiply Their Kind.--=As\nfor our mental defectives and moral imbeciles, knowing now how strongly\nhereditary the underlying factors of these conditions are, and with no\npreventive or curative agents in sight, to let them produce progeny, is\nclearly unpardonable.\n\n\n\n\nCHAPTER X\n\nRACE BETTERMENT THROUGH HEREDITY\n\n\nMost of us have heard in one form or another the fairy story of the youth\non adventure bent, who was captured by the giant and under dire penalty in\ncase of failure was set the task of sweeping out the giant's stable before\nsundown. The peculiarity of this stable, it will be recalled, was that, as\nfast as the refuse was swept out at the door an even greater quantity\npoured in through the windows so that the sweeper, just in proportion to\nhis zeal, became more and more encumbered with his burden.\n\n=A Questionable Form of Charity.--=Though we smile at the childishness of\nthis legend, are we not as a civilized people attempting through our\ncharities a feat parallel to that of this unfortunate youth? We foster and\nfavor our social wastage with the inevitable result that it runs riot\nunder our sheltering hand and deluges us with an ever accumulating flood\nof its like. For are we not constantly building more asylums, sanitaria\nand prisons, to preserve more unfit, to produce more defectives, to\nrequire still greater numbers of asylums, sanitaria and prisons, to\npreserve more unfit, and so on in unending progression?\n\nAt nearly every period of history there have been certain individuals who\nhave seen the necessity of a state eliminating its supply of defectives.\n\n=Past Protests.--=For instance, we find the importance of this strongly\nurged by Plato. After pointing out the fact that the shepherd, in order to\nmaintain the standard of his flocks, bred only from the best individuals,\nas did likewise the huntsman with his dogs and horses, and the fancier\nwith his various pets, Plato went on to show the danger to the state of\nallowing the constantly increasing body of defectives and degenerates to\nmultiply their kind. Repeated expression of the same idea has occurred\nfrom time to time during the succeeding centuries.\n\nLittle heed was paid to these remonstrances, however, with the result that\nis known to us all. To-day, \"the glory that was Greece and the grandeur\nthat was Rome\" is still sung by the poet, but the original nations\nthemselves have long since passed into the night.\n\n=An Increasing Flood of Defectives.--=Strive to ignore the unpleasant\nfacts as we may, we have to admit that the same problem of what the human\nharvest shall be is with us in grave form to-day. The alarming phase of\nthe situation, however, lies in the fact that we are facing an ever\nincreasing flood of social wastage.\n\nBut _why_ this increase of defectives? It can not be attributed to\noppression, to grinding poverty, or to decline in attention to our sick\nand needy, for never was prosperity greater, never were charities more\nflourishing, never such activity in the search for palliatives and cures.\nThe simple fact is that we are breeding our defectives. The human harvest\nlike the grain harvest is based fundamentally on heritage. And to get a\nbetter crop of human beings, we must, as with other crops, weed out bad\nstrains.\n\nTo whatever source of information we turn the facts are essentially the\nsame. Abroad we find that in England, for example, the ratio of defectives\nto normals more than doubled between 1764 and 1896. At home, from the\ninvestigation of Davenport and Weeks we learn that in the state of New\nJersey the number of epileptics doubles every thirty years. And other\ninvestigators estimate that the fecundity of mental defectives in general\nis about twice as great as that of the average of our population. In a\nrecent report of the New York State Board of Charities we read, \"There are\nabout thirty thousand feeble-minded persons in the state of New York, of\nwhom four thousand are intermittently sequestered while twenty-six\nthousand who are a menace to society are at liberty and may produce the\nunfit.\" And a passage from the last Massachusetts report reads as follows:\n\"We have been obliged to refuse a very large number of applicants for the\nadmission of feeble-minded women--many of whom have given birth to one or\nmore children. The prolific progeny of these women almost without\nexception are public charges from the date of their birth.\"\n\nHow fertile defective types may be is shown by a passage in one of Doctor\nWilmarth's papers which runs as follows: \"One feeble-minded woman, now\nremoved from this state, had by different men eighteen children in\nnineteen years, she alleges.\" In a letter Doctor Wilmarth tells me that\nthe birth of the twenty-third child of this woman has just been\nannounced! In one English workhouse Potts reports sixteen feeble-minded\nwomen who have produced one hundred sixteen mentally defective children,\nand Branthwaite ninety-two female habitual drunkards who have had eight\nhundred fifty babies. If we include the two million individuals cared for\nannually in various institutional homes, hospitals and dispensaries as\ndependents, the estimated total of insane, feeble-minded, epileptic, deaf\nand dumb, criminals, juvenile delinquents, paupers and other dependents in\nthe United States in 1910 was approximately three million, or one in every\nthirty of our population! With the higher fertility of certain of these\nclasses and with only a small percentage under custodial care where will\nit all end? Is it not time for us to waken from our lethargy and stem this\ntide of national deterioration?\n\n=Natural Elimination of Defectives Done Away With.--=With our improved\nmethods of sanitation and care of the sick, the pauper and the defective,\nthese classes have been freed from the stress of an environment that under\nnatural conditions would have resulted in their premature death and\nconsequent infertility. Or in the terminology of the biologist, we have\ndone away with the factor of _natural selection_, the factor which in\nstate of nature keeps all races purged of the unfit, the ill-adapted. With\nthis restraining, and purifying influence removed, however, the weakling,\nthe defective, may arrive at maturity and commingle his blood with that of\nthe strong, with the inevitable result that the general vigor of the\nprogeny from generation to generation is sapped and progressively\nundermined. Thus we are confronted by the stubborn fact that through\npresent humanitarian methods we are driving the race toward decadence.\n\n=Why Not Prevent Our Social Maladies?--=Now there is no reasonable person,\nI think, who will not admit that the motives underlying our modern\naltruistic practises are the noblest fruitage of our slow upward struggle\nfrom the brute to man. As humane beings, we can not cast aside these\nprinciples and return to the painful and pitiless method of nature which\nwould leave the sick and the defective alone to perish miserably; the\nsacrifice would be too great.\n\nIs there then no escape from this dilemma? To this query the modern\nstudent of heredity answers yes; let us but add more wisdom to our charity\nand the enigma is solved. We need no sacrifice of pity but rather an\nexpansion of it. Let us but extend our vision from immediate suffering to\nthe prospective suffering of the countless unborn descendants of our\npresent unfit and ask ourselves the question, why should they be born? Why\nnot prevent our social maladies instead of waiting to cure them? This is\nthe province of eugenics.\n\n=Eugenics Defined.--=The term Eugenics was coined in 1883 by Francis\nGalton in his book entitled _Inquiries Into Human Faculties_, and we may\ntherefore look to him for a satisfactory definition. He says, \"Eugenics is\nthe study of the agencies under social control, that may improve or impair\nthe racial qualities of future generations, either physically or\nmentally.\" And again, \"I take Eugenics very seriously, feeling that its\nprinciples ought to become one of the dominant motives in a civilized\nnation, much as if they were one of its religious tenets.... Man is gifted\nwith pity and other kindly feelings, but he also has the power of\npreventing many kinds of suffering. I conceive it to fall well within his\nprovince to replace natural selection by other processes that are more\nmerciful and not less effective. This is precisely the aim of Eugenics.\nIts first object is to check the birth-rate of the unfit instead of\nallowing them to come into being, though doomed in large numbers to perish\nprematurely. The second object is the improvement of the race by\nfurthering the productivity of the fit, by early marriages and the\nhealthful rearing of their children.\"\n\n=Improved Environment Alone Will Not Cure Racial Degeneracy.--=While many\nan enthusiastic humanitarian is laboring under the assumption that if we\ncan improve external conditions human deficiencies will disappear, the\nstudent of heredity realizes that this is in large part a delusion unless\nwe can secure an accompanying improvement in intrinsic qualities of the\nhuman species itself through the suitable mating of individuals. Just as\nthe intelligent farmer to-day demands selected seed as well as good soil\nand proper cultivation, so one with the facts of heredity at hand would,\nas he views social problems, urge the fundamental importance of having\nselected stock with which to start. No shifts or shapings of environment\nwill ever enable men to \"gather grapes of thorns or figs of thistles.\"\n\n=Heredity and Environment.--=To wrangle over the question of which is the\nmore important, heredity or environment, is about as idle a proceeding as\nto argue which is the more important, the stomach or something to put in\nthe stomach. Man would soon come to grief without either. So, too, the\nquestion of human development is not one of heredity alone nor of\nenvironment alone; both are necessary and must work hand in hand. Dormant\ncapacities must have proper environment to call them forth, but on the\nother hand no kind of environment can evoke responses if some degree of\naptitude is not present.\n\nProfessor Thorndike undertook experiments with groups of school children\nof high and of low initial ability respectively to determine whether equal\nopportunity or equal special training would produce an equalizing effect\nin easily alterable traits such as rapidity in addition and the like.\nWithout exception he found that at the end of such experiments, although\nboth groups had improved, the superior individuals were farther ahead than\never, that equality of opportunity and training had widened rather than\nnarrowed the gap between the two classes. Others who have made special\nstudies on the causes of individual differences have come to the same\nconclusion; namely, that individuals differ widely by original nature and\nthat similarity in conditions of nurture and training will not avail in\ndeleting these differences.\n\nGalton and others, from extensive studies based on English sources, have\nshown that notable achievements have run in certain families to a degree\nthat is inexplicable on the basis of opportunity alone; it can be fully\naccounted for only by attributing much to superior inborn capacity. Doctor\nWoods has shown much the same thing for certain families in America.\nSchuster and Elderton have proved that there is a high degree of\nsimilarity in scholastic standing between fathers and sons in Oxford.\nProfessor Pearson's measurements of mental characters in brothers and\nsisters while at school show a high degree of innate resemblance in many\ncases and certain cases of decided contrast. Where contrasts exist in\ncertain families they remain unreduced in spite of the similarity of\nenvironment, thus proving that environment is less operative in the final\nintellectual establishment of such individuals than are their inborn\naptitudes. Even in twins, as both Galton and Thorndike have shown, there\nis no tendency for similar education, home life and the like to render\nthose originally different any more similar with advancing years.\n\nProfessor Karl Pearson has done more perhaps than any other individual\ntoward attempting actually to measure the relative strength of heredity\nand environment. Numerous statistical measurements lead him to conclude\nthat it is a conservative estimate to regard heredity as at least five or\nten times as important as environment in the development of the\nindividual. A vigorous defense by him of this position will be found in\n_Biometrika_ for April, 1914.\n\n=Inter-Racial Marriage.--=Some of the dangers of racial deterioration\nwhich threaten us because of our laxity regarding immigration have already\nbeen indicated. It is high time that we give this whole question the most\nserious consideration of which we are capable. From the rate at which\nimmigrants are increasing it is obvious that our very life-blood is at\nstake. For our own protection we must face the question of what types or\nraces should be ruled out. Aside from the dangers which lie in the\ndefective or unsuccessful types already discussed in Chapter IX, many\nstudents of heredity feel that there is great hazard in the mongrelizing\nof distinctly unrelated races no matter how superior the original strains\nmay be. Unfortunately there is a great lack of reliable data on this\npoint. The mulatto of our own country, the Eurasians in India and the\nmixed races of South America are, according to the testimony of many\nobservers, eloquent arguments against such hybridization. Agassiz remarked\non this point as follows:\n\n    \"Let any one who doubts the evil of the mixture of races and who is\n    inclined from mistaken philanthropy to break down all barriers between\n    them come to Brazil. He can not deny the deterioration consequent upon\n    the amalgamation of races, more wide-spread here than in any other\n    country in the world, and which is rapidly effacing the best qualities\n    of the white man, the Indian, and the negro, leaving a mongrel\n    nondescript type deficient in physical and mental energy.\"\n\nOf the American mulatto one not infrequently meets with the assertion that\nhe is on the average inferior mentally, morally and physically to either\nthe white or the negro race. Thus Doctor J. B. Taylor[17] states that,\n\"It is demonstrated by well-attested facts that these hybrids of black and\nwhite are vastly more susceptible to certain infections; their moral as\nwell as physical stamina is lower than that of either original race.\"\nOthers would deny that conclusive evidence to this effect exists. However,\nit is certain that under existing social conditions in our own country\nonly the most worthless and vicious of the white race will tend in any\nconsiderable numbers to mate with the negro and the result can not but\nmean deterioration on the whole for either race.\n\nThere is certainly not one iota of evidence that the crossing of any two\nwidely different human races will yield superior offspring in any respect\nand there are many indications that such intermixture lowers the average\nof the population. Our evidence derived from plant and animal breeding is\nalso against pronounced crosses. The inferiority of the mongrel is\nuniversally recognized. No sane farmer, for example, would seek to improve\nhis Jerseys or his Herefords by crossing one with the other. It is true\nthat in pure breeds of plants and animals we sometimes venture on a cross\nto introduce some new desirable character but we follow up such mixture by\na rigid selection in which is eliminated all but the rare individuals\nhaving the desired characteristics, and we continue this elimination\ngeneration after generation to fix our characters again. It is obvious\nthat no such selection as this would be possible among the progeny of\nhuman crosses.\n\nIt clearly becomes our duty then to determine as accurately as possible\nthe degree of non-relationship between races it is inadvisable to\ntranscend in inter-racial marriages. We are certainly taking great risks\nin accepting in any considerable numbers those races we can not assimilate\nto advantage into our own stock.\n\n=War.--=The deteriorating effect of war on national physique and vigor has\nbeen so frequently cited by eugenists[18] and is so obvious as scarcely to\nrequire further comment. It should be pointed out, however, that where, as\nis the case at present in Great Britain, armies are assembled from\nvolunteers, instead of by conscription, there is the greatest danger from\nthe eugenic standpoint, since not only physical but moral qualities are\ninvolved. For it is the brave, the generous, the individual with a high\nsense of duty who goes forward to the slaughter leaving the cowardly, the\nselfish or the indifferent to father the race. With the awful deadliness\nof modern warfare upon exhibition before our very eyes to-day, the extreme\nseriousness of such selective action must be evident to every thoughtful\nperson.\n\n=Human Conservation.--=We talk much in recent years of _conservation_; but\nwhat are our forests and frontiers, our minerals and our waterways,\ncompared with our national health and life-blood? No farmer would think of\nsetting aside a diseased or physically defective _animal_ for breeding\npurposes, yet the same man together with the majority of mankind is wholly\noblivious to similar faults when it comes to the mating of human beings.\nBut is it not as important to look to fitness in man as in Poland China\nhogs or Holstein cows? Certainly the various strains are as marked and\nbreed as true in the human family as in our live stock. Why face\ncomplacently in our own families what we would not tolerate in our\npiggery?\n\nFrom the expenditure of comparatively small sums in studying the\ninheritance of various qualities in wheat, corn and other grain,\nimprovements based on the laws of genetics have been secured which are\nenormously increasing our agricultural output and thereby adding to our\nnational wealth. But if it costs relatively little to discover and\nconserve millions of dollars' worth of hereditary qualities in our plants\nand animals, what are we to think of ourselves, an intelligent people who,\nknowing that \"every good tree bringeth forth good fruit, but a corrupt\ntree bringeth forth evil fruit,\" still go on placidly permitting the\nproduction of defectives and delinquents? Can we continue to drink the\nsluggish blood of the pauper and the imbecile into our veins and hope to\nescape unscathed?\n\nWe are all familiar with the fate of Babylon, Assyria, Persia, Egypt and\nRome. Why not America? Certainly we have no pledge of special immunity\nfrom Divine Powers. If so, what then is the meaning of our 366 hospitals\nfor insane which cost us annually $21,000,000; our 63 institutions for\nfeeble-minded costing us over $5,000,000; our 1,300 prisons maintained at\na cost of more than $13,000,000; our 1,500 hospitals whose annual\nmaintenance requires at least $30,000,000; our 115 schools or homes for\ndeaf and dumb; our 2,500 almshouses with an annual expense account of\n$20,000,000 and our 1,200 refuge homes costing annually several millions\nof dollars more? To say that we spend annually over $100,000,000 on the\ncustody of insane, feeble-minded, paupers, epileptics, deaf, blind and\nother charges is expressing the situation very conservatively.\n\n=Kindness in the Long Run.--=There is no one I think who will not admit\nthat the sympathy and charity of the human heart are its noblest virtues.\nBut we must face the problem of what is kindness in the long run. Havelock\nEllis well says, \"The superficially sympathetic man flings a coin to the\nbeggar; the more deeply sympathetic man builds an almshouse for him so\nthat he need no longer beg; but perhaps the most radically sympathetic of\nall is the man who arranges that the beggar shall not be born.\"\n\nWhat shall we do?\n\n=The Problem Has Two Phases.--=For an intelligent consideration of the\nproblem one must recognize at the outset that it has two distinct phases;\nnamely, (1) a selective union of the fittest, or in other words, a\nconscious attempt to breed a superior race; and (2) the elimination of the\nobviously unfit by preventing their reproduction, with the purpose of\npurifying the present race. It is evident at a glance that these are two\nessentially distinct problems although the practise of either method could\nresult in racial improvement. The first is sometimes spoken of as\n_positive_ or _constructive eugenics_, the second as _negative_ or\n_restrictive eugenics_.\n\n=Constructive Eugenics Must Be Based on Education.--=As to the first\nphase, direct selection for superiority, the campaign must, in the very\nnature of things, be one of education. With the necessary knowledge of the\nfacts in mind, the awakening conscience of the individual together with\nan enlightened public opinion will form the safest guide. Increasing\npopular comprehension of the inevitable nature of human inheritance must\nengender a sense of responsibility as to the positive eugenic fitness of a\ncontemplated marriage. The growth of this sentiment will doubtless be\nslow, and properly so, for as yet we have but half-lights on what are the\nmost desirable types of humanity. No one can say what the highest type of\nman should be, but almost any one can readily pick out types which\ncertainly should _not_ be.\n\n=Inferior Increasing More Rapidly Than Superior Stocks.--=Modern\neugenists, although realizing that the constructive phase is of great\nimportance, are making no attempt to map out any fixed mode of procedure\nfor it beyond pointing out the desirability of larger families among the\nbetter classes. The need for individuals of superior physical, mental and\nmoral qualities to multiply is so obvious as scarcely to require comment.\nYet the fact is that judging from all appearances these are the very ones\nwho have the lowest birth-rate. Eugenics is mainly concerned with the\nrelative rates of increase of the various classes, not with mere fertility\nin itself. And the actual increase must be measured in terms of the extent\nto which birth-rate exceeds death-rate. If a high birth-rate is\naccompanied by a high death-rate then it is not especially significant in\nincreasing a given class as a whole. All available evidence points to the\nfact that to-day the lower strata of society are far outbreeding the\nmiddle and higher, with an almost negligible difference in death-rate, and\njust in the measure that these lower strata are innately inferior just in\nthat degree must the race deteriorate. The seriousness of the whole\nsituation as it exists to-day hinges, therefore, on the extent to which\nthe lower strata are inferior to those above them.\n\n=An Unselected Population May Contain Much Valuable Material.--=In\nevaluating these lower strata a matter of very great importance is whether\nthe population is a selected or an unselected one. If the population has\nbeen long resident in a given region and has had fairly good opportunity\nfor education then we will find in the lower reaches a larger percentage\nof sedimentation made up of the worthless and inferior stocks. If,\nhowever, a continual fomentation and geographical shifting of the\npopulation is in progress as in parts of America, or if adequate\neducational opportunities are lacking, as in some parts of Russia, the\npoor and less well-to-do classes may contain, no one can tell how much,\nrelatively valuable stock.\n\nForel remarks on this point as follows:\n\n    \"If we compare the nature of delinquents, abandoned children,\n    vagabonds, etc., in a country where little or nothing has been done\n    for the people (Russia, Galicia, Vienna, etc.), with that of the same\n    individuals in Switzerland, for example, where much has already been\n    done for the poor, we find this result: In Switzerland, these\n    individuals are nearly all tainted with alcoholism, or pathological\n    heredity; they consist of alcoholics, incorrigibles, and congenital\n    decadents, and education can do little for them because nearly all\n    those who have a better hereditary foundation have been able to earn\n    their living by honest work. In Russia, Galicia, and even in Vienna,\n    we are, on the contrary, astonished to see how many honest natures\n    there are among the disinherited when they are provided with work and\n    education.\"\n\n=The Lack of Criteria for Judging Fitness.--=Barring the untold hordes of\nactual defectives who have gravitated into this lower stratum, there are\nfew positive criteria by which we can measure the real fitness of the\nremainder. Before we can set out on a campaign of positive eugenics we\nmust have some standard by which to steer, and it would be a rash advocate\nindeed who would assert that class distinction alone, or even success as\nmeasured by public opinion to-day should be our whole criterion of\nfitness. Shall we measure fitness in terms of how successfully one can\nacquire worldly goods, or in other words, by the property test, or what\nshall be our standard?\n\n=The College Graduate.--=Many of our modern critiques of the birth-rate\nsituation make much of the fact that our college graduates as a group are\nscarcely reproducing themselves. According to Davenport, Bryn Mawr College\nbetween 1888 and 1913 has graduated 1,193 bachelors of arts, but these\nwomen have produced up to January, 1913, only 263 girls to take their\nplace in the next generation. He also points out that statistics on some\nof the graduate classes of Harvard of twenty years ago or earlier show\nthat they are little more than maintaining themselves; thus one class of\n328 graduates twenty years later had produced 195 sons, and in another\ncase a class of 278 individuals had produced, twenty-five years later, 141\nsons. Relatively similar statistics can be cited for other eastern\ncolleges.\n\nAll such cases of college graduates cited as especially deplorable\ndeclines in birth-rate are based on the assumption that these individuals\nare a particularly superior stock.[19] But one might question this premise\nas a generalization. It may or may not be true. Are they superior or have\nthey had mainly a combination of luck and incentive, luck in that their\nparents had sufficient means, acquired possibly through their own\nsuperiority, possibly not, to send them to college, and incentive derived\nfrom a fortunate environment which awakened a desire in them--or in their\nparents for them--for college education? Is the woolly-witted son of\nopulence, so abundant in our colleges to-day, who is boosted through by\nhook or by crook, of superior eugenical value to the alert eager boy--and\nhis name is legion--destined for economic reasons to go to work at or\nbefore the completion of his high-school course, perhaps because of the\nvery fact of an unlimited fecundity in his own family which necessitates\nhis help for the general support?\n\nWhen one first learns of the declining birth-rate among college women and\nmen he feels appalled, but immediately the question flashes up, if this is\n_the_ superior stock, and up to date it has died out or is dying out\nrapidly, whence then this ever augmenting rush of young folk who fairly\ndeluge our universities and colleges to-day? Does it not rather point to\nthe fact that in our own country at least, the man who will and can take\na college education successfully is not so much the product of breeding\nfrom college men, but of a prosperity which leaves a sufficient surplus in\nthe family exchequer to enable sons and daughters to go to college, and is\nit not reasonable to suppose that there is yet an abundant stock back of\nthese who similarly await but the golden touch of opportunity? When we\nconsider such men as Carlyle, Lincoln and a host of others who were not\nthe sons of collegians, although we may be university pedigreed ourselves\nwe can not but feel doubtful of the validity of a premise which takes a\ncollege stock unqualifiedly as having any considerable monopoly of innate\nsuperiority. After all, college can mean little more than opportunity, and\nthe obtaining of such opportunity in this world of economic maladjustments\nand accidents of social position is too largely a matter of chance, at\nleast in America, to stamp the possessors of these advantages, on this\ncriterion alone, as of inborn superiority. Undoubtedly much that is\nintrinsically good now slumbers in the lower strata of society because of\nlack of favorable environment to call forth the latent possibilities.\n\n=Native Ability, Independence and Energy Eugenically Desirable.--=Although\nwe can not sift out with certainty the superior from the inferior in our\nnormal population by the property test or the educational standard alone,\nit is undoubtedly true that, on the whole, native ability, independence\nand energy are present to a higher degree in our well-to-do and prosperous\nfamilies than in the stocks which merely hold their own or which\ngradually decline, and there is no gainsaying the fact that in so far as\nthe lower classes are where they are through actual deficiency--and there\nare enormous numbers in this category--they threaten our very existence as\na race. It is imperative that the great middle class in particular\nestablish in some way a selective birth-rate, by increased fertility on\ntheir own part, and diminished fecundity on the part of inferior stocks,\nwhich will offset or more than offset the disproportionate increase of the\nsocially unfit.\n\n=Four Children to Each Marriage Required to Maintain a Stock.--=It is\nestimated that under present conditions an average of at least four\nchildren should be born to each marriage if a stock is to maintain its\nnumbers undiminished. Some of our most valuable strains are falling far\nshort of this average. In a statistical table on the relative fertility of\ndifferent stocks, prepared by Pearson, we find the mentally defective,\ncriminal, deaf-mute and degenerate stocks heading the list with averages\nranging from five to seven children per family, while the American\ngraduate (based on Harvard statistics) and the English intellectual types\naverage less than two children per marriage. While the death-rate is\nhigher in the undesirable classes mentioned, it is by no means enough\nhigher to compensate for the difference in birth-rates. Thus while certain\nvery desirable types are not maintaining themselves genetically, other\nextremely undesirable ones are rapidly more than replacing themselves.\nInvestigations made by Heron in London show that this condition as regards\nEnglish desirables did not exist sixty years ago; then the richer a\ncommunity was in professional men and well-to-do families, the higher was\nthe birth-rate.\n\n=Factors Contributing to Low Birth-Rate in Desirable Strains.--=Most\nstudents of the subject believe that the fecundity of much of the best\nblood in our country has reached such a low ebb as to threaten the whole\nfabric of our commonwealth. How to correct this is the pressing problem to\nwhich no one has found a solution. However much one may deplore it the\nfact remains that always in the history of the civilized world with the\nrise of material conditions in any class of a population there has come an\naccompanying limitation of child-birth. Explain this as we may in modern\ntimes--whether as an awakened individualism which looks only to the\nimmediate interest of the individual as against the ultimate interest of\nthe race, or a desire for luxuries or for a better opportunity for smaller\nnumbers of children, or as a determined effort of the wage earner to\nbetter his conditions, or to the feminist movement with its accompaniment\nof a greater personal freedom of married women and the recognition of the\nfact that marriage and child-bearing are often bars to employment, or to\ngeneral increasing pressure of economic burdens--in brief whatever the\ncause or causes, there is no denying the fact of a diminishing birth-rate\namong our abler men and women. Moreover, no amount of coaxing, cajoling or\ndire prophecy seems to avail in altering the conditions. Various partial\nremedies, many of them of questionable practicability, have been proposed,\nbut so far there has been no far-reaching effort made to put any of them\ninto effect. It has been suggested that society return to the simple life\nso that our young folk may marry earlier and live more easily on limited\nmeans, but so far few volunteers have appeared to lead the procession.\nWhile there is no doubt that present economic conditions tend to penalize\nparenthood, the simple life will not return for the mere asking. It has\nbeen pointed out that the father is in unfair competition with the\nbachelor and is also unfairly taxed in comparison, and some would\ntherefore tax unmarried men more heavily. Others would pay a direct bounty\non reproduction, but it is probable that such rewards would merely\nstimulate families of the lower types to increased fruitfulness. And so\none panacea after another may be weighed and found wanting.\n\n=The Educated Public Must Be Made to Realize the Situation.--=It seems\nprobable that the most success will be met with through the slow and\nunspectacular methods of education. The necessity of the situation must be\ndriven home so that it becomes part and parcel of the collective\nintelligence of the educated public. Different ideals of life will have to\nbe established in the young. If knowledge of the facts of heredity is\nthoroughly disseminated among the people and ideals regarding parenthood\nare fostered, then much will have been accomplished by the psychic power\nof suggestion alone toward the end desired.\n\n=Utilization of Family Pride as a Basis for Constructive Eugenics.--=There\nare few more powerful incentives to make the best of one's abilities, or\nfew greater deterrents from vice than family pride; and there is no\nreason why this same sentiment may not be aroused in behalf of unborn\ngenerations. The sentiment of caste or aristocracy in some form is well\nnigh universal in mankind. The family of Mr. A came over in the Mayflower\nand is therefore worlds above the family of Mr. B, who arrived fifty years\nlater. Mr. X's income is $5,000 a year, Mr. Y's only $1,500. The poor\nfamily in the front suite of the tenement regards itself as far superior\nto the one in the rear. Among criminals the professional house-breaker\nfeels himself to be of higher caste than the sneak-thief, and in turn is\nsurpassed by the bank-burglar. Even in the insane asylum the feeling is\nrampant. With such a wide-spread tendency for a foundation the creation of\na sentiment of eugenic aristocracy is by no means a visionary undertaking.\n\n=The Tendency for Like to Marry Like.--=Even now there is a decided though\nunconscious tendency for like to marry like and thus create particular\nstrains. We have lines, for instance, which produce notably families of\nscholars, others which yield mainly statesmen, and still other strains of\ninventors, of financiers, of naval men, of soldiers, and of actors\nrespectively. And there is little doubt that people, with the facts of\ninheritance of ability once before them, will be led to act more or less\nin accordance with their knowledge. On the other hand, due apparently to\nthe same unconscious tendency for like to marry like, we find produced\ncriminalistic, feeble-minded, deaf-mute and tubercular stocks. The first\ntype of family is often termed _aristogenic_ and the second or defective\ntype, _cacogenic_.\n\n=Public Opinion as an Incentive to Action.--=Much of our social conduct is\nthe result of the pressure of public opinion, yet so accustomed are we to\nthis that we ordinarily do not feel it as a hardship. There is little\ndoubt that similarly the more wholesome attitude toward parenthood\nadvocated by the eugenist would be taken as a matter of course, once the\nidea became prevalent. It would come to be one of those socially\npreconceived ideas which are as much actualities and which become\nunconscious guides to action no less certainly than do the more obvious\npersonal habits of the individual. And just in the degree that we as a\nrace get the \"feeling\" that intellect, morals and skill are highly\ndesirable attributes in marriage selection, just in that degree will one's\naffections in their earlier stages gravitate toward individuals who\npossess such qualities in high degree. In the main, those stocks which\nhave shown by ancestral as well as personal achievement their superiority\nwill tend to insure most certainly a continuation of this superiority in\noffspring.\n\n=Choosing a Marriage Mate Means Choosing a Parent.--=Although marriages,\nas all young folks know, are made in Heaven, it is interesting to see what\na vast number of these foreordained matches coincide with propinquity in\ncollege, in church, or in the same social set. Moreover, children are born\nhere on earth. The one thing of all things that the eugenist desires is\nfor these young folk to get a clear-eyed vision of the fact that in\nchoosing a marriage mate they are also choosing the future father or\nmother of their children with all that this implies.\n\n=The Best Eugenic Marriage Also a Love Match.--=A few recent writers, who\nshow an utter misconception of what the aim of modern eugenics is, have\nraised the cry of give us the old-fashioned love match instead of the\neugenic marriage, as if the eugenist's ideal of moral cleanliness, freedom\nfrom transmissible physical taints or mental enfeeblement, and an attitude\nof special approval toward marriages which bring together individuals of\nmore than average mental or spiritual endowment, had anything in it that\nwas inimical to love. No one better than he realizes the sordid depths to\nwhich marital relations devoid of mutual affection and regard must reach.\nCertainly there is nothing in the eugenic ideal when its full import is\nunderstood that can shock the sensibilities of the most delicate-minded.\nIndeed it is people of fine susceptibilities who will be the first to feel\nrepugnance toward a marriage which means mental or physical deterioration\nof their own blood.\n\n=Good Traits No Less Than Bad Ones Inherited.--=An inspection of such\ncharts as those shown in Figs. 37, 38 and 39, pp. 313, 314, 316--and an\nabundance of such encouraging records may now be found--reassures us in\nour convictions that good traits are no less inheritable than bad ones.\nAnd what any healthy, mentally well-endowed person may be depriving the\nworld of if he or she declines to enter into a fruitful marriage can not\nbe better exemplified than in the following excerpt from Davenport:\n\n    \"Many a man at the opening of his life work vows, as Judge John Lowell\n    of the middle of the eighteenth century did, as he was being graduated\n    from Harvard College, that he will never marry. But nature was too\n    strong for John Lowell and he married three times, and among his\n    descendants was the director of a great astronomical observatory, the\n    president of Harvard College, a principal founder and promoter of the\n    Massachusetts General Hospital and the Boston Atheneum; the founder of\n    the city of Lowell and its cotton mills; the founder of the Lowell\n    Institute at Boston; the beloved General Charles Russell Lowell and\n    his brother, James, both of whom fell in the Civil War, and James\n    Russell Lowell, poet, professor and ambassador; besides brilliant\n    lawyers and men entrusted with large interests as executors of\n    estates. Do you think John Lowell would have taken that vow could he\n    have foreseen the future?\"\n\n\n[Illustration: FIG. 37\n\nPedigree of family with artistic (dark upper section), literary (dark\nright section) and musical (dark left section) ability (from Davenport).]\n\n\n=The Elimination of the Grossly Unfit Urgent.--=But even if, under present\nconditions of partial knowledge and lack of an adequate standard, the\nconstructive phase of eugenics must be left in the main to the awakening\nconscience of the individual as humanity improves in general\nenlightenment, the second phase, the elimination of the grossly unfit is\none of the greatest social obligations that confronts us to-day. For if\nthere is an alarming amount of mental impairment in civilized nations, and\nif the problems of pauperism, inebriety, prostitution and criminality are\nclosely interwoven with the problems of mental unsoundness, as we have\nevery reason to believe from available data, then any means which will\noperate toward securing normally functioning brains will at the same time\noperate toward diminishing, defects and delinquencies. And inasmuch as a\nconsiderable proportion of defects, both mental and physical, are\ninheritable, it is obvious that if we can diminish the number of children\nborn into the world with defective brains or bodies we have made a long\nstride in the right direction.\n\n\n[Illustration: FIG. 38\n\nInheritance of ability (from Kellicott after Whetham).]\n\n\n=Suggested Remedies.--=But how go about it? Various schemes have been\nproposed, of which the chief are as follows:\n\n    1. Laws restricting marriage.\n\n    2. Systems of mating with the purpose of covering up and gradually\n    diluting out defective traits.\n\n    3. Segregation during the reproductive period.\n\n    4. Sterilization.\n\n    5. Education in the principles of eugenics.\n\n=Inefficacy of Laws Which Forbid Marriage of Mental Defectives.--=The\nutter inefficacy of the first proposition, namely the enactment of laws\nrestricting marriage, at least as regards the socially unfit whose\ncondition is based on impaired mentality, has been demonstrated time and\nagain. If they are forbidden marriage, they merely have children without\ngetting married. Most states have laws to prevent the marriage of such\nindividuals but these laws are almost wholly ineffective in preventing\nprocreation on their part. We might as well recognize once for all that in\nsuch cases nothing short of close custodial care or sterilization will\naccomplish the end desired.\n\nAs to the second proposition, systems of mating with the purpose of\ncovering up and gradually diluting out defective traits, this has been\nshown to be possible with certain types of defectives. Whether it is\ndesirable or not is a different question.\n\n\n[Illustration: FIG. 39\n\nInheritance of ability (chart condensed and incomplete) in three markedly\nable families (from Kellicott after Whetham):\n\n1, Charles Darwin; 2, his cousin, Francis Galton, founder of the modern\neugenic movement.]\n\n\n=Systems of Mating Impracticable in the Main.--=By systems of mating, it\nshould be said, is not meant the arbitrary marrying of two individuals\nwilly-nilly, but rather it is the prevention from marriage of two\nindividuals having similar defects. In general the facts at our command\nindicate that in the majority of cases the offspring from a marriage of an\ninsane, feeble-minded or epileptic person with a normal individual free\nfrom all neuropathic taints are normal or at most show but slight effects\nof the taint. But what normal individual would knowingly marry into such a\nstock? With few exceptions such traits where inheritable are apparently\nnegative, that is, not represented by some positive abnormal factor but\ndue to the lack of some element or elements necessary to the proper\nworking of the normal brain. In the offspring of such a union the\nnecessary missing factors are supplied by the normal parent. Or in\nMendelian phraseology, the defective traits are recessive and are\ndominated by the normality of the other parent. Such offspring, however,\nwhile apparently normal of body are not normal of germ-plasm, inasmuch as\nhalf of their germ-cells will carry the abnormality of the defective\nparent as earlier explained (page 119) under Mendelism. We have already\nseen (page 119) how by continually marrying into strong strains the\nliability to recessive defect can be diluted out until the descendants are\nno more likely to have defective children than are members of our ordinary\npopulation. If, however, as is estimated in Bulletin No. 5 of the\n_Eugenics Record Office_, about thirty per cent. of our general population\nalready carry recessive neuropathic taints, it certainly is a hazardous\nproceeding to attempt thus to breed out nervous defects unless one is\nabsolutely sure of the normality of the strain into which it is proposed\nto marry. The great difficulty is in determining whether or not there is a\ndefective ancestry in a given stock. We have at present no criteria for\nidentifying normal individuals who have defective germ-plasm. As a\npractical test, however, if no defect has appeared in the stock for three\nor four generations back, the marriage would be relatively as safe as are\nthe marriages of our average population to-day.\n\n=Corrective Mating Presupposes Knowledge of Eugenics.--=But such a scheme\nof corrective mating presupposes a relatively high degree of intelligence\nand judgment on the part of the participants, and this is just what we do\nnot have and in the nature of things can not get, in the types of\nfeeble-minded, epileptic and degenerate strains we are striving to\neliminate. All our evidence shows that when unrestricted there is a marked\ntendency for feeble-minded to mate with feeble-minded, degenerate with\ndegenerate. About sixteen per cent. of the feeble-minded, in fact, come\nfrom consanguineous marriages. If we try to legislate them into specific\ntypes of marriage then we encounter the same futility pointed out under\nour discussion of restrictive legislation, they will produce offspring\nwithout the formality of marriage.\n\nIn certain cases of insanity and in other than neuropathic defects one can\nsee how the system might be inaugurated with greater prospects of success,\nbut even then a knowledge of the principles of eugenics would be necessary\nto the participants, or in other words we could only accomplish our end\nthrough our fifth proposition, education.\n\n=Segregation Has Many Advocates.--=As to the third proposition,\nsegregation during the reproductive period, this seems to have a larger\nnumber of advocates than any other coercive measure. While on theoretical\ngrounds it is plausible enough, when we face the actual putting of the\nmethod into practise we are confronted by the fact that tremendous sums of\nmoney would be required to sequestrate and maintain colonies or industrial\nrefuges.\n\nWhen one realizes that no state now provides for more than a small\nminority of its defectives, and knowing also of the pressure that must be\nbrought to bear on legislatures to secure sufficient funds to provide for\nthese cases of extremest urgency, one can not be overly optimistic about\nthe practicability of extensive sequestration.\n\nE. R. Johnstone, the superintendent of a large training school for\nfeeble-minded in New Jersey, points out that no state in the Union is\nproviding for many more than one-tenth of her feeble-minded and\nepileptics. If his estimate is true, to place in institutions, treat and\ntrain all its feeble-minded and epileptics would even now almost swamp any\nstate treasury. But what _will_ it be in the future if we permit this\nunrestricted nine-tenths to go on and multiply their kind?\n\nLeaving out of account the enormous sums spent in private charities even\nnow from one-fifth to one-seventh the total public expenditures of almost\nany one of our states is going to maintain its defectives, dependents and\ncriminals. From the 1912 report of the secretary of state, in the state of\nWisconsin, for instance, I learn that of the total expenses for 1912,\nsixteen per cent. was for charitable and penal institutions. The situation\nis even worse in some other states. Think of it! Think what a large total\nof expense it becomes! And the expense is far secondary from the\nhumanitarian standpoint to the misery involved.\n\nIn the _Survey_ of May 24, 1913, we find Mr. Hastings H. Hart, Director of\nthe Department of Child Helping of the Russell Sage Foundation, proposing\nvery specifically \"a working program for the extinction of the defective\ndelinquent,\" which involves segregation during the reproductive period. He\ngives the number of feeble-minded under public care as 20,000 in\ninstitutions for the feeble-minded, 16,000 in almshouses, 5,000 in\nhospitals for the insane, and 26,000 in prisons and reformatories, or a\ntotal of 67,000 already under custodial care. And he asserts that as\nnearly as can be judged, this is one-third of the feeble-minded persons in\nthe United States.\n\nBetween this estimate that one-third of our feeble-minded are in\ninstitutions and Doctor Johnstone's that we are not providing for many\nmore than one-tenth of our feeble-minded and epileptic, there is a wide\ndiscrepancy, but I know of no accurate data[20] whereby the matter can be\nsettled definitely. One point of difference may be that Doctor Johnstone\nspecifically includes epileptics and another may be one of definition of\nfeeble-minded. However, supposing that we could get them all into\ninstitutions, institutional care at present by no means also implies\nprevention of propagation. It is not an unusual history of feeble-minded\nwomen in our county poor-houses that they alternate between periods of\nhousework in some family and periods of residence in the almshouse, the\nreturn to the latter being only too often to bear an additional child.\n\nNot a few students of the problem, however, advocate a rigid segregation\nas the only reasonable preventive measure, no matter what the expense.\nThey point out that the cost is mounting up higher each year and that we\nare only increasing it ultimately by procrastination. They urge, moreover,\nthat when counting the cost of the segregation of the feeble-minded we\nshould bear in mind also that we are reducing the expenses of our other\ncharity and penal institutions, since much of degeneracy, pauperism and\npetty criminality centers in mental enfeeblement. Some believe that\ncolonies can be established which are in considerable measure\nself-supporting. Doctor Johnstone, for instance, although his estimates of\nthe number of feeble-minded and epileptic is one of the highest, sketches\nout in a recent paper (in _Pediatrics_, August, 1912) a plan which he\nconsiders feasible.\n\nBut what assurance have we that we can prevent the production of\ndefectives by segregation? In reply may be cited a recent experiment on an\nextensive scale. Cretinism is a condition due to disease of the thyroid\nglands. It is characterized by goiter, marked deformities and imbecility.\nIt is hereditary and has been very prevalent in certain valleys of\nsouthern Switzerland and northern Italy. Cretin mated with cretin and\nconsequently a large new supply was constantly produced. In recent years\nin certain communities the sexes have been segregated (see _Eugenic\nReview_, 1910, Jordan) with the result that in such places cretinism has\nabout disappeared.\n\nComing now to the fourth solution proposed, namely, sterilization,[21] let\nus consider some of its alleged advantages and disadvantages.\n\n=Sterilization.--=First of all, since there is some considerable popular\nmisunderstanding on the subject, it should be made plain that by\nsterilization is not necessarily, nor in fact generally, meant\nasexualization, or the removal of the reproductive glands. On the\ncontrary, in the male, sterilization is ordinarily accomplished by an\noperation known as _vasectomy_, in which a small piece of each sperm duct\nis removed. Such reports on it as I have found indicate that it is a\ncomparatively simple minor operation which involves no special\ninconvenience or hardship on the subject beyond the deprivation of\noffspring. In fact, according to Doctor Sharp's report, in the majority of\ncases where it has been put into practise the patient has usually\nsubmitted voluntarily after having the details of the situation explained\nto him and has often advised fellow delinquents to do likewise.\n\nEven should later developments show that a mistake had been made, in all\nprobability the matter could be remedied by a second operation in which\nthe cut ends of the ducts can be reunited. This has been accomplished\nexperimentally in dogs, and furthermore, in men rendered sterile by\nocclusion of the duct through inflammatory diseases, the sterility has\nbeen remedied by removing the blocked area and reuniting the ends of the\nduct on either side.\n\nIn women the corresponding operation--a section of the oviduct--is termed\n_salpingectomy_. Here, however, the operation is a more serious one as it\nusually involves opening the abdominal cavity and the accompanying hazard\nof infection, a danger sufficiently great that it is safe to say that the\noperation will be resorted to more rarely than vasectomy in man.\n\n=As a Eugenic Measure.--=Sterilization as a eugenic measure has many\nadvocates and perhaps more opponents; and among the latter, it must be\nsaid, are many competent and thoughtful students of the subject who\nrecognize existing conditions and deplore their continuance as much as any\none. They maintain that while we may have to come to it as a last resort,\nwe are yet too ignorant of the actual effects of the operation, or are too\nlittle informed on the inheritability of the specific traits we are trying\nto eradicate, to launch forth on so radical a program. We must not forget\nthat when we put sterilization into effect we are going to have to deal\nwith individual cases, not general averages.\n\n=To What Conditions Applicable.--=And just here, it seems to me, is the\ncrux of the situation. When confronted by the defective individual, in a\npractical case, just what criteria are we going to use to determine\nwhether this particular individual should be sterilized or not? Nearly all\nof the twelve states which have sterilization laws specify insanity,\nfeeble-mindedness, epilepsy and criminality.\n\n=In Insanity.--=When it comes to insanity I strongly suspect that those\nwho have the selection of the examining board will have difficulty in\nfinding an alienist who is willing to take the responsibility of deciding\non just which insane individuals shall be operated on and which not. For\namong the insane there are so many kinds and degrees of mental\nunsoundness, and these are of such varying and as yet unknown eugenical\nsignificance, that a positive decision is frequently out of the question.\nOf the twenty-seven or more recognized forms of insanity who knows with\nany considerable degree of certainty which are heritable, which not? Shall\nwe treat all manic-depressives alike? Shall we treat them as, for\ninstance, we would those suffering from dementia precox? Who will take the\nresponsibility of answering positively? Again, what shall we do in cases\nof paresis, or general paralysis of the insane, an affliction which\nprobably invariably has syphilis as its antecedent? Yet it constitutes one\nof the commonest forms of insanity found in asylums. Doctor George H.\nKirby, director of Clinical Psychiatry, Manhattan State Hospital, says\nthat with one exception there are more admissions of paretics to Manhattan\nState Hospital than sufferers from any other form of mental disorder. He\ncontinues, \"We find that when either the father or the mother suffers from\nparesis that many other members of the family may be infected with\nsyphilis, and furthermore, we find that a surprisingly large number of\nchildren in these families are feeble-minded, nervous, or in other ways\nabnormal.\" But here, it is clear, the patient has done the damage before\nhe reached the hospital, nor was it paresis as such that did the harm but\nthe syphilitic infection of which paresis itself was but the outcome.\n\nCertainly the one fact which stands out conspicuously when we face most\nconcrete cases, is that at present we need more urgently than\nsterilization laws for the insane, exhaustive studies of the\ninheritability of specific mental infirmities that we may know with some\ndegree of certainty which warrant sterilization.\n\nYet on the other hand one of the most disquieting facts that confronts us\nto-day is the large number of patients who are on parole from our\nhospitals for the insane, subject to recall. What shall we do with them?\nShall we submit them to the tremendous hardship of still remaining under\ncustodial care although to all intents and purposes sane, or shall we make\ntheir release contingent upon their submission to vasectomy or\nsalpingectomy?\n\nIn a few cases such as Huntington's chorea (Figs. 26, 27, pp. 114, 115) we\ncan proceed with a fair degree of assurance, for we know that this\ndreadful malady is transmitted as a positive trait and that in all\nprobability half of the children of an afflicted individual will inherit\nthe defect. Such patients, if they ever rally sufficiently temporarily to\nleave the hospital, or where encountered outside the hospital should\ncertainly be restrained from procreation. It is questionable if even their\nchildren, though apparently normal, should be allowed to have offspring,\nfor usually the disorder does not manifest itself until middle life and\nthen it is too late to try to prevent its transmission since the affected\nindividual has already probably married and had children. But Huntington's\nchorea is a comparatively rare form of insanity, and one of only a few\nabout which our knowledge as regards its transmissibility is fairly\nsatisfactory.\n\n=In Feeble-Mindedness.--=When we come to institutions for the\nfeeble-minded, however, there seems to be much more unanimity of opinion\namong physicians in charge of such institutions that sterilization would\nbe an effective and satisfactory disposition to make of many cases, if we\nare to release the patients in question from custody. Unquestionably in\ncases of imbecility it is easier than in insanities to pass conclusive\njudgment on the inheritability of the condition in a large class of cases.\nPractically all are agreed that either permanent custodial care through\nthe reproductive period or sterilization should be enforced. Some maintain\nthat such individuals should remain permanently in institutions anyway and\nthat therefore to sterilize them is needless, while others urge that if\nsterilized many capable of making their own living could be freed and\nallowed to do so.\n\nAccording to Goddard the feeble-minded woman is about three times as\nlikely to find a mate as a feeble-minded man, hence it would seem to be of\nmuch greater importance to sterilize the woman than the man.\n\nAgain it might be urged with much justification, that even though\nsterilized, the feeble-minded individual because of lack of self-control\nwill transgress sexually and will thus certainly become a menace to\nsociety in the spread of venereal diseases. If Mr. Hart's estimate is\nanywhere near correct, that there are 60,000 feeble-minded women in the\nUnited States of child-bearing age, and that 13,000 are already in\ncustody, then the task of getting all women of this class into custody is\nnot so insurmountable as would at first appear.\n\n=In Cases of Epilepsy.--=As to epilepsy, I find a very decided difference\nof opinion among physicians. Some consider it, on account of its\napparently strong inheritability, together with the shocking crimes\nperpetrated by epileptic criminal types, one of the most serious menaces,\nwhile others point out that we know nothing of the real cause of epilepsy,\nthat there are all degrees and shades, that it is probably referable to\ndifferent causes in different cases and that no one is able to say what\nthe offspring of any given epileptic will be.\n\nAs to criminal types, here again we face the difficulty of deciding any\nparticular case. Let us suppose that twenty-five per cent. of criminals\nare mental defectives, how shall we sift them out from the seventy-five\nper cent. who are supposed to be eugenically normal? Doubtless in many of\nthe twenty-five per cent. class, the indications of defective mentality\nare sufficiently evident to prevent mistakes, but a considerable number of\nuncertain status must also remain near the border-line.\n\n=Sterilization Laws.--=Although twelve of our states already have\nsterilization laws, only two, Indiana and California, seem to have made\nany active attempt to enforce them. The situation is too new yet in\nWisconsin, Michigan and Pennsylvania for these states to have shown what\nthey intend to do. Although the Indiana law says, \"it shall be compulsory\nfor each and every institution\" to maintain the practise, it has fallen\ninto disuse since 1911, presumably because the governor believed the law\nunconstitutional. It is of interest to see the motive underlying the law\nin various states. In the majority it is purely eugenic. In Connecticut it\nis mainly eugenic though partly therapeutic. In California it is\napparently in part therapeutic, since it is stated as being for the\nphysical, mental or moral benefit of inmates of various state\ninstitutions, and in part punitive and eugenic, since individuals twice\ncommitted for sexual offenses or three times for other crimes are subject\nto the operation.\n\nIn Washington and Nevada the object is purely punitive, the persons\nspecified being habitual criminals and persons adjudged guilty of carnal\nabuse of female persons under ten years of age, or of rape. In these\nstates also the court orders the operation instead of leaving it to the\ndecision of a board of medical experts.\n\n=Social Dangers in Vasectomy.--=It has been urged against vasectomy that\nit will work untold harm because it relieves of the responsibility of a\nprobable parentage. This argument does not appeal to one as very weighty\nas far as the imbecile or other degenerate is concerned, because one of\nthe very traits characteristic of such individuals is lack of any sense of\nresponsibility. By this same token, however, we have a very good argument\nfor sequestration as against sterilization, for the degenerate, even\nthough sterilized, will not be restrained sexually and will be likely to\ndisseminate venereal diseases or commit rape. Furthermore, there will be\nthe temptation to sterilize and liberate certain types that would\notherwise have been kept permanently in custody.\n\n=Our Present Knowledge Insufficient.--=When all is said and done, after we\ntake into account the meagerness of our present knowledge on the subject,\nit is not to be wondered at that many thoughtful students of a\nconservative turn of mind, feel that any considerable practise of\nsterilization is premature. The problem has so many phases, and despite\noccasional bits of positive knowledge, we are yet in such a sea of\nignorance regarding it, that in no field is the good Friar Laurence's\nadmonition of \"wisely and slow; they stumble that run fast,\" needed more\nat present than it is here.\n\nThere is little doubt that in theory the feeble-minded and similar\ndefectives should be sent to institutions and kept there, but the\nimportant practical question is, can this be done? We can have no final\nanswer until it is tried. While the initial expense would undoubtedly be\ngreat, if we could keep our defectives from propagation for a single\ngeneration we could very materially lessen their numbers and in succeeding\ngenerations the expenses of their care would rapidly diminish.\n\nThe one crying need that stands out most prominently in this whole field\nis that of careful investigation of individual cases and specific types of\nmalady, together with an accurate census of conditions as a whole. Our\nknowledge of individual malign heredities is too meager to carry us very\nfar at present. When we have found after adequate investigation in just\nwhich specific types of defects heredity is an important factor--and we\nshall undoubtedly find it to be one in many cases--then we can proceed\nconfidently with sterilization, if it will prove to be more practical and\ndesirable than sequestration.\n\n=Sterilization Laws on Trial.--=It will be of great interest and\ninstruction to see how extensively, in the various states which have\nrecently passed sterilization laws, the experts selected will find it\nexpedient to carry on sterilization, and what criteria they will use in\ndeciding on individual cases. That sterilization can be put into effect is\nindisputable, as may be seen from the fact that several hundred operations\nhave been performed in Indiana. If the board on whom the decision depends\nhappens to be one which feels that many people are likely to distress\nthemselves unduly over the border-line cases, and overlook the fact that\nthere is always a goodly residue with which to proceed without great risk\nof mistake, then we may expect to see a vigorous campaign inaugurated, and\nthose of us who are still undecided in the matter will have an opportunity\nof learning more certainly the merits or the failings of the scheme.\n\nCertain married degenerate types would seem to be the ones most urgently\ndemanding attention. Having already begotten several defective children\nand with nothing else in prospect but the production of the same kind, it\nis difficult to see from any standpoint why a vasectomy on the male would\nnot be a merciful act. There are not a few such families where the father\nis periodically in the hands of the law and yet not in permanent\nrestraint. Once in custody his release could be made contingent on\nvasectomy.\n\n=An Educated Public Sentiment the Most Valuable Eugenic Agent.--=Coming\nnow to the last proposition, education of the public in the principles of\neugenics, this is the method calculated to be of more far-reaching service\nthan any other, in the negative as well as in the positive phases of\neugenics. Education is necessary before we can have effective restrictive\nmeasures for the mentally incompetent established and enforced, and it is\nalso a prerequisite to intelligent procedure on the part of normal\nindividuals in considering their own fitness for marriage.\n\nOf greatest importance in preventing undesirable marriages, as far as\npeople of normal intelligence is concerned, will be the sentiment of\ndisapproval which will arise on the part of society itself when it becomes\nreally convinced that certain marriages are inimical to social welfare.\nPublic opinion is, in fact, one of the most potent influences in marital\naffairs, simply because refusal to abide by the dictates of the community\nmeans social ostracism.\n\nThat social disapproval of certain unions can become a very real factor in\npreventing such marriage is evinced on all sides by the numerous barriers\nto marriage already in existence based on race, religious sect or social\nstatus. Even in our much vaunted democracies one is looked down on who\nmarries \"beneath\" his or her social set. This sentiment of taboo, so\nreadily and often so senselessly cultivated in our present human society,\nwill inevitably spring up in consequence of a wide-spread knowledge of the\nfacts of human heredity. It is to such a growth, to the establishment of a\ndisapproval which is the product of its own sentiments rather than to\nlegislative enactments, that society must look for the greatest\nfurtherance of the eugenic program.\n\nNecessary as legal restraint is in certain cases, it must obviously be\nrestricted to only the most glaring defects. Moreover, legislation can not\nrun far in advance of public opinion.\n\n=The Question of Personal Liberty.--=It must be admitted that there is a\nreluctance on the part of many even thoughtful individuals to the\napplication of methods which savor in any way of restraint. An objection\nnot infrequently urged by such persons against the application of certain\neugenic principles is that they demand an unwarranted curtailment of\npersonal liberty.\n\nTo those who hoist the flag of personal liberty, it may fairly be asked,\nhow much personal liberty does the syphilitic accord his doomed and\nsuffering wife and children, or how much personal liberty is the portion\nof the offspring of feeble-minded parents? Or, what quota of personal\nliberty will accrue to the ill-fated descendants of the epileptic, the\nhabitual drunkard or criminal, the gross moral pervert, the congenially\ndeaf and dumb, or to even the progeny which may result from the union of\ntwo well-established tubercular strains?\n\nWe do not hesitate to send the pick of our stalwart healthy manhood to war\nto be slaughtered by the thousands and tens of thousands when an affront\nis offered to an abstraction which we term our national honor, and,\nsublimely unconscious of the irony of it all, we throw ourselves into a\nwell-nigh hysterical frenzy of protest when it is proposed to stop the\nbreeding of defectives by infringing to a certain extent on their personal\nliberties.\n\nSociety has already found it necessary to suppress certain individuals\nand yet we hear little complaint about loss of personal liberty in such\ncases. But if it is necessary to restrain the man who would steal a purse\nor a horse, is it not still more urgent to restrain one who would poison\nthe blood of a whole family or even of an entire stock for generations?\nSurely there can be but one answer; society owes it to itself as a matter\nof self-preservation to enforce the restraint of persons infected with\ncertain types of disease and of individuals possessing highly undesirable\ninheritable traits, so that perpetuation of such defects is impossible.\n\n=Education of Women in Eugenics Needed.--=One of the most crying needs of\nthe present is the awakening and educating of women to the significance of\nthe known facts. For they are perhaps the greatest sufferers, and once\ninformed, as a mere matter of safety if for no other reason, they will see\nthe necessity of demanding a clean bill of health on the part of their\nprospective mates. Furthermore in the last analysis woman is the decisive\nfactor in race betterment, for it is she who says the final yea or nay\nwhich decides marriage and thus determines in large measure the qualities\nwhich will be possessed by her children. Above all, young women must come\nto realize that the fast or dissipated young man, no matter how\ninterestingly or romantically he may be depicted by the writer of fiction,\nis in reality unsound physically, and is an actual and serious danger to\nhis future wife and children.\n\n=Much Yet to Be Done.--=But plain as is our duty regarding the application\nof facts already known, when we consider that the student of heredity has\nmade only a beginning, it is equally evident that he must be urged on in\nhis quest for new facts, and the establishment of new principles. There is\nimperative need to carry on proper experiments with plants and animals, to\ncollect necessary data regarding man, and for what is scarcely less\nimportant, the publication of the facts already acquired so that the\npublic may be guided aright.\n\nJust at present it is of the utmost importance to secure more trustworthy\nstatistics in order that we may intelligently go about instituting\nsuitable restrictive measures for undesirable human strains. We must know\nthe exact number and kinds of feeble-minded, epileptic and insane in our\npopulation, and we must have more insight into the personal status and\npedigrees of our delinquents and criminals. For purposes of rational\nprocedure such information is indispensable. Much can be done by\nhospitals, \"homes\" and penal institutions by determining and recording\nmore accurately all obtainable facts regarding the ancestry of their\ncharges. Moreover, in such states as Wisconsin, where the state hospitals\nfor the insane have each an \"after-care-agent,\" the duties of such\nofficers might well include the collection of more adequate data regarding\nthe hereditary aspects of their patient's condition. And lastly, if in\nevery census, whether state or national, it were made an important part of\nthe work to secure accurate vital statistics, particularly as they pertain\nto human heredity, the contribution toward enabling us ultimately to\npurge the blood of our nation of certain forms of suffering, degeneracy\nand crime would be inestimably great.\n\n=A Working Program.--=And now after reviewing at some length various\naspects of man's hereditary and congenital endowment, the important\nquestion arises as to whether it is possible, with the knowledge at\npresent available, to go ahead with a practical program which will insure\nto the child of the future its right of rights, that of _being well-born_.\nWhen one considers the matter it is evident that much can be done at once.\nMost of the needs set forth in the preceding paragraph can clearly be met\nin a fair degree by instituting the procedures indicated.\n\nOne of the obvious duties in a restrictive way that confronts us right at\nthe start is the care and control of the feeble-minded and of the\ndefective delinquent in such a way as to prevent procreation. Much help\ncan be given also through intelligent agitation for the establishment of\ncolonies for epileptics and the higher grades of feeble-minded which can\nbe made in considerable measure self-supporting. A given colony must, of\ncourse, be for one sex alone. Much can be done, furthermore, by putting\ninto operation, both in and out of institutions, effective systems of\nregistering births and deaths together with accompanying facts which may\nprove of eugenical significance.\n\nAgain, we should more surely identify and exclude undesirable immigrants\nand also undertake thoroughgoing investigations to determine which races\nwe can not profitably assimilate into our own blood.\n\nPhysicians should pay more attention to the hereditary and congenital\naspects of their cases and make it more a matter of conscience than they\ndo at present to advise patients with regard to marriage. Prenuptial\nmedical inspection should become the custom, if not by law at least as a\nvoluntary procedure. Every parent must come to realize the grave risk to\nwhich he is subjecting his daughter if a guarantee of physical fitness,\neven more than assurance of financial standing or social position, is not\nforthcoming from her prospective mate.\n\nWholly apart from the field of heredity though in a realm intimately\nconcerned with the birthright of the child, much practical good can be\naccomplished by pondering the facts and the fictions of prenatal influence\nand in the light of the knowledge thus gained, seeing that while foolish\nand unnecessary worries are abolished, the conditions of health, nutrition\nand occupation surrounding the expectant mother are the best obtainable.\nIt is the sacred duty of every individual, moreover, to see that the\nmaximal possibilities of his own germ-plasm are not lowered by vicious or\nunwholesome living.\n\nAs individuals we can cultivate a greater sense of responsibility\nregarding marriage and parenthood in those for whose training we are\nresponsible. We can study this whole subject conscientiously, keep pace\nwith new knowledge and see that other people are likewise informed. In\nshowing an enlightened interest in the ideals of eugenics and a\nsympathetic approval of wholesome marriages, a sentiment toward parenthood\nwill gradually arise which will make it seem more desirable to many worthy\npeople than it does at present. If we are of good stock ourselves we\nshould recognize that it is highly desirable that we give to the race at\nleast four children. On the other hand, if we come from a strain which is\neugenically undesirable we should with equal conscientiousness refrain\nfrom contributing to human misery. For where serious obstacles to a union\nexist, renunciation is certainly a higher manifestation of love than is\nconsummation of a marriage which will result in untold misery to the\nobject of the affections. As a matter of fact, with adequate preliminary\nknowledge as to what actually constitutes a serious drawback to marriage,\nwhere such really exists and is recognized by the associated individuals,\nlove of the kind that leads to marriage is not likely to arise.\n\nAs has been suggested by various students of eugenics, it is even at\npresent perhaps not infeasible for earnest individuals to start in a quiet\nway local centers for the keeping and filing of accurate records of their\nfamily traits for the future use of their descendants. Such groups,\nvoluntary though they be, would soon acquire a degree of distinction that\nwould make other people of good endowments wish to join in and go on\nrecord as eugenically desirable.\n\nLastly, it should not be forgotten that good traits are inherited as\ncertainly as bad ones. Moreover, in the realm of human conduct, even\nthough the fundamental features of behavior are based on an inherited\norganization, man is not always driven by an inexorable linkage of\ninherited neutral units into only one line of conduct, since more or less\ncapacity for alternative action is also inherited. It is the personal\nduty of every member of society to aid in affording the opportunity and\nproviding the proper stimuli to insure that out of the many possibilities\nof behavior which exist in the young at birth, those forms are realized\nwhich are best worth while to the individual and to society. And while we\nrecognize that improved environment alone can not correct human\ndeficiencies we must nevertheless not relax our efforts to get cleaner\nfoods, cleaner surroundings, cleaner politics and cleaner hearts.\n\nWhy go on alleviating various kinds of misery that might equally well be\nprevented? When one squarely faces the issue, surely the absurdity of our\npresent practises can not but be evident to even the most thoughtless.\n\n=Which Shall It Be?--=As a matter of social evolution, human homes\noriginated in the necessity of an abiding place for the nurture and\ntraining of the young past their first period of helplessness. Well in the\nforeground of the mental picture which arises when we hear the very word\n_home_, are children. What shall the home of the future be with regard to\nits most important assets, the children? Shall we as a people continue to\nbe confronted at every turn by the dull countenance of the imbecile, the\ninevitable product of a bad parental mating; or the feeble body and the\nclouded intellect of the child sprung from a parentage of polluted blood;\nor the furtive cunning of the born criminal, the will-less mind of the\nbred degenerate, or the shiftless spawn of the pauper? Or shall it be a\ntype with laughing face, with bounding muscles, with unclouded brain,\noverflowing with health and happiness--in short, _the well-born child_?\n\nThe answer is in our own hands. The fate of many future generations is\nours to determine and we are false to our trusteeship if we evade the\nresponsibility clearly laid before us. How conscientiously we heed known\nfacts, how actively we acquaint ourselves with new facts, and how\neffectively we execute the obvious duties demanded by these facts, will\ngive us the answer.\n\n\nTHE END\n\n\n\n\nGLOSSARY\n\n\nACQUIRED CHARACTERS, traits developed in the body through changes in\nenvironment or function, in contra-distinction to those which have their\nspecific causes in the germ-cells.\n\nADAPTATION (L. _ad_, to; _aptus_, fit), fitness to environment.\n\nALBINISM (L. _albus_, white), a condition of deficiency in pigment.\n\nALLELOMORPH (Gr. _allelon_, of one another; _morphe_, form), one of a pair\nof alternate Mendelian characters.\n\nAMEBA (Gr. _amoibe_, change), a primitive single-celled animal.\n\nAMPHIBIAN (Gr. _amphi_, both; _bios_, life), capable of living both on\nland and in water.\n\nANTHROPOID (Gr. _anthropos_, man; _eidos_, form), man-like.\n\nARISTOGENIC (Gr. _aristos_, best; _genesis_, origin), pertaining to the\ngenetically most desirable human strains.\n\nASSOCIATION AREAS, those regions of the brain in which presumably the\nhigher mental processes are effected.\n\nATAVISM (L. _ad_, before; _avus_, grandfather), a return in one or more\ncharacters to an ancestral type. See p. 8 for restricted modern usage.\n\nATROPHY (Gr. _a_, negative; _trophe_, nourishment), a wasting away of a\npart of a living organism.\n\nAXON (Gr. _axon_, axis), the process from a nerve cell which becomes a\nnerve fiber.\n\nBINET-SIMON SCALE, a series of tests graded to age and previous training\nof the average normal child, much used in measuring mental deficiency.\n\nBIOLOGY (Gr. _bios_, life; _logos_, discourse), the study of life and of\nliving things.\n\nBIOMETRY (Gr. _bios_, life; _metron_, measure), the study of biological\nproblems by means of statistical methods.\n\nBLASTOMERE (Gr. _blastos_, germ; _meros_, part), one of the early cells\nformed by the division of the ovum.\n\nBLASTOPHTHORIA (Gr. _blastos_, germ; _phtheiro_, destroy), deterioration\nof the germ as the result of direct pathogenic or other disturbing agents.\n\nBLENDING INHERITANCE, inheritance in which the characters of the parents\nseem to blend in the offspring.\n\nCACOGENIC (Gr. _kakos_, bad; _genesis_, origin), pertaining to genetically\nundesirable human strains.\n\nCELL, the fundamental unit of structure in plants and animals.\n\nCENTROSOME (Gr. _kentron_, center; _soma_, body), a small body which\nfunctions in indirect cell-division.\n\nCHARACTER, any distinguishing feature, trait or property of an organism.\n\nCHEMOTROPISM (chemical and tropism), defined, p. 198.\n\nCHROMATIN (Gr. _chroma_, color), deeply staining substance of the\ncell-nucleus.\n\nCHROMOSOMES (Gr. _chroma_, color; _soma_, body), characteristic deeply\nstaining bodies, typically constant in number and appearance in each\nspecies of animal or plant, which appear in the cell during indirect\ndivision.\n\nCHROMOTROPISM (Gr. _chroma_, color; _trope_, turning), defined, p. 198.\n\nCLEAVAGE, the division of the egg-cell into many cells.\n\nCONGENITAL (L. _con_, together; _gigno_, bear), present at birth.\n\nCONJUGATION (L. _con_, together; _jugum_, yolk), the union of germ-cells\nor unicellular individuals for reproduction.\n\nCONSTRUCTIVE (or positive) EUGENICS, a system of securing a superior race\nthrough propagation of the fittest individuals.\n\nCORTEX (L. _cortex_, bark), the outer or investing layer of the brain.\n\nCYTOPLASM (Gr. _kytos_, cell; _plasso_, form), the protoplasm of the cell\noutside of the nucleus.\n\nDALTONISM, the commonest form of color-blindness in which the affected\nindividual is unable to discriminate between red and green.\n\nDENDRITES (Gr. _dendron_, tree), branching processes which spring from\nnerve-cells.\n\nDETERMINER (L. _determinare_, to determine), the distinctive cause or unit\nin a germ-cell which determines the development of a particular character\nin the individual derived from that cell. The terms _gene_ and _factor_\nare sometimes used as synonyms of determiner.\n\nDIHYBRIDS (L. _di_, two; _hybrida_, mongrel), the offspring of parents\ndiffering in two characters.\n\nDIPLOID (Gr. _diploos_, double; _eidos_, form), the dual or somatic number\nof chromosomes.\n\nDOMINANT CHARACTER (L. _dominare_, to be a master), a character from one\nparent which manifests itself in offspring to the exclusion of a\ncontrasted character from the other parent.\n\nDROSOPHILA, a genus of fruit-flies of which there are several species.\n\nDUPLEX (L. _duo_, two; _plico_, fold), the condition in which a character\nis represented by two determiners, one from each parent.\n\nELECTROTROPISM (Gr. _electron_, amber; _trope_, turning), defined, p. 198.\n\nEMBRYO (Gr. _embryon_), the young organism in its earliest stages of\ndevelopment.\n\nEMBRYOGENY (Gr. _embryon_; _genesis_, generation), the development of the\nembryo.\n\nEUGENICS (Gr. _eugenes_, well-born), the science relating to improvement\nof the human race through good breeding.\n\nFACTOR, the determiner of a particular hereditary character.\n\nFEEBLE-MINDEDNESS, deficiency in mental development. For grades, see p.\n244.\n\nFERTILIZATION, union of the sexual cells.\n\nFETUS (L. _feuere_, to bring forth), the unborn young animal in its later\n(after the second month in man) stages of development.\n\nFLAGELLUM (L. _flagellum_, little whip), a vibratile, thread-like organ of\nlocomotion.\n\nGAMETE (Gr. _gamos_, marriage), a mature germ-cell.\n\nGENETICS (Gr. _genesis_, origin), the science which deals with heredity\nand the origin of individuals in general.\n\nGENOTYPE (Gr. _genea_, race; _typto_, strike), the germinal constitution\nof an organism.\n\nGEOTROPISM (Gr. _ge_, earth; _trope_, turning), defined, p. 198.\n\nGERM-CELL, a reproductive cell.\n\nGERMINAL VARIATIONS, variations which owe their origin to some\nmodification in the germ-cells.\n\nGERM-PLASM, the material basis of inheritance.\n\nGONAD (Gr. _gonos_, generation), a germ-gland.\n\nHAPLOID (Gr. _haploos_, single; _eidos_, form), the single or reduced\nnumber of chromosomes as found, for instance, in the mature germ-cells.\n\nHELIOTROPISM (Gr. _helios_, sun; _trope_, turning), defined, p. 198.\n\nHEREDITY (L. _heres_, heir), resemblance of individuals to their\nprogenitors based on community of origin.\n\nHERITAGE (L. _heres_, heir), all that is inherited by an individual.\n\nHETEROZYGOTE (Gr. _heteros_, other; _zygon_, yolk), an individual produced\nthrough the union of germ-cells which are unlike in one or more\ndeterminers. Adjective, _heterozygous_.\n\nHOMOZYGOTE (Gr. _homos_, same; _zygon_, yolk), an individual produced\nthrough the union of germ-cells which are alike in determiners. Adjective,\n_homozygous_.\n\nHYBRID (L. _hybrida_, mongrel), the offspring of parents which differ in\none or more characters.\n\nIDENTICAL TWINS, twins which show identical inborn characters, both having\ncome presumably from the same ovum.\n\nIDIOT (Gr. _idios_, peculiar, private), defined, p. 244.\n\nIMBECILE (L. _imbecillis_, weak), defined, p. 244.\n\nINHERITANCE (L. _in_, in; _heres_, heir), the sum of all characters which\nare transmitted by the germ-cells from generation to generation.\n\nINHIBITOR (L. _in_, in; _habeo_, hold, have), that which checks or\nrestrains.\n\nINSTINCT (L. _in_, in; _stingno_, prick), defined, p. 203.\n\nINTRA-UTERINE (L. _intra_, within; _uterus_, the womb), within the womb.\n\nIRRITABILITY (L. _irrito_, excite), the property of responding to stimuli.\n\nLININ (L. _linum_, flax), filaments of the cell-nucleus not readily\nstained by dyes.\n\nLUETIN TEST (L. _lues_, pest), a test for syphilis; see p. 188.\n\nMAMMALS (L. _mamma_, breast), warm-blooded, hairy animals which suckle\ntheir young.\n\nMATURATION (L. _maturus_, ripe), the final stages in the development of\nthe sex-cells characterized by two divisions in one of which the number of\nchromosomes is reduced by one-half.\n\nMENDELIAN, MENDELISM, referring to Mendel, the founder of a theory of\nheredity. See p. 67.\n\nMETAZOA (Gr. _meta_, over; _zoon_, animal), all animals higher than the\nprotozoa.\n\nMITOSIS (Gr. _mitos_, thread), indirect nuclear division, characterized by\nthe appearance of a fibrous spindle and a definite number of chromosomes.\nThe latter split to form daughter chromosomes which diverge to the poles\nof the spindle to form parts of the new nuclei.\n\nMONGOLIAN, a type of feeble-minded individual, see p. 248.\n\nMONOHYBRID (Gr. _monos_, single; L. _hybrida_, mongrel), the offspring of\nparents, differing in one character.\n\nMORON (Gr. _moros_, foolish), defined, p. 244.\n\nMUTATIONS (L. _mutare_, to change), abrupt, inheritable germinal\nvariations. Frequently though not necessarily they are changes of\nconsiderable extent.\n\nNEURAL (Gr. _neuron_, nerve), pertaining to the nervous system.\n\nNEURON (Gr. _neuron_, nerve), a nerve-unit consisting of a nerve-cell with\nbranching processes called dendrites and an axon or axis cylinder process\nwhich gives rise to a nerve fiber.\n\nNEUROPATHIC (Gr. _neuron_, nerve; _pathos_, suffering), relating to\ndisease of the nervous system.\n\nNUCLEOLUS (L. dim. of nucleus), a well-defined body found within the\nnucleus of a cell.\n\nNUCLEUS (L. _nux_, a nut), the central organ of a cell.\n\nNULLIPLEX (L. _nullus_, not any; _plico_, fold), the condition in which no\ndeterminers of a given character exist in a particular individual.\n\nOOeCYTE (Gr. _oon_, egg; _kytos_, cell), the ovarian egg in one stage of\ndevelopment.\n\nOOeGENESIS (Gr. _oon_, egg; _genesis_, origin), the development of ova from\nprimitive sex-cells.\n\nOOeGONIUM (Gr. _oon_, egg; _gonos_, generation), a primordial egg-cell.\n\nOVARY (L. _ovum_, egg), the organ in which the egg-cells multiply and are\nnourished.\n\nOVUM (L. _ovum_, an egg), the female sex cell.\n\nPARTHENOGENESIS (Gr. _parthenos_, virgin; _genesis_, origin), development\nof an egg which has not united with a male gamete.\n\nPHENOTYPE (Gr. _phaino_, show; _typto_, strike), the existing type of\nindividual irrespective of hereditary possibilities which may reside in it\nundeveloped.\n\nPHOTOTROPISM (Gr. _phos_, light; _trope_, turning), defined, p. 198.\n\nPLACENTA (L. _placenta_, a flat cake), the organ by which the fetus of the\nhigher mammals is attached to the uterine wall of the mother for purposes\nof nourishment, respiration and excretion. In it the maternal and fetal\nblood, although not intermingling, are brought into such close proximity\nthat an interchange of dissolved substances is possible.\n\nPOLAR BODIES, the minute cells which are separated from the egg in its\nmaturation divisions.\n\nPRIMATE (L. _primus_, first), the highest order of animals, including\nmonkeys, apes and man.\n\nPRONUCLEUS, the nucleus of the mature ovum or sperm-cell.\n\nPROTOPLASM (Gr. _protos_, first; _plasma_, form), the essential living\nsubstance.\n\nPROTOZOA (Gr. _protos_, first; _zoon_, animal), single-celled animals or\nanimals composed of cells not separable into different tissues.\n\nPSYCHICAL (Gr. _psyche_, the soul), pertaining to the mind.\n\nRECESSIVE CHARACTER (L. _recessus_, a going back), a character from one\nparent which remains undeveloped in offspring when associated with the\ncorresponding dominant character from the other parent.\n\nREDUCTION DIVISION, a division of the maturing germ-cells in which the\ndual or somatic (diploid) number of chromosomes is reduced to the single\n(haploid) number.\n\nREFLEX ACTION (L. _re_, back; _flectere_, bend), an automatic response of\nthe nervous and motor mechanism of the body.\n\nRESTRICTIVE (or negative) EUGENICS, a system of improving the human race\nby preventing reproduction of the unfit.\n\nREVERSION (L. _re_, back; _verto_, turn), the reappearance of ancestral\ntraits which have for some generations been in abeyance.\n\nRHEOTROPISM (Gr. _rheo_, to flow; _trope_, turning), defined, p. 198.\n\nSALPINGECTOMY (Gr. _salpinx_, trumpet; _ectome_, cutting out), removal of\npart or all of a Fallopian tube (oviduct).\n\nSEGREGATION (L. _se_, aside; _grex_, flock), separation.\n\nSEX CHROMOSOME, a special chromosome which is supposed to be concerned in\nthe determination of sex.\n\nSEX-LINKED CHARACTERS, defined, p. 60.\n\nSIMIAN (L. _simia_, ape), ape-like.\n\nSIMPLEX (L. _sim_, same; _plico_, fold), the condition in which a\ncharacter is represented by a determiner from only one of the two parents.\n\nSOMA (Gr. _soma_, body), the body considered apart from the germ-cells.\n\nSPERMATID (Gr. _sperma_, seed), a cell resulting from the last division of\nthe germ-cell in spermatogenesis. It transforms into the spermatozoon.\n\nSPERMATOCYTES (Gr. _sperma_, seed; _kytos_, cell), cells concerned in the\nmaturation divisions of the male germ-cells.\n\nSPERMATOGENESIS (Gr. _sperma_, seed; _genesis_, origin), the development\nof spermatozoa from primitive sex-cells.\n\nSPERMATOGONIUM (Gr. _sperma_, seed; _gonos_, generation), a primordial\nsperm-cell.\n\nSPERMATOZOON (Gr. _sperma_, seed; _zoon_, animal), the functional male\nsex-cell.\n\nSPINDLE, a fibrous organ formed in indirect cell-division.\n\nSPIREME (L. _spira_, coil), a characteristic stage preliminary to indirect\ncell-division in which the chromatin material of the nucleus appears in\nthe form of a skein of filaments.\n\nSTEREOTROPISM (Gr. _stereos_, solid; _trope_, turning), defined, p. 198.\n\nSTERILIZATION (L. _sterilis_, barren), deprivation of reproductive power.\nFor methods, see p. 322.\n\nSYNAPSE (Gr. _syn_, together; _hapto_, unite), the coming in contact of\nthe processes of one nerve cell with the processes or body of another.\n\nSYNAPSIS (Gr. _syn_, together; _hapto_, unite), union of the chromosomes\nin pairs preliminary to the reduction division.\n\nTELEGONY (Gr. _telegonos_, born far away), the supposed influence of an\nearlier sire on offspring born later of the same mother to a different\nsire.\n\nTHERMOTROPISM (Gr. _thero_, heat; _trope_, turning), defined, p. 198.\n\nTHIGMOTROPISM (Gr. _thigmo_, touch; _trope_, turning), defined, p. 198.\n\nTOXIN (Gr. _toxicon_, poison), poisonous compounds of animal, vegetable,\nor bacterial origin.\n\nTROPISM (Gr. _trope_, turning), the automatic directing of an organism\ntoward or away from a source of stimulus.\n\nUNIT-CHARACTER, a character which behaves as an indivisible unit in\nheredity.\n\nVASECTOMY (L. _vas_, vessel; _ektome_, cutting out), removal of a portion\nof the vas deferens (duct for conveying spermatozoa).\n\nVESTIGEAL (L. _vestigium_, footstep), representing organs which existed\nonce in a more developed condition.\n\nVOLVOX (L. _volvo_, roll), a small fresh-water organism occurring in\nspherical colonies.\n\nWASSERMAN REACTION, a test for syphilis, see p. 188.\n\nX-ELEMENT, same as sex-chromosome.\n\nZYGOTE (Gr. _zygon_, yolk), the product of the union of two gametes.\n\n\n\n\nREFERENCES FOR FURTHER READING AND STUDY\n\n\nBATESON, W., 1909. _Mendel's Principles of Heredity._ Cambridge, The\nUniversity Press. The best technical account of Mendelism. It contains\nalso a translation of the original papers of Mendel.\n\nCASTLE, WILLIAM E., 1911. _Heredity._ New York, D. Appleton and Company.\n\nCASTLE, WILLIAM E.; COULTER, JOHN M.; DAVENPORT, CHARLES B.; EAST, EDWARD\nM.; TOWER, WILLIAM L., 1912. _Heredity and Eugenics._ Chicago, The\nUniversity of Chicago Press.\n\nCONKLIN, EDWIN GRANT, 1915. _Heredity and Environment in the Development\nof Men._ Princeton, Princeton University Press.\n\nDAVENPORT, CHARLES B., 1911. _Heredity in Relation to Eugenics._ New York,\nHenry Holt and Company.\n\nDONCASTER, L., 1911. _Heredity in the Light of Recent Research._\nCambridge, The University Press.\n\nDONCASTER, L., 1915. _The Determination of Sex._ Cambridge, The University\nPress.\n\nELLIS, HAVELOCK, 1912. _The Task of Social Hygiene._ New York, Houghton\nMifflin Company.\n\nGALTON, FRANCIS, 1869. _Hereditary Genius: an Inquiry Into Its Laws and\nConsequences._ London, Macmillan and Company.\n\nGALTON, FRANCIS, 1889. _Natural Inheritance._ New York, The Macmillan\nCompany.\n\nGALTON, FRANCIS, 1895. _English Men of Science; Their Nature and Nurture._\nNew York, D. Appleton and Company.\n\nGALTON, FRANCIS, and SCHUSTER, EDGAR, 1906. _Noteworthy Families_ (Modern\nScience). London, J. Murray.\n\nGODDARD, HENRY HERBERT, 1912. _The Kallikak Family; a Study in the\nHeredity of Feeble-mindedness._ New York, The Macmillan Company.\n\nGODDARD, HENRY HERBERT, 1914. _Feeble-mindedness; Its Causes and\nConsequences._ New York, The Macmillan Company.\n\nHEALY, WILLIAM, 1915. _The Individual Delinquent._ Boston, Little, Brown\nand Company.\n\nKELLICOTT, WILLIAM E., 1911. _The Social Direction of Human Evolution; an\nOutline of the Science of Eugenics._ New York, D. Appleton and Company.\n\nMORGAN, THOMAS HUNT, 1913. _Heredity and Sex._ New York, Columbia\nUniversity Press.\n\nPUNNETT, R. C., 1911. _Mendelism._ New York, The Macmillan Company. The\nbest popular account of Mendelism.\n\nSALEEBY, CALEB WILLIAM, 1909. _Parenthood and Race Culture; an Outline of\nEugenics._ London, Cassell and Company.\n\nSCHUSTER, EDGAR, 1912. _Eugenics._ London, Collins Clear-Type Press.\n\nTHOMSON, J. ARTHUR, 1908. _Heredity._ London, John Murray.\n\nWALTER, HERBERT EUGENE, 1913. _Genetics._ New York, The Macmillan Company.\n\nWHETHAM, W. C. D. and C. D., 1909. _The Family and the Nation._ London,\nLongmans, Green and Company.\n\nWOODS, FREDERICK ADAMS, 1906. _Mental and Moral Heredity in Royalty._ New\nYork, Henry Holt and Company.\n\nVARIOUS AUTHORS, 1914. _Eugenics; Twelve University Lectures._ New York,\nDodd, Mead and Company.\n\nJOURNALS:\n\n    _The Journal of Heredity._ The organ of the American Genetic\n    Association, Washington, D. C.\n\n    _The Eugenics Review._ Issued at the University of London.\n\n    _Memoirs and Bulletins_ published by the Eugenics Record Office, Cold\n    Spring Harbor, Long Island, N. Y.\n\nEvery one interested in eugenics should be acquainted with the work of\nthis office. In its own words its functions are:\n\n    1. To serve eugenical interests in the capacity of repository and\n    clearing house.\n\n    2. To build up an analytical index of the traits of American families.\n\n    3. To train field workers to gather data of eugenical import.\n\n    4. To maintain a field force actually engaged in gathering such data.\n\n    5. To cooperate with other institutions and with persons concerned\n    with eugenical study.\n\n    6. To investigate the manner of inheritance of specific human traits.\n\n    7. To advise concerning the eugenical fitness of proposed marriages.\n\n    8. To publish results of researches.\n\n    To such persons as will undertake to fill them out it furnishes free\n    in duplicate (one copy to be retained by the applicant) the following\n    blank schedules: 1. _Record of Family Traits._ 2. _Index to\n    Germ-plasm--A Parallel Family Record for Prospective Marriage Mates._\n    3. _Musical Talent._ 4. _Mathematical Talent._ 5. _Tuberculosis._ 6.\n    _Special Trait Chart._ 7. _Harelip and Cleft-palate._\n\n    _Publications of the Volta Bureau_ of Washington, D. C., an\n    institution given over entirely to data regarding deaf mutes.\n\n    _Studies in National Deterioration._ The University of London.\n\n    _Memoirs and Lectures_, from the Biometric Laboratory, University of\n    London.\n\n    _Treasury of Human Inheritance_, a series of studies being issued from\n    the Eugenics Laboratory, University College, London.\n\n\n\n\nINDEX\n\n\n  Ability: 118;\n    calculating, literary, musical, 120.\n\n  Able child likely to be neglected, 257.\n\n  Achondroplasy, 113.\n\n  Acquired characters, inheritance of, 121.\n\n  Adami, 164.\n\n  Adaptations, establishment of, 140.\n\n  Adaptive responses, 201.\n\n  Agassiz, 297.\n\n  Albinism, in man, 116.\n\n  Alcohol: and crime, 279;\n    and degeneracy, 172, 179;\n    and germinal tissue, 172;\n    a poison, 168.\n\n  Alcoholism: 101, 117, 167;\n    factors in, 180;\n    in lower animals, 173-178;\n    views regarding inheritance of, 169, 170, 172, 178, 179, 180.\n\n  Alkaptonuria, 117.\n\n  Allelomorph, 77.\n\n  Alpine plants, non-inheritance of acquired characters, 131.\n\n  Alternative action in behavior, 207.\n\n  Altruism, possible origin of, 220.\n\n  Ambystoma, 132.\n\n  Ameba, 23, 24.\n\n  Ancestors, number of, 4.\n\n  Ancestry: a network, 3;\n    dual, 6;\n    in royalty, 5;\n    pride of, as a eugenic agent, 309.\n\n\n  Backward child, 256.\n\n  Backwardness, importance of early determination, 256, 257.\n\n  Bardeen, 126.\n\n  Barker, 229.\n\n  Barr, 246, 247, 248.\n\n  Barrington, 179.\n\n  Bateson, 77, 82.\n\n  Bees, inheritance in, 136, 137.\n\n  Behavior: lower animals, 197;\n    modifiability of, 200, 204-207, 217, 219, 224, 225, 337;\n    not wholly established by heredity, 217, 227;\n    rational, 205, 206;\n    various forms of, possible, 207, 219.\n\n  Bell, 152.\n\n  Bezzola, 170.\n\n  Billings, 249.\n\n  Binet-Simon test, 255.\n\n  Biometry, 16.\n\n  Birthmarks, 159, 160.\n\n  Birth-rate: significance of, 302;\n    too low in desirable stocks, 302, 304, 305, 307.\n\n  Blastomeres, 55.\n\n  Blastophthoria, 163.\n\n  Blended inheritance, 87, 92, 93.\n\n  Blends, mistakes for, 91.\n\n  Blindness, infantile, 183.\n\n  Blistering, 113.\n\n  Body: how built up from germ, 36;\n    duality of, 50.\n\n  Brachydactylism, 107.\n\n  Brain: in higher animals, 213;\n    mechanism, maladjustments of, 230.\n\n  Branthwaite, 180, 292.\n\n  Breeding, experiments, method of, 14, 15.\n\n  Brewer, 142.\n\n  Brieux, 101.\n\n  Bronner, 266.\n\n  Brown Sequard, 132, 133.\n\n\n  Cabot, 183.\n\n  Cacogenic strains, 310.\n\n  Cajal, 209.\n\n  Cancer, 117, 154.\n\n  Capsella, 131.\n\n  Castle, 134.\n\n  Cataract, presenile, 112.\n\n  Cattle: horn characters, 79;\n    roan, 81.\n\n  Cell: a unit of structure, 20;\n    diagram of, 21;\n    structure of, 20, 30.\n\n  Cell-division: 31;\n    indirect (mitosis), 32;\n    meaning of indirect, 34.\n\n  Cell-theory, 22.\n\n  Cellular basis of heredity, 22.\n\n  Ceni, 174.\n\n  Centrosome, 31.\n\n  Cerebral cortex, not functionally homogeneous, 211.\n\n  Character: defined, 12;\n    dominant, 74;\n    recessive, 74.\n\n  Characters: contrasted, 69;\n    determiners of, 13, 14;\n    independence of, 69;\n    inheritable and non-inheritable, 121, 122;\n    more than two pairs of, 87;\n    new combinations of, 82, 83, 84;\n    separable, 69;\n    symbols for, 78;\n    two pairs of, 82.\n\n  Chauvin, 132.\n\n  Chemotropism, 198.\n\n  Childbirths, intervals between, 165.\n\n  Children of the future: ours to determine quality of, 338, 339;\n    and home, 338.\n\n  Cholera, 152.\n\n  Chorea: 117;\n    Huntington's, 113-115, 243, 325.\n\n  Chromatin, 31.\n\n  Chromosome, 32.\n\n  Chromosomes: individuality of, 39, 48;\n    determiners in, 94;\n    in germ and body cells, 40;\n    Mendelian factors and, 93;\n    number and appearance, 34, 41;\n    pairs of, 40, 93, 94;\n    significance of, in heredity, 35, 49, 50, 51, 53, 54.\n\n  Chromotropism, 198.\n\n  Church, 242.\n\n  Cleavage, 36.\n\n  Cleft-palate, 178.\n\n  Cole, 166.\n\n  College graduates and birth-rate, 304.\n\n  Coloboma, 113.\n\n  Color-blindness, 60-62.\n\n  Conceptual thought, origin of, 206.\n\n  Conduct: importance to young of practise, 221, 223;\n    hereditary predisposition and, 218, 337;\n    responsibility for, 195.\n\n  Congenital traits, 123.\n\n  Conjugation, 25.\n\n  Consciousness, 206.\n\n  Conservation: of superior strains, 157;\n    human, 299, 300.\n\n  Constructive eugenics, 309.\n\n  Corneal opacity, 113.\n\n  Correns, 68.\n\n  Cortex of brain, 195, 213.\n\n  Cost, of caring for our disordered and delinquent, 257, 300.\n\n  Cretins, effects of segregating the sexes, 321.\n\n  Crime: and delinquency, 263, 287;\n    and feeble-mindedness, 264-270;\n    bearings of immigration on, 280;\n    classifications of, 276;\n    defined, 276;\n    heredity vs. environment in, 263;\n    increase in, 272;\n    mental disorders most frequently associated with, 279;\n    no specific hereditary factor for, 275.\n\n  Criminal: the born, 277;\n    the epileptic, 277.\n\n  Criminality, 117.\n\n  Criss-cross inheritance, 61.\n\n  Criteria for judging reproductive fitness, 304, 306.\n\n  Cytoplasm: 30;\n    in heredity, 51.\n\n\n  Daltonism, 60.\n\n  Dana, 257.\n\n  Darwin, pedigree of, 316.\n\n  Davenport, 92, 116, 231, 243, 257, 271, 273, 284, 291, 304, 312.\n\n  Davis, 185.\n\n  Deaf-mutism, 152, 153.\n\n  Death, natural, 28.\n\n  Decline of nations, 290, 300.\n\n  Defective delinquent, should prevent procreation of, 335.\n\n  Defectives: increase due to breeding, 290, 291;\n    natural elimination done away with among, 292;\n    unpardonable to let multiply, 288.\n\n  Defects: breeding out, 118, 119;\n    mental and nervous, 228.\n\n  Degenerate strains: 269;\n    not a product of surroundings, 273.\n\n  Degenerates, sterilization of married, 330.\n\n  Delinquency, causes of, 267, 274.\n\n  Delinquents not all defectives, 274.\n\n  Delinquent women and girls, many mentally defective, 265, 266.\n\n  Dendrite, 208.\n\n  De Sanctis, 256.\n\n  Determiners: 13, 77;\n    different producing the same character, 88, 90;\n    segregation of, 84.\n\n  Development: in higher organisms, 28;\n    suppressed, 9.\n\n  De Vries, 68.\n\n  Diabetes, 113.\n\n  Difficulty, educational value of, 222, 223.\n\n  Digital malformations, 107.\n\n  Dihybrids, 82.\n\n  Diploid number of chromosomes, 41, 43.\n\n  Disease: defined, 146;\n    inheritance of, 98, 148;\n    predisposition to, 148;\n    reappearance of not necessarily inheritance, 146.\n\n  Dominance: 74;\n    delayed, 81;\n    incomplete, 80, 100;\n    in human genealogies, 102;\n    in man, 99, 107.\n\n  Don Carlos, number of ancestors, 5.\n\n  Drosophila, 66.\n\n  Duplex character, 80, 99.\n\n  Dwarfing, by starvation, 130.\n\n  Dwarfs, true, 117.\n\n\n  East, 91.\n\n  Education: actual practise in carrying out projects important, 221;\n    affording opportunity for development of good traits, 226;\n    effects of not inherited, 142, 155;\n    establishing pathways through the nervous system, 210;\n    importance of difficulty in, 222, 223;\n    non-transference of skill acquired in one line to other lines, 213;\n    providing proper stimuli, 226;\n    training in motive necessary, 220;\n    value of interest in, 223.\n\n  Egg, a cell, 22.\n\n  Egg-cell and sperm-cell contrasted, 29.\n\n  Elderton, 179, 296.\n\n  Electrotropism, 198.\n\n  Ellis, 265, 301.\n\n  Embryo, relation to mother, 161.\n\n  Embryogeny, 36.\n\n  Emerick, 251.\n\n  Environment: direct action on germ cells, 124, 125;\n    effects of faulty, 158;\n    in crime and delinquency, 263, 266, 273, 274.\n\n  Epidermolysis, 113.\n\n  Epilepsy: 101, 117, 242, 249, 251, 252, 253;\n    in guinea-pigs, 132;\n    relation to feeble-mindedness, 249.\n\n  Epileptic, the criminal type, 277-279.\n\n  Epileptics, number of, 230, 246, 250.\n\n  Eugenic agent, educated public sentiment, 330.\n\n  Eugenics: and education, 309;\n    and personal liberty, 332;\n    a working program of, 335;\n    constructive, based on education, 301;\n    defined, 293;\n    desirable traits, 306;\n    education of women in, 333;\n    influence of public opinion on, 331;\n    much yet to be done, 333, 334;\n    positive and negative, 301.\n\n  Ewart, 10, 165.\n\n  Exceptional child likely to be neglected, 257.\n\n  Experimental breeding, method of, 15.\n\n  External conditions, influences of, 130.\n\n  Eye-color: 9, 103;\n    inheritance of, 104.\n\n  Eye-defects, 108, 110.\n\n\n  Family pride and eugenics, 309.\n\n  Farabee, 106.\n\n  Fay, 153.\n\n  Feeble-minded: prevention of procreation in, 258, 335;\n    results of non-restraint, 246.\n\n  Feeble-mindedness: 101, 117;\n    and crime, 264-269, 279;\n    grades of, 244;\n    inheritance of, 245;\n    not insanity, 238;\n    relation of alcohol to, 169-172.\n\n  Fernald, 256, 266.\n\n  Fertilization, 26, 29, 47, 48.\n\n  Fetus: poisoning of, 162;\n    relation to mother, 161.\n\n  Fiber-tracts in man, 214.\n\n  Fitness, criteria for judging, 304, 306.\n\n  Flexner, 186.\n\n  Forel, 169, 173, 303.\n\n  Fowl, Andalusian, 69, 70, 71.\n\n  Frederick the Great, number of ancestors, 5.\n\n  Friedreich's disease, 117.\n\n  Fruit-fly, 66.\n\n\n  Galton, 293, 295.\n\n  Gamete, 28, 40.\n\n  Gametes in dihybrids, 85.\n\n  Gametic matings in man, 100.\n\n  Geddes, 55.\n\n  Genealogies, imperfect, 98.\n\n  Genotype, 86.\n\n  Geotropism, 198.\n\n  Germ and body distinct, 37, 38.\n\n  Germ: control of possibilities in, 224;\n    singleness of, 50.\n\n  German emperor, number of ancestors, 5.\n\n  Germ-cells: affected by poisons, 126;\n    changes in, 126, 127;\n    early set apart, 37;\n    question of effects of body on, 128, 135;\n    effects of external influences on, 124;\n    in Miastor, 37, 38;\n    metabolic changes in, 138;\n    origin of, 36, 37;\n    possibilities of development, 127;\n    two classes of, 71, 73.\n\n  Germinal continuity, 39.\n\n  Germinal variation and the origin of new characters: 138;\n    cases analyzed, 141;\n    sexual reproduction in relation to, 138.\n\n  Germ-plasm and bad environment, 194.\n\n  Gifted persons, 212.\n\n  Glaucoma, 113.\n\n  Goddard, 118, 171, 174, 188, 235, 238, 245, 250, 256, 257, 264, 269, 326.\n\n  Gonads, transplantation of, 134.\n\n  Gonorrhoea: seriousness of, 182;\n    prevalence, 183.\n\n  Gorst, 234.\n\n  Gout, 153, 234.\n\n  Guinea-pigs: alcoholism in, 175;\n    Mendelism in, 75.\n\n  Guyer, 59.\n\n\n  Habit, 219.\n\n  Habits, modification of in lower animals, 204.\n\n  Hair-color, 105.\n\n  Hair shape, 105.\n\n  Hamburger, 150.\n\n  Handwriting, 120.\n\n  Haploid number of chromosomes, 41, 43.\n\n  Harelip, 178.\n\n  Hart, 266, 319, 326.\n\n  Healy, 256, 274, 278.\n\n  Hearing, hardness of, 118.\n\n  Heart disease, 154.\n\n  Hegner, 27, 38.\n\n  Heliotropism, 198.\n\n  Helm, 109, 111.\n\n  Hemophilia, 64.\n\n  Hereditary character defined, 12.\n\n  Hereditary mingling, mosaic rather than blend, 13.\n\n  Hereditary transmission, laws of, 68.\n\n  Heredity: and environment, 295;\n    dual ancestry in, 6;\n    defined, 1;\n    false, 163;\n    human, uncertainty of records, 98;\n    in protozoa, 22, 23;\n    in insanity, importance of, 261;\n    in sexually reproducing forms, 7;\n    in unicellular forms, 22, 23;\n    methods of study, 14, 15;\n    new discoveries in, 67;\n    not a blend, 13;\n    race betterment through, 289.\n\n  Heritage, blood, 1.\n\n  Heron, 307.\n\n  Heterozygote: 80;\n    detection of, 80.\n\n  Hill-folk, the, 271.\n\n  Hodge, 175.\n\n  Holmes, 203.\n\n  Home, for children, 338.\n\n  Homozygote, 80.\n\n  Huntington's chorea, 113-115, 243, 325.\n\n  Huxley, 195, 205.\n\n  Hybrids: 52;\n    whites and negroes, 297, 298.\n\n  Hypotrichosis, 113.\n\n  Hysteria, 117.\n\n\n  Ichthyosis, 65.\n\n  Ideals, importance of establishing in children, 223.\n\n  Idiots, 244.\n\n  Imbeciles, 244.\n\n  Immigrants, duty of excluding undesirable, 335.\n\n  Immigration: and mental unsoundness, 281, 282;\n    bearing on crime and delinquency, 280;\n    bearing on venereal diseases, 282;\n    importance of restricting, 283, 335.\n\n  Immortality: of protozoa, 23;\n    of the race, 3.\n\n  Immunity, artificial, not inherited, 155.\n\n  Inbreeding, in defectives, 271.\n\n  Individual, and race, 3.\n\n  Inebriate women, offspring of, 168.\n\n  Inebriety, constitutional, 180.\n\n  Infant mortality, 149.\n\n  Infection, prenatal, 147.\n\n  Inheritance: and disease, 146;\n    blended, 87, 93;\n    of tendencies, 107.\n\n  Inhibitions, 216.\n\n  Inhibitors, 79.\n\n  Insane, increase in numbers of, 233, 234.\n\n  Insanity: 117;\n    certain forms recessive, 243;\n    eugenical significance of, 234, 235, 240;\n    importance of early diagnosis, 259;\n    some forms not hereditary, 260;\n    types of, 239;\n    prevalence in the United States, 228, 229.\n\n  Insect colors, effect of temperature, 129.\n\n  Instincts: 203;\n    adjustable, 203;\n    not inherited acquirements, 144;\n    origin of intelligent behavior from, 203, 204.\n\n  Institutional figures misleading, 266.\n\n  Intelligence, 205, 206.\n\n  Intelligent behavior, opening up possibilities of, 204.\n\n  Ireland, 171.\n\n  Irritability, characteristics of living protoplasm, 197.\n\n\n  Jennings, 203, 204.\n\n  Johnson, 305.\n\n  Johnstone, 245, 319, 320, 321.\n\n  Jolly, 243.\n\n  Jordan, 4, 299.\n\n  Jukes, 270.\n\n\n  Kallikak family, 269, 270.\n\n  Kellicott, 314, 316.\n\n  Kellogg, 299.\n\n  Keratosis, 113.\n\n  Kidney diseases, 154.\n\n  Kirby, 187, 324.\n\n  Knox, 256.\n\n  Kraeplin, 242.\n\n\n  Laitinen, 174.\n\n  Language, as mental aid, 206, 207.\n\n  Lapsed intelligence, theory of, 145.\n\n  Larval stages, susceptibility of, 128.\n\n  Laws, sterilization, 323, 327, 329.\n\n  Lead-poisoning: 163;\n    experiments on rabbits, 163.\n\n  Lederbaur, 131.\n\n  Legal restraint of defectives limited, 331.\n\n  Lens: displaced, 113;\n    cataract, 112.\n\n  Leprosy, 152.\n\n  Leptinotarsa, production of variations in, 125.\n\n  Linden, Countess von, 129.\n\n  Linin, 31.\n\n  Little's disease, 215.\n\n  Locomotor ataxia, 187.\n\n  Loeb, 62, 203.\n\n  Longevity, 120.\n\n  Lord Morton's mare, 10.\n\n  Lorenz, 113, 114, 115.\n\n  Low birth-rate, 308.\n\n  Lowell, Judge John, 312.\n\n  Luetin test, 188.\n\n  Lunborg, 243.\n\n\n  MacDougal, 125.\n\n  Margaret, Mother of Criminals, 270.\n\n  Marriage: barriers to, 331;\n    inter-racial, 296;\n    medical inspection before, 191.\n\n  Mast, 203.\n\n  Maternal impressions, 159-160.\n\n  Maturation: 39, 41, 43, 44;\n    parallel between egg and sperm-cell, 44, 46.\n\n  Mechanical skill, 120.\n\n  Mechanism of heredity, 22, 25, 26, 28, 29, 30, 35, 37, 40-54, 94, 95.\n\n  Melancholia and crime, 279.\n\n  Memory: 120, 204;\n    not a complete test of normality, 268, 269.\n\n  Mendel: 68;\n    work on peas, 82.\n\n  Mendelian factors and chromosomes: 93;\n    inheritance and man, 97;\n    principles, rediscovery of, 68;\n    ratio, cause of, 71.\n\n  Mendelism, 67, 69.\n\n  Mental and nervous defects, 228.\n\n  Mental defective: defined, 255;\n    disproportionate increase in, 232;\n    numbers married, 231, 232;\n    inefficiency of marriage laws concerning, 315.\n\n  Mental deficiency: not always inherited, 248;\n    tests for, 254, 255.\n\n  Mental organization of lower vertebrates, 205.\n\n  Mental process as neural process, 195.\n\n  Mental unsoundness, 196.\n\n  Mentality, inheritance of, 19.\n\n  Mentally disordered, cost of caring for, 257, 258.\n\n  Mercier, 279.\n\n  Merriere's disease, 117.\n\n  Metazoa, 28.\n\n  Metz, 41.\n\n  Mice, 78.\n\n  Michigan, state report on mentally defective, 234.\n\n  Migraine, 101.\n\n  Mind, relation to brain, 195.\n\n  Mitosis: 32, 33;\n    meaning of, 34, 37.\n\n  Mjoeen, 171.\n\n  Modifiability of behavior, 200, 204, 205, 207, 217, 219, 224, 225, 337.\n\n  Mongolians, 248.\n\n  Moral responsibility, 227.\n\n  Morgan, C. Lloyd, 146, 211.\n\n  Morgan, T. H., 59, 66.\n\n  Moron, 244, 268.\n\n  Morons and crime, 268.\n\n  Mosaic, heredity a, 13.\n\n  Motherhood, safeguarding, 165.\n\n  Motive, training in, 220.\n\n  Mott, 150.\n\n  Mulattoes, 92.\n\n  Multiple sclerosis, 64, 117.\n\n  Muscular atrophy: 113;\n    Gower's, 65.\n\n  Musical ability, 120.\n\n  Mutations: artificial production of, 125;\n    germinal, 125.\n\n  Mutilations, non-inheritance of, 134.\n\n  Myopia, 64.\n\n\n  Naegeli, 131.\n\n  Nam family, 271.\n\n  Natural selection partly done away with in human society, 292.\n\n  Near-sightedness, 64.\n\n  Nervous and mental diseases, 153.\n\n  Nervous organization, inheritable, 242.\n\n  Nervous response, in lower organisms, 196.\n\n  Nervous system: mainly inherited, 210, 216;\n    establishment of pathways in, 210;\n    maladjustments of, 231;\n    special developments in man, 213, 214, 215;\n    units of, 208.\n\n  Nervous systems of anthropoids, 214.\n\n  Neural pathways, not all established at birth, 217.\n\n  Neuritis optica, 65.\n\n  Neurons, 208.\n\n  Neuron theory, 208.\n\n  Neuropathic constitution, expression of, 241.\n\n  Neuropathic defects, carriers of, 253.\n\n  Neuter insects, heredity in, 136, 137.\n\n  New characters, origin of, 138.\n\n  Newman, 56.\n\n  Nicloux, 172.\n\n  Night-blindness, 65.\n\n  Nilsson-Ehle, 88, 89.\n\n  Noguchi, 186.\n\n  Nucleolus, 31.\n\n  Nucleus, structure of, 31.\n\n  Nulliplex character, 80, 100.\n\n\n  Obesity, 120, 154.\n\n  Offspring: from one parent only, 5;\n    different from either parent, 12.\n\n  Ooecyte, primary, secondary, 44.\n\n  Ooegenesis, 44.\n\n  Ooegonia, 44.\n\n  Optic nerve, atrophy of, 64.\n\n  Organs, formation of, 36.\n\n  Origin of sex cells, 12, 36.\n\n  Ovaries, transplantation of, 134.\n\n  Ovum, 26, 40.\n\n\n  Paralysis, general, 186.\n\n  Paranoia, 279.\n\n  Parent-body and germ distinct, 12.\n\n  Parenthood, cultivation of wholesome sentiment toward, 336.\n\n  Paresis: 186;\n    and crime, 279.\n\n  Parthenogenesis, 6.\n\n  Patterson, 56.\n\n  Paul, 163.\n\n  Pearson, 150, 151, 179, 296, 307.\n\n  Peas, 68, 82.\n\n  Performance tests, 256.\n\n  Peron, 133.\n\n  Personality determined by heredity, 2, 195.\n\n  Peterson, 242.\n\n  Phenotype, 86.\n\n  Phillips, 134, 135.\n\n  Phototropism, 198.\n\n  Pinard, 165.\n\n  Pineys, the, 271.\n\n  Plato, 290.\n\n  Poellman, 271.\n\n  Polar bodies, 44, 45.\n\n  Polydactyly, 108.\n\n  Potato-beetle, production of variations in, 125.\n\n  Potts, 292.\n\n  Predisposition to disease, 148.\n\n  Pregnancy, neglect of mothers during, 165.\n\n  Prenatal care: 336;\n    infection, 147;\n    influence, 11, 159, 162.\n\n  Prenuptial medical inspection desirable, 336.\n\n  Presence and absence theory: 78;\n    formulae for man, 99.\n\n  Primrose, experiments on, 125.\n\n  Principles, Mendelian, 68.\n\n  Prisoners, many mentally subnormal, 266.\n\n  Pronucleus, 47.\n\n  Protective coloration, not of somatic origin, 135, 136.\n\n  Protoplasm, germinal, 39.\n\n  Psychical development, 196, 203, 205, 206, 213, 215.\n\n  Pyramidal tracts, 214.\n\n\n  Quagga hybrid, 10.\n\n\n  Race amalgamation: 297, 298;\n    deterioration, in a selected population, 303.\n\n  Racial degeneracy, not curable by improved environment alone, 294.\n\n  Ratio: the 1:2:1, 73;\n    the 3:1, 77;\n    the 9:3:3:1, 85;\n    the 27:9:9:9:3:3:3:1, 87;\n    the 15:1, 88;\n    the 63:1, 90.\n\n  Rational behavior, 205, 206.\n\n  Reason, 206.\n\n  Recessiveness: 74;\n    in man, 115.\n\n  Records of family traits desirable, 337.\n\n  Reduction division, 41, 42.\n\n  Reflexes, 203.\n\n  Regression, law of, 17.\n\n  Renault, 172.\n\n  Rentoul, 232.\n\n  Reproduction: asexual, 6, 26;\n    sexual, 26;\n    sexual and variation, 139.\n\n  Reproductive cells, 27, 28, 29.\n\n  Responsibility for conduct, 195.\n\n  Rest, importance of, in pregnancy, 165.\n\n  Reversion: 7, 8;\n    and atavism, 8;\n    in guinea-chicken hybrids, 8.\n\n  Rheotropism, 198.\n\n  Rheumatism, 154.\n\n  Ritter, 143.\n\n  Rogers, 246, 272.\n\n  Romanes, 133.\n\n  Rosanoff, 243.\n\n  Rossolimo, 256.\n\n  Rudin, 243.\n\n\n  Salpingectomy, 322.\n\n  Sanford, 205.\n\n  St. Vitus' dance, 117.\n\n  Schulze, 24.\n\n  Schuster, 296.\n\n  Sclerosis, multiple, 64, 117.\n\n  Segregation: in dihybrids, 84;\n    Mendelian, 69, 70, 75;\n    of defectives, 318.\n\n  Seguin, 256.\n\n  Self-control, importance of, 221, 267, 268, 284, 286, 287.\n\n  Sex: and chromosomes, 59;\n    and heredity, 53;\n    cells of Volvox, 25;\n    chromosome, 57, 58;\n    determination, 55;\n    differentiation and X-element, 60;\n    evolution of, 25-30;\n    hygiene, question of school instruction in, 285;\n    in certain insects, 56;\n    linked characters, 60, 65;\n    not a necessary factor in heredity, 6;\n    problem, knowledge alone not sufficient, 286.\n\n  Sexual vice, 284.\n\n  Sharp, 322.\n\n  Simplex character, 80, 99.\n\n  Skill, non-transference in brain, 212, 213.\n\n  Skin, color of, 92.\n\n  Smallpox, 152.\n\n  Social maladies, prevention of, 293.\n\n  Softening of the brain, 186.\n\n  Soma, 28.\n\n  Spermatid, 43.\n\n  Spermatocyte, primary, secondary, 43.\n\n  Spermatogenesis, 42.\n\n  Spermatogonium, 43.\n\n  Spermatazoon: 26, 40;\n    a cell, 22;\n    formation of, 43;\n    structure of, 43.\n\n  Spindle, in cell-division, 32.\n\n  Spottedness of hair-coat, 113.\n\n  Sprague, 281, 305.\n\n  Starfish, training a, 204.\n\n  Statistical methods, 15.\n\n  Statistics, trustworthy needed, 334.\n\n  Stature, inheritance of, 17.\n\n  Stereotropism, 198.\n\n  Sterility, 182.\n\n  Sterilization: 322;\n    in epilepsy, 326;\n    laws, 323;\n    laws, on trial, 329;\n    laws, states having, 327.\n\n  Stevens, 41.\n\n  Stockard, 174-178.\n\n  Strength, muscular, 120.\n\n  Stripes, reversionary, 8.\n\n  Stutzman, 305.\n\n  Sullivan, 168.\n\n  Superior strains, conservation of, 157.\n\n  Synapse, 210.\n\n  Synapsis, 41, 42.\n\n  Syndactyly, 65, 108, 111.\n\n  Syphilis: 184-190;\n    and prostitutes, 185;\n    cerebro-spinal form, 189-190;\n    prenuptial inspection for, 190-192;\n    prevalence, 186;\n    stages of, 185;\n    tests for, 188.\n\n  Syphilitics: children of, 187, 188;\n    married, 190.\n\n\n  Tabes dorsalis, 186.\n\n  Taints, 101.\n\n  Talent, inheritance of, 212.\n\n  Taylor, 297.\n\n  Telegony, alleged cases of, 10.\n\n  Temperament, inheritance of, 19.\n\n  Thermotropism, 198.\n\n  Thigmotropism, 198.\n\n  Third generation, segregation in, 69.\n\n  Thomsen's disease, 118.\n\n  Thomson, 55.\n\n  Thorndike, 296.\n\n  Tower, 125.\n\n  Training of children: and heredity, 218;\n    faults in, 221, 222.\n\n  Transmission, not necessarily inheritance, 163.\n\n  Tredgold, 170.\n\n  Treponema pallidum, 185.\n\n  Tribe of Ishmael, 271.\n\n  Tropic responses: often purposeful, 201;\n    uncertainties in, 202.\n\n  Tropisms: 197;\n    complications in, 200;\n    in plants and animals, 198;\n    relations to reflex actions and instincts, 203.\n\n  Tschermak, 68.\n\n  Tuberculosis, 118, 148-160, 162.\n\n  Twins: identical, 55;\n    sex of, 55.\n\n  Typhoid, 152.\n\n\n  Unemployed, frequently morons, 280.\n\n  Unfit, elimination of, urgent, 313.\n\n  Unit-character: 12;\n    inheritance of, 13.\n\n  Unicellular organisms: 21;\n    inheritance in, 22, 23.\n\n  Use and disuse, 122.\n\n\n  Van Ingen, 167.\n\n  Vasectomy, 322.\n\n  Venereal disease, 182.\n\n  Virchow, 147.\n\n  Voison, 133.\n\n  Volitions as tropisms, 199.\n\n  Volvox, 25, 26, 27.\n\n\n  War, eugenical effects of, 299.\n\n  Wasserman, provocative, 189.\n\n  Wasserman test, 188, 189.\n\n  Webbed digits, 65.\n\n  Weeks, 251, 252, 253, 291.\n\n  West, 167.\n\n  Wheat, 75, 81, 88.\n\n  Whetham, 314, 316.\n\n  Whitman, 145.\n\n  Wilmarth, 243, 245, 274, 291.\n\n  Wilson, 59, 62, 94, 95.\n\n  Woods, 296.\n\n\n  X-element, 57, 58.\n\n\n  Zebra hybrids, 10.\n\n  Zeros, the, 271.\n\n  Zygote: 26, 27;\n    chromosomes of, 40.\n\n\n\n\nFOOTNOTES:\n\n[1] The reader desiring more detailed information will find fuller\ndiscussions in the following:\n\nWilson, E. B.: _Recent Researches on the Determination and Heredity of\nSex_. Science, January 8, 1909.\n\nWilson, E. B.: _The Chromosomes in Relation to the Determination of Sex_.\nScience Progress, April, 1910.\n\nGuyer, M. F.: _Recent Progress in Some Lines of Cytology_. Transactions of\nthe American Microscopical Society, April, 1911.\n\nMorgan, T. H.: _Heredity and Sex_. Columbia University Press, 1913.\n\n[2] A translation of Mendel's original papers will be found in _Mendel's\nPrinciples of Heredity_, by W. Bateson.\n\n[3] _Heredity of Skin Color in Negro and White Crosses_: Publication No.\n188, of the _Carnegie Institution of Washington_.\n\n[4] Whitman, C. O.: _Animal Behavior, Biological Lectures_, Marine\nBiological Laboratory, 1898.\n\n[5] _The Fight Against Tuberculosis and the Death Rate from Phthisis_,\nLondon, Dulau & Co., 1911.\n\n[6] Forel, August: _The Sexual Question_, p. 268.\n\n[7] Loc. cit. p. 251.\n\n[8] In this connection it is instructive to note from a Michigan state\nreport, just off the press, that, among 4,917 insane individuals\nconcerning whom satisfactory information was obtained, 65.4 per cent. \"had\namong their ancestors or family such hereditary influences as insanity,\napoplexy or paralysis, psychopathic abnormalities or alcoholism.\" See\n_Report of the Commission to Investigate the Extent of Feeble-mindedness,\nEpilepsy, Insanity and Other Conditions of Mental Defectiveness in\nMichigan_. Wynkoop Hollenbeck Crawford Co., State Printers, Lansing,\nMichigan, 1915.\n\n[9] _Feeble-mindedness; Its Causes and Consequences_, by Henry H. Goddard,\nThe Macmillan Company, 1914.\n\n[10] _The Binet-Simon Measuring Scale for Intelligence_, by Henry H.\nGoddard, 1911. The Training School, Vineland, N. J. Price 15 cents.\n\n[11] \"Tests for Mental Defects,\" by Howard A. Knox, _Journal of Heredity_,\nMarch, 1914. See also Knox: _Journal of the American Medical Association_,\n1914.\n\n[12] _The Individual Delinquent_, by William Healy, M. D. Little, Brown &\nCo., Boston.\n\n[13] _The Individual Delinquent_, by William Healy, M. D. Little, Brown &\nCo., Boston.\n\n[14] The Psycopathic Laboratory in connection with the Juvenile Court of\nChicago.\n\n[15] See \"The Foreign Born in the United States.\" _The National Geographic\nMagazine_, September, 1914.\n\n[16] See First Report of the Committee of the Eugenic Section of the\nAmerican Breeders' Association, \"On Immigration\", _American Breeders'\nMagazine_, Vol. III, No. 4, 1912. Also Second Report of same, _The Journal\nof Heredity_, July, 1914.\n\n[17] \"The Negro and His Health Problems,\" _Medical Record_, September 12,\n1912.\n\n[18] See D. S. Jordan, _The Human Harvest_, or V. L. Kellogg, _Eugenics\nand Militarism_.\n\n[19] For arguments indicating the superior eugenical fitness of college\ngraduates see \"Wellesley's Birth-Rate,\" by Roswell H. Johnson and Bertha\nStutzman, _The Journal of Heredity_, June, 1915. See also, \"Education and\nRace Suicide,\" by Robert J. Sprague, _ibid._, April, 1915.\n\n[20] Since the present manuscript went to press an excellent government\nreport (_Insane and Feeble-Minded in Institutions in 1910_, Department of\nCommerce, Bureau of the Census, 1914, Washington, D. C.) has appeared. In\nit one finds the estimate that not over one-tenth of our feeble-minded are\nbeing cared for in special institutions.\n\n[21] For summaries of existing sterilization laws and statements of the\nissues involved see (1) _The Legal, Legislative, and Administrative\nAspects of Sterilisation_, Bulletin 10B, February 3, 1914, Eugenics Record\nOffice, Cold Spring Harbor, N. Y.; (2) _Sterilisation of Criminals_,\nReport of Committee H of the American Institute of Criminal Law and\nCriminology, Bulletin No. XV, September, 1914.\n\n\n\n\nTranscriber's Notes:\n\nPassages in italics are indicated by _italics_.\n\nPassages in bold are indicated by =bold=.\n\nSuperscripted characters are indicated by ^{superscript}.\n\nSubscripted characters are indicated by _{subscript}.\n\nThe original text contains a few letters with diacritical marks that are\nnot represented in this text version.\n\nThe original text contains male and female symbols. These are represented\nas [male] and [female].","title":"Being Well-Born: An Introduction to Eugenics","tradition":"philosophy-ethics","translated_text":null,"word_count":91982}