{"collection":"philosophy-ethics","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_18911/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_18911","id":"gutenberg_18911","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/18911","summary":null,"tags":["Biology","Category: Philosophy & Ethics","Category: Science - Biology"],"text":"Produced by Frank van Drogen, Jeannie Howse and the Online\nDistributed Proofreading Team at http://www.pgdp.net (This\nbook was produced from scanned images of public domain\nmaterial from the Google Print project.)\n\n\n\n\n\n\n\n\n\n\nBIOLOGY\n\nBY\n\nEDMUND BEECHER WILSON\nPROFESSOR OF ZOOLOGY\nCOLUMBIA UNIVERSITY\n\n\n\nNew York\nTHE COLUMBIA UNIVERSITY PRESS\n1908\n\n\n\n\n  BIOLOGY\n\n  A LECTURE DELIVERED AT COLUMBIA UNIVERSITY\n  IN THE SERIES ON SCIENCE, PHILOSOPHY AND ART\n  NOVEMBER 20, 1907\n\n\n\n\nBIOLOGY\n\nBY\n\nEDMUND BEECHER WILSON\nPROFESSOR OF ZOOLOGY\nCOLUMBIA UNIVERSITY\n\n\n\nNew York\nTHE COLUMBIA UNIVERSITY PRESS\n1908\n\n\n\n\nCOPYRIGHT, 1908,\nby THE COLUMBIA UNIVERSITY PRESS.\n\nSet up, and published March, 1908.\n\n\n\n\nBIOLOGY\n\n\nI must at the outset remark that among the many sciences that are\noccupied with the study of the living world there is no one that may\nproperly lay exclusive claim to the name of Biology. The word does\nnot, in fact, denote any particular science but is a generic term\napplied to a large group of biological sciences all of which alike are\nconcerned with the phenomena of life. To present in a single address,\neven in rudimentary outline, the specific results of these sciences is\nobviously an impossible task, and one that I have no intention of\nattempting. I shall offer no more than a kind of preface or\nintroduction to those who will speak after me on the biological\nsciences of physiology, botany and zoology; and I shall confine it to\nwhat seem to me the most essential and characteristic of the general\nproblems towards which all lines of biological inquiry must sooner or\nlater converge.\n\nIt is the general aim of the biological sciences to learn something of\nthe order of nature in the living world. Perhaps it is not amiss to\nremark that the biologist may not hope to solve the ultimate problems\nof life any more than the chemist and physicist may hope to penetrate\nthe final mysteries of existence in the non-living world. What he can\ndo is to observe, compare and experiment with phenomena, to resolve\nmore complex phenomena into simpler components, and to this extent, as\nhe says, to \"explain\" them; but he knows in advance that his\nexplanations will never be in the full sense of the word final or\ncomplete. Investigation can do no more than push forward the limits of\nknowledge.\n\nThe task of the biologist is a double one. His more immediate effort is\nto inquire into the nature of the existing organism, to ascertain in\nwhat measure the complex phenomena of life as they now appear are\ncapable of resolution into simpler factors or components, and to\ndetermine as far as he can what is the relation of these factors to\nother natural phenomena. It is often practically convenient to consider\nthe organism as presenting two different aspects--a structural or\nmorphological one, and a functional or physiological--and biologists\noften call themselves accordingly morphologists or physiologists.\nMorphological investigation has in the past largely followed the method\nof observation and comparison, physiological investigation that of\nexperiment; but it is one of the best signs of progress that in recent\nyears the fact has come clearly into view that morphology and\nphysiology are really inseparable, and in consequence the distinctions\nbetween them, in respect both to subject matter and to method, have\nlargely disappeared in a greater community of aim. Morphology and\nphysiology alike were profoundly transformed by the introduction into\nbiological studies of the genetic or historical point of view by\nDarwin, who did more than any other to establish the fact, suspected by\nmany earlier naturalists, that existing vital phenomena are the outcome\nof a definite process of evolution; and it was he who first fully\nbrought home to us how defective and one-sided is our view of the\norganism so long as we do not consider it as a product of the past. It\nis the second and perhaps greater task of the biologist to study the\norganism from the historical point of view, considering it as the\nproduct of a continuous process of evolution that has been in operation\nsince life began. In its widest scope this genetic inquiry involves\nnot only the evolution of higher forms from lower ones, but also the\nstill larger question of the primordial relation of living things to\nthe non-living world. Here is involved the possibility so strikingly\nexpressed many years ago by Tyndall in that eloquent passage in the\nBelfast address, where he declared himself driven by an intellectual\nnecessity to cross the boundary line of the experimental evidence and\nto discern in non-living matter, as he said, the promise and potency of\nevery form and quality of terrestrial life. This intellectual necessity\nwas created by a conviction of the continuity and consistency of\nnatural phenomena, which is almost inseparable from the scientific\nattitude towards nature. But Tyndall's words stood after all for a\nconfession of faith, not for a statement of fact; and they soared far\nabove the _terra firma_ of the actual evidence. At the present day we\ntoo may find ourselves logically driven to the view that living things\nfirst arose as a product of non-living matter. We must fully recognize\nthe extraordinary progress that has been made by the chemist in the\nartificial synthesis of compounds formerly known only as the direct\nproducts of living protoplasm. But it must also be admitted that we are\nstill wholly without evidence of the origin of any living thing, at any\nperiod of the earth's history, save from some other living thing; and\nafter more than two centuries Redi's aphorism _omne vivum e vivo_\nretains to-day its full force. It is my impression therefore that the\ntime has not yet come when hypotheses regarding a different origin of\nlife can be considered as practically useful.\n\nIf I have the temerity to ask your attention to the fundamental\nproblem towards which all lines of biological inquiry sooner or later\nlead us it is not with the delusion that I can contribute anything new\nto the prolonged discussions and controversies to which it has given\nrise. I desire only to indicate in what way it affects the practical\nefforts of biologists to gain a better understanding of the living\norganism, whether regarded as a group of existing phenomena or as a\nproduct of the evolutionary process; and I shall speak of it, not in\nany abstract or speculative way, but from the standpoint of the\nworking naturalist. The problem of which I speak is that of organic\nmechanism and its relation to that of organic adaptation. How in\ngeneral are the phenomena of life related to those of the non-living\nworld? How far can we profitably employ the hypothesis that the living\nbody is essentially an automaton or machine, a configuration of\nmaterial particles, which, like an engine or a piece of clockwork,\nowes its mode of operation to its physical and chemical construction?\nIt is not open to doubt that the living body _is_ a machine. It is a\ncomplex chemical engine that applies the energy of the food-stuffs to\nthe performance of the work of life. But is it something more than a\nmachine? If we may imagine the physico-chemical analysis of the body\nto be carried through to the very end, may we expect to find at last\nan unknown something that transcends such analysis and is neither a\nform of physical energy nor anything given in the physical or chemical\nconfiguration of the body? Shall we find anything corresponding to the\nusual popular conception--which was also along the view of\nphysiologists--that the body is \"animated\" by a specific \"vital\nprinciple,\" or \"vital force,\" a dominating \"archaeus\" that exists only\nin the realm of organic nature? If such a principle exists, then the\nmechanistic hypothesis fails and the fundamental problem of biology\nbecomes a problem _sui generis_.\n\nIn its bearing on man's place in nature this question is one of the\nmost momentous with which natural science has to deal, and it has\noccupied the attention of thinking men in every age. I cannot trace\nits history, but it will be worth our while to place side by side the\nwords of three of the great leaders of modern scientific and\nphilosophic thought. The saying has been attributed to Descartes,\n\"Give me matter and I will construct the world\"--meaning by this the\nliving world as well as the non-living; but Descartes specifically\nexcepted the human mind. I do not know whether the great French\nphilosopher actually used these particular words, but they express the\nessence of the mechanistic hypothesis that he adopted. Kant utterly\nrepudiated such a conception in the following well known passage: \"It\nis quite certain that we cannot become adequately acquainted with\norganized creatures and their hidden potentialities by means of the\nmerely mechanical principles of nature, much less can we explain them;\nand this is so certain that we may boldly assert that it is absurd for\nman even to make such an attempt or to hope that a Newton may one day\narise who will make the production of a blade of grass comprehensible\nto us according to natural laws that have not been ordered by design.\nSuch an insight we must absolutely deny to man.\" Still, in another\nplace Kant admitted that the facts of comparative anatomy give us \"a\nray of hope, however faint, that something may be accomplished by the\naid of the principle of the mechanism of nature, without which there\ncan be no science in general.\" It is interesting to turn from this to\nthe bold and aggressive assertion of Huxley: \"Living matter differs\nfrom other matter in degree and not in kind, the microcosm repeats the\nmacrocosm; and one chain of causation connects the nebulous origin of\nsuns and planetary systems with the protoplasmic foundations of life\nand organization.\"\n\nDo not expect me to decide where such learned doctors disagree; but I\nwill at this point venture on one comment which may sound the key-note\nof this address. Perhaps we shall find that in the long run and in the\nlarge sense Kant was right; but it is certain that to-day we know\nvery much more about the formation of the living body, whether a blade\nof grass or a man, than did the naturalists of Kant's time; and for\nbetter or for worse the human mind seems to be so constituted that it\nwill continue its efforts to explain such matters, however difficult\nthey may seem to be. But I return to our more specific inquiry with\nthe remark that the history of physiology in the past two hundred\nyears has been the history of a progressive restriction of the notion\nof a \"vital force\" or \"vital principle\" within narrower and narrower\nlimits, until at present it may seem to many physiologists that no\nroom for it remains within the limits of our biological philosophy.\nOne after another the vital activities have been shown to be in\ngreater or less degree explicable or comprehensible considered as\nphysico-chemical operations of various degrees of complexity. Every\nphysiologist will maintain that we cannot name one of these\nactivities, not even thought, that is not carried on by a physical\nmechanism. He will maintain further that in most cases the vital\nactions are not merely accompanied by physico-chemical operations but\nactually consist of them; and he may go so far as definitely to\nmaintain that we have no evidence that life itself can be regarded as\nanything more than their sum total. He is able to bring forward cogent\nevidence that all modes of vital activity are carried on by means of\nenergy that is set free in protoplasm or its products by means of\ndefinite chemical processes collectively known as metabolism. When the\nmatter is reduced to its lowest terms, life, as thus viewed, seems to\nhave its root in chemical change; and we can understand how an eminent\nGerman physiologist offers us a definition or characterization of life\nthat runs: \"The life-process consists in the metabolism of proteids.\"\nI ask your particular attention to this definition since I now wish to\ncontrast with it another and very different one.\n\nI shall introduce it to your attention by asking a very simple\nquestion. We may admit that digestion, for example, is a purely\nchemical operation, and one that may be exactly imitated outside the\nliving body in a glass flask. My question is, how does it come to pass\nthat an animal has a stomach?--and, pursuing the inquiry, how does it\nhappen that the human stomach is practically incapable of digesting\ncellulose, while the stomachs of some lower animals, such as the goat,\nreadily digest this substance? The earlier naturalists, such as\nLinnaeus, Cuvier or Agassiz, were ready with a reply which seemed so\nsimple, adequate and final that the plodding modern naturalist cannot\nrepress a feeling of envy. In their view plants and animals are made\nas they were originally created, each according to its kind. The\nbiologist of to-day views the matter differently; and I shall give his\nanswer in the form in which I now and then make it to a student who\nmay chance to ask why an insect has six legs and a spider eight, or\nwhy a yellowbird is yellow and a bluebird blue. The answer is: \"For\nthe same reason that the elephant has a trunk.\" I trust that a certain\nrugged pedagogical virtue in this reply may atone for its lack of\nelegance. The elephant has a trunk, as the insect has six legs, for\nthe reason that such is the specific nature of the animal; and we may\nassert with a degree of probability that amounts to practical\ncertainty that this specific nature is the outcome of a definite\nevolutionary process, the nature and causes of which it is our\ntremendous task to determine to such extent as we may be able. But\nthis does not yet touch the most essential side of the problem. What\nis most significant is that the clumsy, short-necked elephant has been\nendowed--\"by nature,\" as we say--with precisely such an organ, the\ntrunk, as he needs to compensate for his lack of flexibility and\nagility in other respects. If we are asked _why_ the elephant has a\ntrunk, we must answer because the animal needs it. But does such a\nreply in itself explain the fact? Evidently not. The question which\nscience must seek to answer, is _how_ came the elephant to have a\ntrunk; and we do not properly answer it by saying that it has\ndeveloped in the course of evolution. It has been well said that even\nthe most complete knowledge of the genealogy of plants and animals\nwould give us no more than an ancestral portrait-gallery. We must\ndetermine the causes and conditions that have cooperated to produce\nthis particular result if our answer is to constitute a true\nscientific explanation. And evidently he who adopts the machine-theory\nas a general interpretation of vital phenomena must make clear to us\nhow the machine was built before we can admit the validity of his\ntheory, even in a single case. Our apparently simple question as to\nwhy the animal has a stomach has thus revealed to us the full\nmagnitude of the task with which the mechanist is confronted; and it\nhas brought us to that part of our problem that is concerned with the\nnature and origin of organic adaptations. Without tarrying to attempt\na definition of adaptation I will only emphasize the fact that many of\nthe great naturalists, from Aristotle onward, have recognized the\npurposeful or design-like quality of vital phenomena as their most\nessential and fundamental characteristic. Herbert Spencer defined life\nas the continuous _adjustment_ of internal relations to external\nrelations. It is one of the best that has been given, though I am not\nsure that Professor Brooks has not improved upon it when he says that\nlife is \"response to the order of nature.\" This seems a long way from\nthe definition of Verworn, heretofore cited, as the \"metabolism of\nproteids.\" To this Brooks opposes the telling epigram: \"The essence of\nlife is not protoplasm but purpose.\"\n\nWithout attempting adequately to illustrate the nature of organic\nadaptations, I will direct your attention to what seems to me one of\ntheir most striking features regarded from the mechanistic position.\nThis is the fact that adaptations so often run counter to direct or\nobvious mechanical conditions. Nature is crammed with devices to\nprotect and maintain the organism against the stress of the\nenvironment. Some of these are given in the obvious structure of the\norganism, such as the tendrils by means of which the climbing plant\nsustains itself against the action of gravity or the winds, the\nprotective shell of the snail, the protective colors and shapes of\nanimals, and the like. Any structural feature that is useful because\nof its construction is a structural adaptation; and when such\nadaptations are given the mechanist has for the most part a relatively\neasy task in his interpretation. He has a far more difficult knot to\ndisentangle in the case of the so-called functional adaptations, where\nthe organism modifies its activities (and often also its structure) in\nresponse to changed conditions. The nature of these phenomena may be\nillustrated by a few examples so chosen as to form a progressive\nseries. If a spot on the skin be rubbed for some time the first result\nis a direct and obviously mechanical one; the skin is worn away. But\nif the rubbing be continued long enough, and is not too severe, an\nindirect effect is produced that is precisely the opposite of the\ninitial direct one; the skin is replaced, becomes thicker than before,\nand a callus is produced that protects the spot from further injury.\nThe healing of a wound involves a similar action. Again, remove one\nkidney or one lung and the remaining one will in time enlarge to\nassume, as far as it is able, the functions of both. If the leg of a\nsalamander or a lobster be amputated, the wound not only heals but a\nnew leg is regenerated in place of that which has been lost. If a\nflatworm be cut in two, the front piece grows out a new tail, the hind\npiece a new head, and two perfect worms result. Finally, it has been\nfound in certain cases, including animals as highly organized as\nsalamanders, that if the egg be separated into two parts at an early\nperiod of development each part develops into a perfect embryo animal\nof half the usual size, and a pair of twins results. In each of these\ncases the astonishing fact is that a mechanical injury sets up in the\norganism a complicated adaptive response in the form of operations\nwhich in the end counteract the initial mechanical effect. It is no\ndoubt true that somewhat similar self-adjustments or responses may be\nsaid to take place in certain non-living mechanical systems, such as\nthe spinning top or the gyroscope; but those that occur in the living\nbody are of such general occurrence, of such complexity and variety,\nand of so design-like a quality, that they may fairly be regarded as\namong the most characteristic of the vital activities. It is precisely\nthis characteristic of many vital phenomena that renders their\naccurate analysis so difficult and complex a task; and it is largely\nfor this reason that the biological sciences, as a whole, still stand\nfar behind the physical sciences, both in precision and in\ncompleteness of analysis.\n\nWhat is the actual working attitude of naturalists towards the general\nproblem that I have endeavored to outline? It would be a piece of\npresumption for me to speak for the body of working biologists, and I\nwill therefore speak for only one of them. It is my own conviction\nthat whatever be the difficulties that the mechanistic hypothesis has\nto face, it has established itself as the most useful working\nhypothesis that we can at present employ. I do not mean to assert that\nit is adequate, or even true. I believe only that we should make use\nof it as a working program, because the history of biological research\nproves it to have been a more effective and fruitful means of\nadvancing knowledge than the vitalistic hypothesis. We should\ntherefore continue to employ it for this purpose until it is clearly\nshown to be untenable. Whether we must in the end adopt it will\ndepend on whether it proves the simplest hypothesis in the large\nsense, the one most in harmony with our knowledge of nature in\ngeneral. If such is the outcome, we shall be bound by a deeply lying\ninstinct that is almost a law of our intellectual being to accept it,\nas we have accepted the Copernican system rather than the Ptolemaic. I\nbelieve I am right in saying that the attitude I have indicated as a\nmore or less personal one is also that of the body of working\nbiologists, though there are some conspicuous exceptions.\n\nIn endeavoring to illustrate how this question actually affects\nresearch I will offer two illustrative cases, one of which may\nindicate the fruitfulness of the mechanistic conception in the\nanalysis of complex and apparently mysterious phenomena, the other the\nnature of the difficulties that have in recent years led to attempts\nto re-establish the vitalistic view. The first example is given by the\nso-called law or principle of Mendel in heredity. The principle\nrevealed by Mendel's wonderful discovery is not shown in all the\nphenomena of heredity and is probably of more or less limited\napplication. It possesses however a profound significance because it\ngives almost a demonstration that a definite, and perhaps a relatively\nsimple, mechanism must lie behind the phenomena of heredity in\ngeneral. Hereditary characters that conform to this law undergo\ncombinations, disassociations and recombinations which in certain way\nsuggest those that take place in chemical reactions; and like the\nlatter they conform to definite quantitative rules that are capable of\narithmetical formulation. This analogy must not be pressed too far;\nfor chemical reactions are individually definite and fixed, while\nthose of the hereditary characters involve a fortuitous element of\nsuch a nature that the numerical result is not fixed or constant in\nthe individual case but follows the law of probability in the\naggregate of individuals. Nevertheless, it is possible, and has\nalready become the custom, to designate the hereditary organization by\nsymbols or formulas that resemble those of the chemist in that they\nimply the _quantitative_ results of heredity that follow the union of\ncompounds of known composition. Quantitative prediction--not precisely\naccurate, but in accordance with the law of probability--has thus\nbecome possible to the biological experimenter on heredity. I will\ngive one example of such a prediction made by Professor Cuenot in\nexperimenting on the heredity of color in mice (see the following\ntable). The experiment extended through three generations. Of the four\ngrandparents three were pure white albinos, identical in outward\nappearance, but of different hereditary capacity, while the fourth was\na pure black mouse. The first pair of grandparents consisted of an\nalbino of gray ancestry, AG, and one of black ancestry, AB. The second\npair consisted of an albino of yellow ancestry, AY, and a black mouse,\nCB. The result of the first union, AG x AB is to produce again pure\nwhite mice of the composition AGAB. The second union, AY x CB is to\nproduce mice that appear pure _yellow_, and have the formula AYCB.\nWhat, now, will be the result of uniting the two forms thus\nproduced--_i.e._ AGAB x AYCB? Cuenot's prediction was that they should\nyield eight different kinds of mice, of which four should be white,\ntwo yellow, one black and one gray. The actual aggregate result of\nsuch unions, repeatedly performed, compared with the theoretic\nexpectation, is shown in the foregoing table. As will be seen, the\ncorrespondence, though close, is not absolutely exact, yet is near\nenough to prove the validity of the principle on which the prediction\nwas based, and we may be certain that had a much larger number of\nthese mice been reared the correspondence would have been still\ncloser. I have purposely selected a somewhat complicated example, and\ntime will not admit of a full explanation of the manner in which this\nparticular result was reached. I will however attempt to give an\nindication of the general Mendelian principle by means of which\npredictions of this kind are made. This principle appears in its\nsimplest form in the behavior of two contrasting characters of the\nsame general type--for instance two colors, such as gray and white in\nmice. If two animals, which show respectively two such characters are\nbred together, only one of the characters (known as the \"dominant\")\nappears in the offspring, while the other (known as the \"recessive\")\ndisappears from view. In the next generation, obtained by breeding\nthese hybrids together, both characters appear separately and in a\ndefinite ratio, there being in the long run three individuals that\nshow the dominant character to one that shows the recessive. Thus, in\nthe case of gray and white mice, the first cross is always gray, while\nthe next generation includes three grays to one white. This is the\nfundamental Mendelian ratio for a single pair of characters; and from\nit may readily be deduced the more complicated combinations that\nappear when two or more pairs of characters are considered together.\nSuch combinations appear in definite series, the nature of which may\nbe worked out by a simple method of binomial expansion. By the use of\nthis principle astonishingly accurate numerical predictions may be\nmade, even of rather complex combinations; and furthermore, new\ncombinations may be, and have been, artificially produced, the number,\ncharacter and hereditary capacity of which are known in advance. The\nfundamental ratio for a single pair of characters is explained by a\nvery simple assumption. When a dominant and a recessive character are\nassociated in a hybrid, the two must undergo in some sense a\ndisjunction or separation in the formation of the germ-cells of the\nhybrid. This takes place in a quite definite way, exactly half the\ngerm-cells in each sex receiving the potentiality of the dominant\ncharacter, the other half the potentiality of the recessive. This is\nroughly expressed by saying that the germ-cells are no longer hybrid,\nlike the body in which they arise, but bear one character or the\nother; and although in a technical sense this is probably not\nprecisely accurate, it will sufficiently answer our purpose. If, now,\nit be assumed that fertilization takes place fortuitously--that is\nthat union is equally probable between germ-cells bearing the same\ncharacter and those bearing opposite characters,--the observed\nnumerical ratio in the following generation follows according to the\nlaw of probability. Thus is explained both the fortuitous element that\ndifferentiates these cases from exact chemical combinations, and the\ndefinite numerical relations that appear in the aggregate of\nindividuals.\n\n\n  Grandparents AG (white) AB (white)  AY (white) CB (black)\n                |         |           |           |\n                +---------+           +-----------+\n                     |                      |\n  Parents     AGAB (white)              AYCB (yellow)\n                     |                      |\n                     +----------------------+\n                                |              Observed    Calculated\n                             {AGAY}\n                             {ABAY}     (White)    81         76\n                             {AGAB}\n   Offspring  ---------------{ABAB}\n                             {\n                             {AGCY}    (Yellow)    34         38\n                             {ABCY}\n                             {\n                             {ABCB      (Black)    20         19\n                             {AGCB       (Gray)    16         19\n                                                  ----       ----\n                                                  151        152\n\n\nNow, the point that I desire to emphasize is that one or two very\nsimple mechanistic assumptions give a luminously clear explanation of\nthe behavior of the hereditary characters according to Mendel's law,\nand at one stroke bring order out of the chaos in which facts of this\nkind at first sight seem to be. Not less significant is the fact that\ndirect microscopical investigation is actually revealing in the\ngerm-cells a physical mechanism that seems adequate to explain the\ndisjunction of characters on which Mendel's law depends; and this\nmechanism probably gives us also at least a key to the long standing\nriddle of the determination and heredity of sex. These phenomena are\ntherefore becoming intelligible from the mechanistic point of view.\nFrom any other they appear as an insoluble enigma. When such progress\nas this is being made, have we not a right to believe that we are\nemploying a useful working hypothesis?\n\nBut let us now turn to a second example that will illustrate a class\nof phenomena which have thus far almost wholly eluded all attempts to\nexplain them. The one that I select is at present one of the most\nenigmatical cases known, namely, the regeneration of the lens of the\neye in the tadpoles of salamanders. If the lens be removed from the\neye of a young tadpole, the animal proceeds to manufacture a new one\nto take its place, and the eye becomes as perfect as before. That such\na process should take place at all is remarkable enough; but from a\ntechnical point of view this is not the extraordinary feature of the\ncase. What fills the embryologist with astonishment is the fact that\nthe new lens is not formed in the same way or from the same material\nas the old one. In the normal development of the tadpole from the egg,\nas in all other vertebrate animals, the lens is formed from the outer\nskin or ectoderm of the head. In the replacement of the lens after\nremoval it arises from the cells of the iris, which form the edge of\nthe optic cup, and this originates in the embryo not from the outer\nskin but as an outgrowth from the brain. As far as we can see, neither\nthe animal itself nor any of its ancestors can have had experience of\nsuch a process. How, then, can such a power have been acquired, and\nhow does it inhere in the structure of the organism? If the process of\nrepair be due to some kind of intelligent action, as some naturalists\nhave supposed, why should not the higher animals and man possess a\nsimilar useful capacity? To these questions biology can at present\ngive no reply. In the face of such a case the mechanist must simply\nconfess himself for the time being brought to a standstill; and there\nare some able naturalists who have in recent years argued that by the\nvery nature of the case such phenomena are incapable of a rational\nexplanation along the lines of a physico-chemical or mechanistic\nanalysis. These writers have urged, accordingly, that we must\npostulate in the living organism some form of controlling or\nregulating agency which does not lie in its physico-chemical\nconfiguration and is not a form of physical energy--something that may\nbe akin to a form of intelligence (conscious or unconscious), and to\nwhich the physical energies are in some fashion subject. To this\nsupposed factor in the vital processes have been applied such terms as\nthe \"entelechy\" (from Aristotle), or the \"psychoid\"; and some writers\nhave even employed the word \"soul\" in this sense--though this\ntechnical and limited use of the word should not be confounded with\nthe more usual and general one with which we are familiar. Views of\nthis kind represent a return, in some measure, to earlier vitalistic\nconceptions, but differ from the latter in that they are an outcome of\ndefinite and exact experimental work. They are therefore often spoken\nof collectively as \"neo-vitalism.\"\n\nIt is not my purpose to enter upon a detailed critique of this\ndoctrine. To me it seems not to be science, but either a kind of\nmetaphysics or an act of faith. I must own to complete inability to\nsee how our scientific understanding of the matter is in any way\nadvanced by applying such names as \"entelechy\" or \"psychoid\" to the\nunknown factors of the vital activities. They are words that have been\nwritten into certain spaces that are otherwise blank in our record of\nknowledge, and as far as I can see no more than this. It is my\nimpression that we shall do better as investigators of natural\nphenomena frankly to admit that they stand for matters that we do not\nyet understand, and continue our efforts to make them known. And have\nwe any other way of doing this than by observation, experiment,\ncomparison and the resolution of more complex phenomena into simpler\ncomponents? I say again, with all possible emphasis, that the\nmechanistic hypothesis or machine-theory of living beings is not fully\nestablished, that it _may_ not be adequate or even true; yet I can\nonly believe that until every other possibility has realty been\nexhausted scientific biologists should hold fast to the working\nprogram that has created the sciences of biology. The vitalistic\nhypothesis may be held, and is held, as a matter of faith; but we\ncannot call it science without misuse of the word.\n\nWhen we turn, finally, to the genetic or historical part of our task,\nwe find ourselves confronted with precisely the same general problem\nas in case of the existing organism. Biological investigators have\nlong since ceased to regard the fact of organic evolution as open to\nserious discussion. The transmutation of species is not an hypothesis\nor assumption, it is a fact accurately observed in our laboratories;\nand the theory of evolution is only questioned in the same very\ngeneral way in which all the great generalizations of science are held\nopen to modification as knowledge advances. But it is a very large\nquestion what has caused and determined evolution. Here, too, the\nfundamental problem is, how far the process may be mechanically\nexplicable or comprehensible, how far it is susceptible of formulation\nin physico-chemical or mechanistic terms. The most essential part of\nthis problem relates to the origin of organic adaptations, the\nproduction of the fit. With Kant, Cuvier and Linnaeus believed this\nproblem scientifically insoluble. Lamarck attempted to find a solution\nin his theory of the inheritance of the effects of use, disuse and\nother \"acquired characters\"; but his theory was insecurely based and\nalso begged the question, since the power of adaptation through which\nuse, disuse and the like produce their effects is precisely that which\nmust be explained. Darwin believed he had found a partial solution in\nhis theory of natural selection, and he was hailed by Haeckel as the\nbiological Newton who had set at naught the _obiter dictum_ of Kant.\nBut Darwin himself did not consider natural selection as an adequate\nexplanation, since he called to its aid the subsidiary hypotheses of\nsexual selection and the inheritance of acquired characters. If I\ncorrectly judge, the first of these hypotheses must be considered as\nof limited application if it is not seriously discredited, while the\nsecond can at best receive the Scotch verdict, not proven. In any\ncase, natural selection must fight its own battles.\n\nLatter day biologists have come to see clearly that the inadequacy of\nnatural selection lies in its failure to explain the origin of the\nfit; and Darwin himself recognized clearly enough that it is not an\noriginative or creative principle. It is only a condition of survival,\nand hence a condition of progress. But whether we conceive with Darwin\nthat selection has acted mainly upon slight individual variations, or\nwith DeVries that it has operated with larger and more stable\nmutations, any adequate general theory of evolution must explain the\norigin of the fit. Now, under the theory of natural selection, pure\nand simple, adaptation or fitness has a merely casual or accidental\ncharacter. In itself the fit has no more significance than the unfit.\nIt is only one out of many possibilities of change, and evolution by\nnatural selection resolves itself into a series of lucky accidents.\nFor Agassiz or Cuvier the fit is that which was designed to fit. For\nnatural selection, pure and simple, the fit is that which happens to\nfit. I, for one, am unable to find a logical flaw in this conception\nof the fit; and perhaps we may be forced to accept it as sufficient.\nBut I believe that naturalists do not yet rest content with it. Darwin\nhimself was repeatedly brought to a standstill, not merely by specific\ndifficulties in the application of his theory, but also by a certain\ninstinctive or temperamental dissatisfaction with such a general\nconclusion as the one I have indicated; and many able naturalists feel\nthe same difficulty to-day. Whether this be justified or not, it is\nundoubtedly the fact that few working naturalists feel convinced that\nthe problem of organic evolution has been fully solved. One of the\nquestions with which research is seriously engaged is whether\nvariations or mutations are indeterminate, as Darwin on the whole\nbelieved, or whether they may be in greater or less degree\ndeterminate, proceeding along definite lines as if impelled by a _vis\na tergo_. The theory of \"orthogenesis,\" proposed by Naegeli and Eimer,\nmakes the latter assumption; and it has found a considerable number of\nadherents among recent biological investigators, including some of our\nown colleagues, who have made important contributions to the\ninvestigation of this fundamental question. It is too soon to venture\na prediction as to the ultimate result. That evolution has been\northogenetic in the case of certain groups, seems to be well\nestablished, but many difficulties stand in the way of its acceptance\nas a general principle of explanation. The uncertainty that still\nhangs over this question and that of the heredity of acquired\ncharacters bears witness to the unsettled state of opinion regarding\nthe whole problem, and to the inadequacy of the attempts thus far made\nto find its consistent and adequate solution.\n\nHere, too, accordingly, we find ourselves confronted with wide gaps in\nour knowledge which open the way to vitalistic or transcendental\ntheories of development. I think we should resist the temptation to\nseek such refuge. It is more than probable that there are factors of\nevolution still unknown. We can but seek for them. Nothing is more\ncertain than that life and the evolution of life are natural\nphenomena. We must approach them, and as far as I can see must attempt\nto analyze them, by the same methods that are employed in the study of\nother natural phenomena. The student of nature can do no more than\nstrive towards the truth. When he does not find the whole truth there\nis but one gospel for his salvation--still to strive towards the\ntruth. He knows that each forward step on the highway of discovery\nwill bring to view a new horizon of regions still unknown. It will be\nan ill day for science when it can find no more fields to conquer. And\nso, if you ask whether I look to a day when we shall know the whole\ntruth in regard to organic mechanism and organic evolution, I answer:\nNo! But let us go forward.\n\n\n\n\nCOLUMBIA UNIVERSITY PRESS\n\n\n   A Series of twenty-two lectures descriptive in untechnical\n   language of the achievements in Science, Philosophy and Art, and\n   indicating the present status of these subjects as concepts of\n   human knowledge, are being delivered at Columbia University,\n   during the academic year 1907-1908, by various professors chosen\n   to represent the several departments of instruction.\n\n   MATHEMATICS, by Cassius Jackson Keyser, _Adrain Professor of\n   Mathematics_.\n\n   PHYSICS, by Ernest Fox Nichols, _Professor of Experimental\n   Physics_.\n\n   CHEMISTRY, by Charles F. Chandler, _Professor of Chemistry_.\n\n   ASTRONOMY, by Harold Jacoby, _Rutherfurd Professor of Astronomy_.\n\n   GEOLOGY, by James Furman Kemp. _Professor of Geology_.\n\n   BIOLOGY, by Edmund B. Wilson, _Professor of Zoology_.\n\n   PHYSIOLOGY, by Frederic S. Lee, _Professor of Physiology_.\n\n   BOTANY, by Herbert Maule Richards, _Professor of Botany_.\n\n   ZOOLOGY, by Henry E. Crampton, _Professor of Zoology_.\n\n   ANTHROPOLOGY, by Franz Boas. _Professor of Anthropology_.\n\n   ARCHAEOLOGY, by James Rignall Wheeler, _Professor of Greek\n   Archaeology and Art_.\n\n   HISTORY, by James Harvey Robinson, _Professor of History_.\n\n   ECONOMICS, by Henry Rogers Seager, _Professor of Political\n   Economy_.\n\n   POLITICS, by Charles A. Beard, _Adjunct Professor of Politics_.\n\n   JURISPRUDENCE, by Munroe Smith, _Professor of Roman Law and\n   Comparative Jurisprudence_.\n\n   SOCIOLOGY, by Franklin Henry Giddings, _Professor of Sociology_.\n\n   PHILOSOPHY, by Nicholas Murray Butler. _President of the\n   University_.\n\n   PSYCHOLOGY, by Robert S. Woodworth, _Adjunct Professor of\n   Psychology_.\n\n   METAPHYSICS, by Frederick J.E. Woodbridge, _Johnsonian Professor\n   of Philosophy_.\n\n   ETHICS, by John Dewey, _Professor of Philosophy_.\n\n   PHILOLOGY, by A.V.W. Jackson, _Professor of Indo-Iranian\n   Languages_.\n\n   LITERATURE, by Harry Thurston Peck, _Anthon Professor of the\n   Latin Language and Literature_.\n\n\n   These lectures are published by the Columbia University Press\n   separately in pamphlet form, at the uniform price of twenty-five\n   cents, by mail twenty-eight cents. Orders will be taken for the\n   separate pamphlets, or for the whole series.\n\n  Address\n  THE COLUMBIA UNIVERSITY PRESS\n  Columbia University, New York\n\n       *       *       *       *       *","title":"Biology : $b A lecture delivered at Columbia University in the series on Science, Philosophy and Art November 20, 1907","tradition":"philosophy-ethics","translated_text":null,"word_count":6776}