{"collection":"philosophy-ethics","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_34603/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_34603","id":"gutenberg_34603","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/34603","summary":null,"tags":["Category: Environmental Issues","Category: Health & Medicine","Category: History - Modern (1750+)","Category: Philosophy & Ethics","Category: Science - Biology","Epidemics","Germ theory of disease"],"text":"Produced by Bryan Ness, Keith Edkins and the Online\nDistributed Proofreading Team at http://www.pgdp.net (This\nfile was produced from images generously made available\nby The Internet Archive/American Libraries.)\n\n\n\n\n\nTranscriber's note: A few typographical errors have been corrected: they\nare listed at the end of the text.\n\n       *       *       *       *       *\n\n\nPage numbers enclosed by curly braces (example: {25}) have been\nincorporated to facilitate the use of the Table of Contents.\n\n       *       *       *       *       *\n\n\nEPIDEMICS\n\nEXAMINED AND EXPLAINED:\n\nOR,\n\nLIVING GERMS\n\nPROVED BY ANALOGY TO BE\n\nA SOURCE OF DISEASE.\n\nBY\n\nJOHN GROVE, M.R.C.S.L.\n\nAUTHOR OF \"SULPHUR AS A REMEDY IN EPIDEMIC CHOLERA.\"\n\nLONDON:\n\nJAMES RIDGWAY, PICCADILLY.\n\nMDCCCL.\n\n       *       *       *       *       *\n\n\n    \"The tendencies of the mind, the turn of thought of whole ages, have\n    frequently depended on prevailing diseases; for nothing exercises a\n    more potent influence over man, either in disposing him to calmness and\n    submission, or in kindling in him the wildest passions, than the\n    proximity of inevitable and universal danger.\"--_Hecker's Epidemics of\n    the Middle Ages._\n\n    \"The grand field of investigation lies immediately before us; we are\n    trampling every hour upon things which to the ignorant seem nothing but\n    dirt, but to the curious are precious as gold.\"--_Sewell on the\n    Cultivation of the Intellect._\n\n       *       *       *       *       *\n\n\nTO\n\nBENJAMIN GUY BABINGTON, F.R.S., M.D.,\n\nPHYSICIAN TO GUY'S HOSPITAL,\n\nAND\n\nPRESIDENT OF THE EPIDEMIOLOGICAL SOCIETY,\n\nETC. ETC.\n\nTHESE PAGES ARE, BY HIS KIND PERMISSION,\n\nRespectfully Dedicated,\n\nBY HIS OBLIGED AND FAITHFUL SERVANT,\n\nTHE AUTHOR.\n\n       *       *       *       *       *\n\n\n{v}\n\nPREFACE.\n\nThe following pages have been written with a view to render some aid in\nestablishing a sound and firm basis for future research, on that absorbing\ntopic, the Causes and Nature of Epidemic Diseases.\n\nThe amount of information already published on Fevers, on the Exanthemata,\nand on the Plague, is truly astonishing, and the more so when it is\nconsidered, that at present no rational account or explanation is given of\nthe causes of these affections.\n\nIt appears to me but reasonable to suppose that as every thing on this\nearth has been created on a wise and unerring principle, Epidemic and\nInfectious Diseases are only indicative of some serious errors in our\nsocial arrangements and habits. The dangers and misery brought upon us by\ndisease, may, as shewn by Dr. Spurzheim and Mr. Combe, be warnings against\nthe infringement of the natural laws.\n\nIndeed, what is more rational than to suppose that the Seeds of Disease are\ncoeval with the fall of man. His first disobedience {vi} brought\ndeath:--that his subsequent errors should hasten its approaches is not to\nbe marvelled at. The undetected murderer, though he may escape the\npunishment human justice would inflict upon him for his delinquency,\nsuffers a penalty in the tortures of conscience, infinitely more horrifying\nthan the most ignominious death. The law of nature is triumphant.\n\nNo less certain, though after a different manner, are the consequences of\nminor forms of disobedience. It is so ordained, that certain diseases shall\narise, under peculiar conditions, which may have been brought about by a\ntrain of causes, easily imagined, and difficult to be explained, but all\nhaving their origin in the vices and errors of man in his moral and social\nrelations.\n\nIf man neglects the cultivation of the ground; with rank vegetation, the\ngerms of fever will invisibly grow and multiply; if he harbours that which\nis rotten and corrupt, he is himself consumed by those agents destined to\nremove the rottenness and corruption; it is a part of the law of nature\nthat there should be active and energetic agents for this purpose. The\nseeds of disease, like the seeds of plants, may be shewn to have {vii}\ntheir indigenous localities; like them they may be spread and multiplied;\nlike them they may lie dormant, and after awhile spring as it were into\nactive existence; like them, when the soil and other conditions favour,\nthey are ever ready to make their appearance. And this is the law, the\ngerms of all disease exist, and have existed. Despise the dictates of\nnature, be careless of yourself and those around you, neglect to use the\nmeans which a noble intelligence has placed at your command, and above all,\ntransgress the laws of God, then will disease pursue and attend you, as the\nconscience of the murderer pursues and attends him until he is finally cut\noff.\n\nHis wants and necessities, his sufferings and privations, are the basis of\nthe intellectual progress of man. The wonders of Omnipotence are revealed\nthrough the whirlwind, the storm, the pestilence, and the famine.\n\nThe constructive and perceptive faculties of man have been developed by the\nnecessity of protecting himself from injury by winds and rains; his\nintellectual faculties have been cultivated, by the sufferings of disease\nhaving led him to the study of {viii} organization and life, to discover\nthe cause,--and to chemistry, and other sciences for the cure of his\nailments.\n\nFamine and distress have aroused his emotions, and softened down his\nasperities, so that what appears at first to be the infliction of a Curse\nwithout Pity, is in reality a Judgment with Mercy.\n\nIt occurred to me, that on the formation of the Epidemiological Society,\nthe first question for consideration should be, What is the nature of those\nagents, which induce Epidemic Diseases? are they composed of animate or\ninanimate matter? In other words, do the manifestations of these diseases\nexhibit the operations of living or of chemical forces.\n\nHaving, in my study, dwelt on the subject with an earnest desire to find\nthe truth, I put the suggestion, with my ideas, before the public to reject\nor receive them. If they be rejected, I can but think a full discussion of\nthe enquiry will lead to the most important results. If they be received\nwith favour, I doubt not others, with more ability, will take up the strain\nand resolve the discords into harmony.\n\n  J. G.\n\n  _Wandsworth, September, 1850._\n\n{ix}\n\nCONTENTS.\n\n                                                                   PAGE\n  INTRODUCTION                                                        1\n\n  CHAPTER I.\n\n  IS IT PROBABLE THAT EPIDEMIC, ENDEMIC, AND INFECTIOUS\n  DISEASES, DEPEND UPON VITAL GERMS\n  FOR THEIR MANIFESTATIONS?                                          11\n\n  CHAPTER II.\n\n  THE NUMBER AND VALUE OF FACTS TO SUPPORT\n  THE PROPOSITION.\n\n  SECTION I.--On Reproduction                                        22\n\n  SECTION II.--Historical Notice of Epidemic Diseases                34\n\n  SECTION III.--The Dispersion of Plants and Diseases                64\n\n  SECTION IV.--The Relation between Epidemic and Endemic\n  Diseases                                                           96\n\n  CHAPTER III.\n\n  THE REASONABLENESS OF THE APPLICATION OF\n  THE FACTS TO THE INFERENCE.\n\n  SECTION I.--The Chemical Theory of Epidemics untenable            108\n\n  SECTION II.--The Animalcular Theory of Epidemics untenable        128\n\n  SECTION III.--Sketch of the Physiology and Pathology of\n  Plants and Animals                                                138\n\n  CHAPTER IV.\n\n  RESULTS IN PROOF OF THE TENABLENESS OF THE\n  PROPOSITION.\n\n  SECTION I.--Observations on some of the Laws of Epidemic\n  Diseases                                                          155\n\n  SECTION II.--What is the nature of those Poisons which most\n  resemble the Morbid Poisons in their effects on the body?         166\n\n  SECTION III.--What results do we obtain from the effects of\n  remedial agents, in proof of the hypothesis?                      176\n\n  CONCLUSION                                                        189\n\n       *       *       *       *       *\n\n\n{1}\n\nINTRODUCTION.\n\nIt is one thing for a man to convince himself, but a very different thing\nto be able to convince others.\n\nI am not now speaking of a conviction arising from the impression made by a\nfew startling facts, nor of one forced on the mind by early prejudices, or\nby the dogmas of the schools, but of a conviction arising from careful\nenquiry.\n\nIn the course of that enquiry, the collector of facts, sees their relations\nto the idea in his mind, in a multiplicity of ways, from their remaining,\neach, as one succeeds the other, an appreciable time on the sensorium, and\nundergoing a certain process of comparison and relation, with all other\nfacts and ideas which have been previously stored up. As the materials for\nan edifice which have been shaped and prepared in accordance with the\ncompletion of the design, so do the facts and ideas which are accumulated\n{2} in the mind, become shaped and prepared for the elimination of a truth.\nThe ultimate design of the architect can no more be conceived by the\nexamination of the framework of a window, or the capital of a column, than\nthe whole truth of a proposition by the examination of separate facts; the\nwhole must be conceived and all the relations of all the parts thoroughly\nunderstood, before the architect can be comprehended or the harmony of his\ndesign appreciated.\n\nThe process of thought in the minds of the architect, and in the framer of\na proposition, is never exactly the same as in those who contemplate and\nexamine their completed works. Much may be done, however, by both to aid\nothers in comprehending them. The more accurately they keep in view the\ncourse their minds have taken, the more readily will their descriptions be\nunderstood.\n\nTo simplify the elements of our knowledge is to give others a ready access\nto our thoughts.\n\nTo arrange the course of our ideas in harmony with the elements of our\nknowledge should be the end of all writing, as it is the only means of\nmultiplying knowledge. {3}\n\nIt is not the mere accumulation of facts which constitutes science, any\nmore than a collection of building materials constitutes a house, it is the\narrangement and adaptation of the means to the end by which the house\nbecomes built and science cultivated.\n\nThese reflections have been suggested by the circumstance that for the last\n3000 years and upwards, Pestilences have at certain intervals done their\nwork of destruction, and opened the springs of misery to untold millions,\nand yet I see not that we are much further advanced as to the knowledge of\nthe cause of these inflictions than the Jews in the time of Moses. In the\nLevitical law, as I shall have occasion more particularly to shew\nhereafter, were directions specially given in reference to the plague of\nleprosy; what means should be adopted for the cure of the disease, and for\npreventing its extension, and moreover pointing very significantly to\ncertain facts having connexion with the cause of the affection. Since that\ntime historians generally, and medical writers in particular, have\ndiligently recorded their observations and accumulated facts, on the\nvarious desolating plagues which {4} have afflicted mankind. Some of these\nmen have grappled with the whole subject, and endeavoured to shew the\npresumed relation of the supposed causes in all their intricacies, but it\nis hardly necessary to say that all have signally failed in their attempts\nto furnish us with any practical information.\n\nSatisfied in my own mind that the whole subject is beyond the labour of one\nman, and impressed with the belief that the basis of the enquiry is in\nanything but a satisfactory state, I have applied myself entirely to the\nstudy of the groundwork only, as the primary proceeding for a solid\nsuperstructure.\n\nThe days are past, when imaginary spirits, ethers, and astronomical\nphenomena, were believed to have any essential influence over our destinies\nin a physical point of view; we have therefore to deal with _matter_ in\nsome form or other.\n\nThe question, therefore, which I have proposed for enquiry, is, whether the\nmatter which causes epidemic and endemic diseases, exhibits the properties\nof inorganic or organized matter.\n\nThe properties and qualities of organized {5} bodies, as well as those of\ninorganic matter, need but be stated, and in some instances we may picture\nto ourselves the object, without having seen it, and not be very far from a\ntrue conception. But for this purpose a clear and definite idea must be\npreviously formed, and have taken possession of the mind, of the great\ngeneral divisions of objects in the material world.\n\nHaving made these preliminary remarks, I have suggested a certain mode of\nprocedure in making enquiries of this kind, not perhaps in strict\naccordance with logical systems, but on the principle of nature's\noperations in our own minds, which appears to me, when reduced to a\nsystematic and simple form, to be sufficiently clear and strict for\nsynthetical application, and so concise as to be usefully and practicably\napplied.\n\nIn endeavouring to establish a theory for the explanation of extraordinary\nphenomena, there are certain rules which should guide us in the thorny and\ntreacherous path of speculation. But these rules readily flow from the\ntrain of thought, and if we examine our own minds during their operations,\nwe {6} shall find that the following is the course of our instinctive\nreflections. It is a course we adopt as the test of theories when formed,\nand is a guide in all cases for their construction.\n\nWe first commence with an idea, which exists in our minds in the form of a\nproposition: then the following rules naturally suggest themselves:--\n\n1. The probability of the value of our proposition from inference.\n\n2. The number and value of facts to support the proposition.\n\n3. The reasonableness of the application of the facts to the inference.\n\n4. What amount of information in the form of results can be produced in\nproof of the tenableness of the proposition.[1]\n\nIn illustration of the value of these rules the history of Dr. Jenner's\ndiscovery affords an appropriate example. To use the words of Dr. Gregory,\n\"he appears very early in {7} life to have had his attention fixed by a\npopular notion among the peasantry of Gloucestershire, of the existence of\nan affection in the cow, supposed to afford security against the Small Pox;\nbut he was not successful in convincing his professional brethren of the\nimportance of the _idea_.\"\n\nThe popular notion of the peasantry originated the idea in Jenner's mind,\nand it became fixed there as a proposition.\n\n1. He commenced his enquiry by observing that the hands of milkers on the\ndairy farms were subject to an eruption, and he _inferred_ that the notion\nof the peasantry bore the stamp of probability, which strengthened the idea\nin his mind and gave force to the proposition.\n\n2. His next step was to accumulate facts; he found on enquiry that the\npersons engaged on these farms in milking, possessed an immunity from Small\nPox to an extent sufficient to strengthen the value of his proposition.\n\n3. The reasonableness of the application of the facts to the inference is\nclear from the coincidence that the eruption on the hands of the dairy\npeople bore a striking {8} resemblance to the Small Pox, and as this\ndisease does not usually occur twice in the same individual, the inference\nwas most reasonable that this eruption protected the people from Small Pox.\n\n4. We have but to take the almost universal adoption of vaccination, and\nits acknowledged prophylactic powers against the propagation of Small Pox\nto shew the application of our fourth rule.[2]\n\nBetween the conception of the idea and the accomplishment of Jenner's\ndesigns, vaccination seems to have undergone an incubation of nearly twenty\nyears. During that period, with an energy and perseverance only to be\nobtained by confidence, did this great man brood over and elaborate his\nidea; and well might the 14th day of May, {9} 1796, be styled the birth day\nof vaccination, for on that day was a child first inoculated from the hands\nof a milker.\n\nIn adopting the above method I have endeavoured to bear in mind M.\nQuetelet's observations on the requirements necessary for medical\nauthorship; he says, \"All reasonable men will, I think, agree on this\npoint, that we must inform ourselves by observation, collect well-recorded\nfacts, render them rigorously comparable, before seeking to discuss them\nwith a view of declaring their relations, and methodically proceeding to\nthe appreciation of causes.\"\n\n       *       *       *       *       *\n\n\n{10}\n\n{11}\n\nCHAPTER I.\n\nIS IT PROBABLE THAT EPIDEMIC, ENDEMIC, AND INFECTIOUS DISEASES, DEPEND UPON\nVITAL GERMS FOR THEIR MANIFESTATIONS?\n\nIt is, I believe, almost universally considered that Epidemic, Endemic, and\nInfectious diseases, originate from some imaginary poisons of a specific\nnature, each disease having its own peculiar poison. That this conception\nshould have taken possession of the minds of men, is most natural from the\nsymptoms which characterize these diseases, but when we come to enquire\ninto the nature of these agents, or supposed poisons, we are at once struck\nwith the idea that they exhibit one peculiarity which separates them in a\nmarked manner, from those poisons with which we are familiar; for the\npoisons of Small Pox, Measles, Scarlet Fever, Hooping Cough, Fever, &c.\npossess the power of multiplication, or spontaneous increase, a property\nwhich attaches only to the organic kingdom, and is never known in the\ninorganic kingdom. The source of most of the poisons is to be found among\nmineral or vegetable products. A mineral in combination with an acid or\noxygen may become a poison, and {12} nitrogen in various combinations with\noxygen, hydrogen, and carbon, or with carbon alone, may become a poison;\nthese combinations are, however, in most instances the products of\nvegetable life, others again are obtained from the animal kingdom, such as\nthe poison of the serpent, &c. but in all of these instances, there is not\none in which the power of self-multiplication is to be found.\n\nWe are, therefore, constrained to admit that this feature, which\ndistinguishes poisons, is one well worthy attentive consideration. The\nvarieties of poisons may be classified into those which act topically as\nescharotic poisons, those which act chemically on the blood, and those\nwhose effects are manifested in inducing a speedy annihilation of organic\nor vital action, as in the case of hydrocyanic acid, which is supposed\nspecifically to affect the nervous centres from which originate the vital\nmanifestations. It is rather remarkable that the vital poisons (as I will\ncall them for distinction), seem to have their appropriate locality in the\nblood, they do not primarily affect one organ more than another, all the\neffects we witness resulting from them are to be traced progressively from\nthe blood to other parts of the body. When a person is inoculated with\nsmall pox, a very minute portion (indeed it is impossible to say how minute\nit may be) is sufficient, when absorbed, to excite a certain train of\nsymptoms, all due to absorption of the materies of the disease, and the\nprocess by which {13} that materies arrives at maturity, is that known in\nthe vegetable world as the fructification; this process of fructification\nis a process of development and increase.\n\nI here may repeat that among all the poisons known, constituted as they are\nof various combinations of elementary matter, they are without exception\ndestitute of the power of development or increase. Now, it is pretty\naccurately known what amount of these poisons is necessary to produce their\neffects on the living body; we can say how many drops are sufficient of\nhydrocyanic acid of Scheeles strength, to destroy a man instantaneously.\nAgain, how many grains of arsenious acid are sufficient to induce such an\ninflammatory condition of the stomach and intestine as will end in death,\nand how many grains of morphia, will bring about a fatal coma,--but who\nshall say the amount of the vital poisons necessary to produce their\nresults? It far exceeds the limit of conjecture, to what extent the\ndilution of miasmatic or contagious matter may be carried, and the poison\nyet be capable of committing in a short time the most frightful ravages.\n\nWe may fairly then infer, that if a quantity of matter inappreciable in\namount be sufficient to exhibit the characters of growth and increase, that\nit is endowed with the properties of vitality. That the poisons of scarlet\nfever, of measles, and of small-pox have this power of growth and increase,\nis as much a matter of universal belief as that \"the sun {14} will rise and\nset to-morrow, and that all living beings will die.\"\n\nThis power of individual increase, or reproduction, is the very summit of\nvital manifestation; indeed Coleridge, in his Theory of Life, (in which he\nsays, \"I define life as the _principle of individuation_, or the power\nwhich unites a given _all_ into a whole that is presupposed by all its\nparts,\") places reproduction in the first rank, and expresses his\nhypothesis thus: \"the constituent forces of life in the human living body\nare, first, the power of length or reproduction; 2nd, the power of surface,\nor irritability; 3rd, the power of depth, or sensibility--life itself is\nneither of these separately, but the copula of all three.\"\n\nExtensive research is not required to shew that many thinking men believe\nin the existence of living organic beings, as the elements of contagious\nand epidemic diseases; the idea indeed seems to flow spontaneously in that\ndirection. Whenever thought, and enduring contemplation, have been\nconcentrated on the subject, the result appears to have been the same, a\nfirm conviction in each individual mind that a vital force must be in\noperation; or as Schlegel would define it, \"a living reproductive power,\ncapable of and designed to develope and propagate itself.\"--\"Its Maker\noriginally fixed and assigned to it the end towards which all its efforts\nwere ultimately to be directed.\"\n\nReferring further to beings having the property of reproduction and\npropagation, he says, (using {15} the word nature here evidently as the\nvital principle for want of a better term,) \"Nature indeed is not free like\nman, but still is not a piece of dead clockwork. _There is life in\nit._\"--\"Thus we know that even plants sleep, and that they too as much as\nanimals, though after a different sort, have a true impregnation and\npropagation.\"\n\nWhen Schlegel wrote this, how little could he have imagined the intricacy\nof this proceeding among the lower forms of vegetation. It has been shewn\nby Suminski, and verified by many others, that the mode of impregnation,\nand the period at which it occurs in the ferns, do not at all correspond to\nthe general notion on this subject. He has discovered in the early\ndevelopment of the frond of ferns certain cells, which he denominates\nantheridia, or sperm cells; these contain in their cavity a number of\nsubordinate cells, each containing a spermatazoon. At a certain period of\nthe progress of the frond, the parent cells become ruptured and liberate\nthe spermatoza, these move about in a mucilaginous fluid, which bedews the\ninferior surface of the frond, and become the means of impregnating the\ngerm cells, or pistillidia, with which they readily come in contact. Thus\nthe process of impregnation in these plants occurs during the germination,\nor what corresponds to the period of germination in the seeds of exogenous\nand endogenous plants.\n\nI have referred to the discovery of Suminski in {16} this place to recal to\nthe mind the great and incomprehensible wonders of creation, for who could\nconceive it possible or feasible that even for the impregnation of an\ninferior vegetable, animal life should form an indispensable and essential\nappurtenant of the process. Truly may we say with Coleridge, of plants and\ninsects, \"so reciprocally inter-dependent and necessary are they to each\nother, that we can almost as little think of vegetation without insects, as\nof insects without vegetation.\"\n\nI will make but two more quotations on the supposed vital character of the\ngerms of disease. \"That the air and atmosphere of our globe is in the\nhighest degree full of life, I may, I think, take here for granted, and\ngenerally admitted. It is, however, of a mixed kind and quality, combining\nthe refreshing breath of spring with the parching simooms of the desert,\nand where the healthy odours fluctuate in chaotic struggle with the most\ndeadly vapours. What else in general _is the wide-spread and spreading\npestilence_, but a living propagation of foulness, corruption, and death?\nAre not many poisons, _especially animal poisons, in a true sense, living\nforces_?\"--Schlegel.[3]\n\nIt were useless to multiply quotations to shew {17} that the opinions here\nentertained are matters of general belief among thinking men.[4] I will at\nonce then conclude with an observation of Dr. C. J. B. Williams: he puts\nthe question, \"Does the matter of contagion consist of vegetable seeds? Are\ninfectious diseases the results of the operations and invasions of living\nparasites, disturbing in sundry ways the structures and functions of the\nbody, each after its own kind, until the vital powers either fail or\nsucceed in expelling the invading tribes from the system?\"\n\nAnd this expression, the seeds, is an universal expression, it is a\n\"Household Word\" in connexion with disease. That it has obtained this\nposition in the popular vocabulary is alone a proof of the applicability of\nthe term to the thing intended to be {18} signified. Popular notions, as we\nhave seen in the case of Jenner's discovery, are not to be unheeded. An\ninstance occurs to me, it was a popular belief, that in acne punctata, the\nmatter of a sebaceous follicle, was itself, when pressed out, a worm, the\ndark portion which results from the accumulation of dust upon the matter at\nthe mouth of the follicle was supposed to be the head of the maggot, as it\nwas called; subsequent observation, however, has proved that though this\nmatter is not a worm, it contains an animal within its substance, the\nAcarus folliculorum.\n\nThe popular notions found among savage tribes as to the efficacy of certain\nremedies in the cure of disease have been the means of furnishing us with\nsome of our most valuable medicines, indeed it is almost impossible to say\nwhether originally man did not derive his remedies from the herbs and trees\nby an instinctive faculty impelling him, as it does the animals when in a\nstate of liberty and with freedom of range, to seek certain plants as they\navoid others.\n\nIt is well known that animals when indisposed will find out some spot as if\nalmost led to it by a visionary guide where the \"healing plant\" is to be\ndiscovered. I am told that sheep have this faculty, and that they will,\nwhen affected with the rot, feed upon some plant when they can discover it,\nwhich eradicates the disease.\n\nAlmost every one is familiar with the fact that cats and dogs will crop\nherbage and eat it; I have {19} seen them frequently leave the house and\nproceed to the grass in the most business-like manner, partake of some\nquantity, and quietly return.\n\nA close observer of diseased animals might obtain some useful information\nby noticing the plants cropped by them while in that condition. The\nobservations should be made in a variety of districts in consequence of the\nuncertain distribution of some even of the most commonly scattered plants;\nin one year they may be abundant, but in another they may be almost\nentirely absent from the same spot.[5]\n\nWere it only on the fact of reproduction, I would be contented to take my\nstand that the force of life is the indwelling power of pestilential\nmatter. Reproduction is a law of nature, and the law of nature is the law\nof God. And where do we find He prevaricates with us? The more we study His\nlaws the more harmony and perfection we find; what is seeming confusion in\nthe ignorance of to-day, is order in the knowledge of to-morrow. If any one\nignorant of the law which regulates the diffusion of gases were {20} told\nthat a heavier gas would ascend contrary to its specific gravity through\nthe septum in a vessel containing a lighter gas above the heavier, he would\nnaturally doubt your assertion, and say, \"that is contrary to the law of\ngravity;\" but explain to him the principle by which this comes about, and\nthe objects of the law; the order and beauty of the design become manifest.\nBut this is no equivocation, it is evidence there, that subordinate laws\nexist and nothing more. It has never been found that men have gathered\n\"grapes of thorns and figs of thistles,\" nor has it ever been discovered\nthat inanimate matter multiplies itself. The seed of disease \"is within\nitself,\" multiplying and propagating itself; whether it formed a part of\ncreation at the beginning or not, is rather a question to be solved by\ndivines than physicians. When we know, however, the latency of seeds and\neven of entire plants, and that they may be dried and remain so for years\nyet being brought again into conditions adapted to their active existence,\nthey, as it were, revive from their sleep, and renew again their\nreproductive properties: can we wonder if, in the great scheme of nature,\nexistences new to mankind should make their appearance? When the New\nZealander saw the surface of his ground producing to him unknown plants,\nand the skins of his children generating peculiar eruptions, and each\npropagating its kind, would he look, think you, to the wood or the stones,\nthe air or the water,--for the solution of the {21} mystery? No, he would\nnaturally say these people brought the _seeds_ with them. From the property\nof reproduction possessed by these forms of matter, we infer the value of\nthe proposition.\n\n       *       *       *       *       *\n\n\n{22}\n\nCHAPTER II.\n\nTHE NUMBER AND VALUE OF FACTS TO SUPPORT THE PROPOSITION.\n\n--------\n\nSECTION I.\n\nON REPRODUCTION.\n\nIt is inferred that the proposition, \"_the matter which operates in the\nproduction of Epidemic, Endemic, and Infectious Diseases, possesses the\nproperty of vitality_,\" we proceed now to the enumeration of those facts\nwhich further elucidate this subject.\n\nThe facts must necessarily be such as illustrate the identity of properties\nin the imaginary germs, that are known to exist in demonstrable germs: we\ntake therefore the law of reproduction to be to life, what the law of\nattraction is to gravitation.[6]\n\n{23}\n\nBut further; do those matters which engender disease furnish to our minds\nthe properties inseparable from life in the abstract? Though the faculty of\nreproduction is essentially an evidence that the thing which reproduces its\nkind must be a living body, yet it is only a property or power of living\nbeings and is not itself life, it therefore is necessary to establish the\nfact that the _materies morbi_ not only has the power of reproduction, but\nalso those properties which in the abstract will prove as far as\ndemonstration can go, that it has the essential properties common to all\nliving bodies.\n\nI must again quote from Coleridge, he says: \"By life I every where mean the\ntrue idea of life, or that most general form under which life manifests\nitself to us, which includes all its other forms. This I have stated to be\nthe _tendency to individuation_ and the degrees or intensities of life, to\nconsist in the progressive realization of this tendency. The {24} power\nwhich is acknowledged to exist wherever the realization is found, must\nsubsist wherever the tendency is manifested. The power which comes forth\nand stirs abroad in the bird, must be latent in the egg.\"\n\nThe tendency to individuation cannot be more strongly marked than in the\nsimple experiment of vaccination: we insert a small particle of the\nso-called vaccine lymph under the skin, and by this means we multiply to an\nenormous extent, the power which, in the first instance, we had in the form\nof minute corpuscles in a dry and apparently inert state; nevertheless,\nthough in this condition there must have existed the tendency to\nindividuation or multiplication of individual existence, and the germs are\nhere to their active existence, as seen in the development of the vaccine\nvesicle, what the egg is to the bird,[7] as described above; we may,\ntherefore, say that the power which exhibits itself in the production of a\nvaccine vesicle, must have been latent in the dried matter. It is the\nopinion of Muller that the entire vital principle of the egg {25} resides\nin the germinal disk alone, and since _the external influences which act on\nthe germs_ of the most different organic beings are the same, we must\nregard the simple germinal disk, consisting of granular amorphous matter,\nas the potential whole of the future animal, endowed with the essential and\nspecific force or principle of the future being, and capable of increasing\nthe very small amount of this specific force and matter, which it already\npossesses, by the assimilation of new matter.\n\nAfter speaking of inanimate objects, Dr. Carpenter says; \"and what compared\nwith the permanence of these is the duration of any structure subject to\nthe conditions of _vitality_? _To be born_, to grow, to arrive at maturity,\nto decline, to die, to decay, is the sum of the history of every being that\nlives; from man, in the pomp of royalty, or the pride of philosophy, to the\ngay and thoughtless insect that glitters for a few hours in the sunbeam and\nis seen no more; from the stately oak, the monarch of the forest through\nsuccessive centuries, to the humble fungus which shoots forth and withers\nin a day.\"\n\nTo be born, signifies the faculty of reproduction existing or having\nexisted in an antecedent being to that one born, and also that itself\npossesses equally a like power. To be born, is the first expression which\nmust be used in speaking of the faculties or properties of living beings as\nindependent existences, the annual formation of buds, trees, and shrubs, is\na multiplication of the species; the coral {26} and various budding polypes\nincrease by this process, indeed what is the seed of a plant, or the egg of\na bird, or the ovum of mammalia, but cast off buds; in all, the new being\nwas originally a portion of its parent, and if we examine the ovary of the\nvegetable, the bird, or the mammal, can we find any expression more fitting\nto designate the process than that of budding. To be born then, is the\nevidence of an act of one living being, and the commencement of a series of\nvital phenomena in another, but all these are subsequent to reproduction,\nand constitute another chain of vital acts, all tending to a similar\nresult, the multiplication of the species.[8]\n\nNow, whether we apply the philosophical language of Coleridge, or the\nlanguage of observation of Muller, in confirmation of the doctrine here\ninculcated, we arrive at the same point.\n\nDo we not witness in the newly formed vaccine vesicle, an increase of the\nspecific force and principle? We certainly have acquired by the process of\nvaccination a manifold multiplication of power, and is there not also\nassimilation of new matter in {27} which this power resides? And does not\nevery particle of this new matter contain within itself the same force and\nprinciple, as existed in that which generated it?\n\n\"We revert again to potentiated length in the power of magnetism\n(reproduction); to surface in the power of electricity, and to the\nsynthesis of both or potentiated depth in constructive, that is chemical\naffinity.\"[9]\n\nSome may be at a loss to conceive, at first, how irritability may be\nconsidered a property of all vegetable matter; that it does exist in some\nvegetables is certain, but that it does exist in all living beings is\nequally certain;[10] the term, however, which would appear more appropriate\nwhen that irritability does not exhibit itself in an appreciable form, is\n_impressibility_. Irritability, as commonly understood, is seen in its\nhighest condition in muscular tissue; but \"the irritable power and an\nanalogon of voluntary motion first dawn on us in the vegetable world in the\nstamina and anthers at the period of {28} impregnation.\"--\"The insect world\nis the exponent of irritability, as the vegetable is of reproduction.\"\n\nThe property of irritability attains its acme in man, the most highly\norganized of all beings; and its gradations pass downwards through the\nwhole scale of animate creation; not so reproduction, for this faculty\nobserves the very opposite direction, for in plants a single impregnation\nis sufficient for the evolution of myriads of detached lives.\n\nReproduction is a fact, it is an essential property of life, and is a\nreality to us from observation; but irritability is not so tangible and\ndemonstrable a property. We nevertheless may assume its universality, from\nthe circumstance that we lose sight of it by imperceptible degrees; the\nirritability of the sensitive plant is as much irritability as that of the\nhighly organized muscle; but because the faculty evades our perception, \"in\ntapering by degrees, becoming beautifully less,\" we have no reason for\npronouncing its total extinction at any one point of the vegetable\nkingdom,[11] any more than we should have {29} in saying that we see the\nend of the earth, when describing the extent of our vision as we stand on\nthe sea shore. The extreme limit of our vision is the tangent of the circle\nin reference to our visual organs; but how many tangential points there may\nbe beyond, it is impossible to say without knowing the dimensions of the\ncircle.\n\nI think we are now in a condition to assume, as far as abstraction will\nconduct us without proceeding to an extreme length, that the _materies\nmorbi_, or, as I will now call them for the sake of clearer distinction,\n_semina morbi_, possess those properties which in the abstract are common\nto all living beings.\n\nAnother argument strikes me as capable of adding further strength to the\nproposition. We need but be told that a small piece of iron was placed in a\ncertain position with regard to another piece of iron, and that the smaller\npiece moved through a given space and became attached to the larger, to\ninfer that magnetic force was in operation. Supposing this magnet then to\nbe folded in paper, and that it {30} be promiscuously placed near a\ncompass, the deflection of the needle would indicate that some object in\nthe vicinity was the cause of the deflection; we may farther try what\npositions the needle takes by varying the position of the packet, and thus\npoint out which is the north and which the south pole of the screw of\npaper. If we may consider attraction then to be to gravitation what\nreproduction is to life, we do not err in saying in the one instance that\nthere is a living being, and in the other there is a magnet.\n\nThe nebular theory, from which some astronomers made the foundation of many\nspeculations, came with so much interest to our minds that the fascination\ncould not be resisted. It was most delightful to revel in the imagination\nthat we possessed a key to the mode of formation of the starry hosts, and\nwhen speculation had taken its extreme limits in the \"Vestiges of the\nNatural History of Creation,\" and the nebulae had served as the ground work\nof a gigantic scheme, Lord Ross's monster telescope swept the heavens of\nits cobwebs. We can imagine this great promoter of science saying to us,\nGentlemen, the clouds which have obscured you, are composed of myriads of\nstars, and comprise systems as vast and as luminous as our own, had you but\npower of vision to discern them. A new light thus appeared to philosophers,\nand though no great practical results may flow from the discovery, it is\ninstructive from the fact that the imperfectly aided or unaided vision,\nshould not limit legitimate {31} inference. The nebulae before Lord Ross's\ndiscovery were to the astronomer what the materies of epidemic and\ninfectious disease are to medical men. In the absence however of a giant\nmicroscope to reveal such great truths, we may yet dimly shadow them by the\nlight of our reason. It was predicted in 1849 that minute vegetable germs,\nin all probability all of the same type, were the agents producing epidemic\nand infectious disease. In 1850, Mr. Oke Spooner says,[12] \"On examining\nthe matter of Small {32} Pox and Cow Pox in every stage, he finds its\nessential character to consist of a number of minute cells not exceeding\nthe 10,000th part of an inch in diameter: being about one-fourth smaller\nthan the globules of the blood, containing within their circumference many\nstill more minute nuclei, and presenting beyond their circumference\nbud-like cells of the same size and character as those contained within the\ncircle.\"\n\nShould these observations made by Mr. Spooner turn out to be correct, they\nwill but fulfil my anticipations. Then again shall we see the same\napplication of imperfect vision to the limitation or temporary obstruction\nof solid and determinate knowledge.\n\nWe may reasonably expect that these bodies, discovered by Mr. Spooner,\nshould be the elementary matters of disease. Their existence was predicted\nfrom the probability that living matter must be the agent; moreover, that\nthis matter when discovered {33} would be cellular, most probably\nresembling the yeast plant as described by Mr. Spooner.\n\nIt was predicted that a planet would be discovered in a certain position in\nthe heavens, because the perturbations of a comet indicated an attracting\nbody in the path of the eccentric wanderer; the prediction and the\nfulfilment were almost simultaneous.\n\n       *       *       *       *       *\n\n{34}\n\nSECTION II.\n\nHISTORICAL NOTICE OF EPIDEMIC DISEASES.\n\nThe earliest notices we have of Pestilences are contained in Holy Writ. The\nplagues which smote the Egyptians in the time of Moses are not unworthy\nsome comment here. Of those ten plagues, four out of the number were due to\nthe miraculous appearance of myriads of the lower animal tribes, in three\ninstances of insects,[13] viz. lice, flies, and locusts; in the fourth,\nwhen Aaron stretched forth his hand with his rod over the streams, over the\nrivers, and the ponds, frogs came up and covered the land of Egypt. In\nthese instances living beings are made the instruments in God's hand for\nthe punishment of the wicked. These plagues include the second, third,\nfourth, and eighth. The first plague is mentioned as a conversion of the\nwaters into blood. Now if we may take this expression as being literal,\nthere is no reason to suppose that this blood differed in any respect from\nordinary sanguineous liquid; we therefore may assume, as the blood is every\nwhere in Scripture spoken of as the _life_, that this fluid was endowed\nwith vital properties.\n\n{35}\n\nThe fifth plague is described as a murrain among beasts; and the sixth, as\nexhibiting itself as \"a boil breaking forth with blains, upon man and upon\nbeast.\"[14] Now these affections bear a resemblance to the diseases known\nto us at the present day through authentic records. The Black Death of the\n14th century affords in its history but too awful a picture of the horrors\nof such pestilences. In the tenth plague, the smiting of the first-born, we\nare not told by what means it was brought about; but we have something even\nhere to lead us to conjecture. In the second visitation of the Black Death,\nthere were destroyed a great many children whom it had formerly spared, and\nbut few women. The seventh plague of hail is within our conception; as is\nalso that of darkness, the ninth plague.\n\nIt is not a little remarkable that of the ten plagues, seven of them\ndepended upon agents intelligible to our comprehension; we can conceive of\n{36} the invasion of a country by myriads of loathsome insects and\nreptiles, and can imagine the wrath of an offended Deity directing the\nforce of a supernatural storm of hail upon a disobedient people; and we can\nconjecture, though faintly, the consternation of human nature on being\nsubjected to a total darkness of three days' duration, when we consider\n_that_ darkness has been described, as \"a darkness that might be felt.\"\n\nFrom this abstract we discover that the three plagues whose causes we\ncannot understand, or rather upon which no light has been thrown by\nScripture, bear analogies to those which we recognise, in the writings of\nmodern authors, as fearful pestilences.\n\nIt is now our province to reflect on the causes supposed to be in operation\nin the three instances, which become naturally separated from the rest.\n\nWe are told that a murrain appeared among the cattle, without any\npreliminary step. When the blains broke out upon man and beast, Moses had\nbeen previously directed by the Almighty to take handfuls of the ashes of\nthe furnace, and sprinkle them towards the heaven in the sight of Pharaoh.\n\"_And it shall become small dust in all the land of Egypt_, and shall be a\nboil breaking forth with blains upon man and upon beast, throughout all the\nland of Egypt.\"\n\nAnother coincidence, in connexion with subsequent pestilences, arrests the\nattention, on the subject of the mysterious appearance on these occasions\nof {37} matter resembling dust being prevalent about the houses, and on the\nclothes of the people. Clouds also, and showers of dust-like particles,\nwere not of infrequent occurrence. Indeed, in the summer of 1849, during\nthe progress of the Cholera, several phenomena of a similar nature were\nobserved and authenticated; I myself can bear testimony to one instance of\nthe kind. It was observed by many persons in my neighbourhood after the\npassage of an ominous and lurid cloud, that as they walked their clothes\nbecame covered with a singular dust-like matter of very peculiar\nappearance. That this phenomenon was not destitute of significance may be\ngathered from the fact, that on the night of that day several severe cases\nof Cholera occurred, though our village had been comparatively free for ten\ndays.\n\nHecker, in writing on the Black Death says, the German accounts expressly\nspeak of a \"thick stinking mist which advanced from the east,[15] and {38}\nspread itself over Italy; there could be no deception in so palpable a\nphenomenon.\" It is not unworthy of mention, that in the East successive\ninvasions of locusts \"which had never perhaps darkened the sun in thicker\nswarms,\" preceded the great outbreak of this disease, for they left famine\nin their train.\n\nFrom 1500 to 1503 in Germany and France, during the prevalence of the\nsweating sickness, spots of different colours made their appearance,\n\"principally red, but also white, yellow, grey, and black, often in a very\nshort time, on the roofs of houses, on clothes, on the veils and\nneckerchiefs of women, &c.\" Blood rain is also mentioned as having occurred\nat this time, which consisted of the aggregation of minute particles of red\nmatter.\n\nIn the seven plagues, miraculous operations of the Deity consisted in the\nunusual manifestation of phenomena, but which in their effects are\nrecognizable as of clear and definite import. The miracles here are,--in\nthe _mode_ of producing the swarms of frogs, locusts, &c. but they are\nmanifest and unmistakeable _causes_ of plague and famine; in the other\nthree, on the contrary, we witness only the effects, the causes are hidden\nfrom us; we may, therefore, as in current events, legitimately investigate\nthe subject, and what better course can be adopted than that which\nclassifies the traditionary past with all subsequent history. Presuming\nsuch a method of research to be admitted, I have assumed that as {39} the\n_causes_ of the seven plagues have been distinctly given, the others,\nthough only mentioned in their effects, were due to causes of a nature in\nsome way to be compared with their concomitants, that is to say, if a\nspecial intervention of the Deity brought about a miraculous appearance of\nfrogs, lice, &c. there is but little reason to doubt that some other agent\nwas miraculously multiplied and concentrated to induce the murrain,\nengender the blain, and smite the first-born: as if to lead us into this\nenquiry, on the visitation of the blain in man and beast, the Bible History\ntells us that Moses threw ashes of the furnace, which became a dust\nthroughout all the land of Egypt; we cannot imagine that this simply as\nashes could have caused the blain, we may conclude that by some special\nmiracle, either the ashes were converted into a specific form of matter\ncapable of inducing the effects recorded, or that an independent septic\nmatter was generated for the purpose. If the latter, the act of throwing\nthe ashes of the furnace into the air may have been intended to signify\nthat the extremely minute division of the particles when thus cast into\nspace, typified the inscrutable and hidden nature of the matter endowed\nwith such marvellous properties.[16]\n\n{40}\n\nFurther on in the book of Leviticus are passages which I cannot forbear\ntranscribing, for they point out to us most indubitably a line of enquiry\nin reference to diseases of a contagious nature.\n\n\"The garment also that the plague of leprosy is in, whether it be a woollen\ngarment, or a linen garment, whether it be in the warp or woof, of linen or\nof woollen, whether in a skin, or in any thing made of skin, and if the\nplague be greenish or reddish in the garment ... it is a plague of leprosy,\nand shall be shewed unto the Priest, and the Priest shall look upon the\nplague and shut up it that hath the plague seven days; and he shall look on\nthe plague on the seventh day; if the plague be spread in the garment,\neither in the warp, &c. ... the plague is a fretting leprosy, it is\nunclean. He shall therefore burn that garment ... wherein the plague is,\nfor it is a fretting leprosy; it shall be burnt in the fire. And if the\nPriest shall look, and behold, the plague be not spread in the garment ...\nthen the Priest shall command that they wash the thing wherein the plague\nis, and he shall shut it up seven days more: and the Priest shall look on\nthe plague, after that it is washed: and behold if the plague have _not_\nchanged his colour, and the plague be not spread, it is unclean; thou {41}\nshalt burn it in the fire; it is fret inward; whether it be bare within or\nwithout. And if the Priest look and behold the plague be somewhat dark\nafter the washing of it, then he shall rend it out of the garment ... and\nif it appear still in the garment either in the warp or the woof ... it is\na spreading plague: thou shalt burn that wherein the plague is with fire.\nAnd the garment ... which thou shalt wash, if the plague be departed from\nthem, then it shall be washed the second time and shall be clean.\"--Chap.\nxiii. 47-58.\n\nAgain in Deuteronomy. The curse for disobedience: \"The Lord shall make the\npestilence cleave to thee until he have consumed thee from off the\nland.--The Lord shall smite thee with a consumption, and with a fever, and\nwith an inflammation, and with an extreme burning, and with the drought,\nand with blasting, and with _mildew_, and they shall pursue thee until thou\nperish.--The Lord shall make the rain of thy land _powder_ and _dust_: from\nheaven shall it come down upon thee until thou be destroyed.\"\n\nIt may be said, and I doubt not will be said, all this is unnecessarily\ndragging the sacred volume into an enquiry totally foreign to its general\ntenor; on the contrary, however, I maintain by that Book we are to learn\nthe ways of God to man, and further, that no study can impress mankind with\nso awful, so terrific an idea of his responsible position, as that which\nleads him into the investigation of the causes {42} by which the Almighty,\ndoubtless in His wisdom, has thought fit at various epochs of this world's\nhistory, to place man face to face with pestilence, famine and sudden\ndeath.\n\nThere is no man would less willingly than myself introduce profanely the\nrevelations of Scripture. The observations here made are not, therefore,\nintended for light or heedless controversy; if they have a significance of\nany import, let them be alluded to in the same spirit with which they have\nbeen quoted; if they convey nothing for approval to the reader, let silence\nrest upon them. To those who would fain disregard my request, let me recall\nto their minds the veneration which from childhood I trust we have always\nfelt on hearing or seeing those two words--Holy Bible.\n\nIt is yet to be determined, whether the greenish or reddish appearance of\nthe garment spoken of, as being contaminated with the plague of the leprosy\nhad any specific relation to the disease itself. The priest orders that the\ngarment shall be shut up seven days, and on the seventh day, if the plague\nbe increased, by which, of course, is meant if the greenish or reddish\ncolour have increased, and from which we may gather that a power of\nspontaneous increase was possessed by the matter, such a result indicated a\nfretting leprosy, and the garment was to be burnt. Again, though there may\nhave been no increase, but a persistence of the coloured matter after\nshutting up and washing the garment, it is to {43} be burnt, for it is fret\ninward, signifying, that the germs of the affection are still there, and\nmay soon increase. Other rules follow in reference to the plague of\nleprosy, and the mode of deciding whether an article be unclean or clean is\ndefinitely laid down, but our purpose is served in mentioning the above, to\nshew that in the time of Moses the spontaneous increase of certain minute\nmultiplying germs was supposed to have a close connexion with disease. It\nis equally clear, that the priests were aware by the order given them, that\nif the ordinary modes of purifying articles of clothing failed in their\neffect, the safest and surest method of destroying infectious matter was to\nresort to the practice of consuming by fire all materials capable of\npropagating an infectious malady.\n\nThe facts above noticed, accurately correspond to what we now know as\napplicable to the matter of infectious and contagious maladies. It is a\nrule, I believe universally adopted throughout the Poor-houses of this\ncountry, to put the clothes of all persons about to become residents in\nthese establishments, into ovens, where they are submitted to a temperature\nincompatible with the existence of either animal or vegetable life. By this\nmeans all living matters are destroyed, but the fabrics and inorganic\nmatters retain their properties intact. This simple proceeding, I am\ncredibly informed, is an effectual preventive of contamination by articles\nof clothing, a desideratum of no small importance, when it is {44}\nremembered that the diseases among the poor owe much of their inveteracy to\nthe accumulation of effete organic matters about their persons and clothes.\n\nA few more observations are called for on the quotation from Deuteronomy,\nin which allusion is made to living matter being an agent in the production\nof disease. In the curse upon the children of Israel for disobedience, we\nread that they are to be smitten with mildew. No further information,\nhowever, is vouchsafed to us, nevertheless, we can conceive the wretched\ncondition of those on whom the curse might fall. Again, we find in a\ncontinuation of this curse that the Almighty uses means such as He adopted\nin the sixth plague of the Egyptians. The ashes of the furnace became a\nsmall dust in all the land of Egypt, breaking forth with blains upon man\nand beast. In the curse of the Israelites the words are: \"The Lord shall\nmake the rain of thy land _powder and dust_: from Heaven shall it come down\nupon thee until thou be destroyed.\"\n\nIt might be conjectured that the absence of rain would be sufficient to\naccount for the extinction of the people on whom the curse was pronounced,\nby the famine and drought necessarily attendant upon the loss of moisture.\nBut this does not appear to be the meaning of the passage, for the powder\nand dust are mentioned as the agents of destruction; besides, in the\ncontinuation of the curse, the locust is to destroy the grain, the worm the\ngrapes, and {45} the olive is to shed his fruit; we may thus take for\ngranted that drought and famine are not to be caused by the showering of\npowder and dust, it must consequently be supposed that the effects of the\ndust in the instance of the Egyptians are to be compared and classified\nwith those of the dust which smote the Israelites.\n\nAs far then as Sacred History conducts us in the enquiry, concerning the\ncauses of pestilences, we gain encouragement in the belief that living\ngerms are the active agents, for in the case of the leprosy, we have\nevidence of reproduction in connexion with infection, which, if our line of\nargument be tenable, amounts to demonstration; then, in the other instances\nof the plagues, by boils and blains, they distinctly bear comparison with\nthe accounts given by profane writers, of the visitations of pestilences on\nthe earth, subsequently to those mentioned in Scripture history.\n\nThis leads now to the consideration of recorded facts observed and noted\nduring the various Epidemics in the early and subsequent periods of Man's\nHistory, as given by those on whom reliance may be fairly placed.\n\nSetting aside the uncertain information contained in the writings of the\nChinese,[17] a people whose {46} progress in the science and practice of\nMedicine has nothing to commend it (even as it is at the present day) to\nthe notice either of the physician or the historian, unless it be to the\nlatter as a mark of peculiarity both in a social and political point of\nview,--passing also over the Egyptians, the Arabians, and the Greeks,--and\neven Hippocrates himself, we are driven to the Romans for any authentic or\nprecise notice of Epidemic Affections. It has been attributed to\nHippocrates that he predicted the appearance of the Plague at Athens, {47}\nand that when it was introduced into Greece he dispelled it, \"by purifying\nthe air with fires into which were thrown sweet-scented herbs and flowers\nalong with other perfumes.\"[18] But little advantage can be derived from\nenquiries concerning the first appearance of any disease, for the\nprobability of discovering the primary cause is certainly a {48} hopeless\ncase, if attempted by means of the writings of ancient authors, when it is\nrecollected that with all the science and learning of the ancient\nEgyptians, the use of optical instruments was not comprised among the\nparaphernalia of their arts. The knowledge that was limited to the powers\nof natural vision, where the foundation of knowledge is based upon facts\nobtained through the aid of that penetrator of nature's secrets, the\nmicroscope, offers no advantages to the student of the present day.\n\nTo say that a disease commenced in the East and travelled westward, and at\nlength found a habitation and a name in every part of the globe, is no more\nthan to say that disease is coeval with the fall of man. The cause is as\nmuch hidden in the region of its birth, as in that where it sojourns for a\ntime. The cause of the sweating sickness was as much a mystery in England\nas in all the other nations of Europe, which were visited by its\ndevastating power. And these observations apply with as much force to one\ndisease as another; for even our indigenous ague, originating in some\nplaces so limited that the shadow of a passing cloud may mark the boundary\nof its dwelling place, as inscrutably evades our vigilance, with all the\nappliances that art can bring to our assistance, in endeavouring to evoke\nits extraordinary properties under the cognizance of our senses.\n\nIf we weigh the air which carries the poison, or analyze it by the most\ndelicate chemical tests, or {49} take the weight of the atmosphere which is\ncharged with it, or if we take the blood which carries the germs of the\ndisease to the tissues of the body, and submit them after the work of\ndestruction is accomplished, to the most rigid inspection, we can but\nexclaim,\n\n \"These are Thy marvellous works!\"\n\nand confess our total inability to fathom the unbounded.\n\nIf then no practical advantage can accrue from investigating the writings\nof the ancients on these subjects, beyond comparing their historical\nstatements with those of more recent date, our purpose will be served by\noccasionally embodying any remarkable observations of the former with those\nof the latter.\n\nIn proceeding with this course it were better to confine our minds chiefly\nto two diseases which appear from history to have been known from the\nearliest periods, these are the Plague and the Small Pox, mentioning other\ndiseases only _en route_.\n\nPassing then, to the sixth century of the Christian era for the first\ndistinct and connected account of the Plague, it appears from a host of\ntestimony, that the history of this disease, as given by Procopius, well\nmerits our attention. Drs. Friend and Hamilton, in their Histories of\nMedicine, and Gibbon, in his History of Rome, are equally warm in their\npraise of Procopius: the latter says, he \"emulated the skill and diligence\nof Thucydides in the {50} description of the Plague at Athens.\" The account\ngiven by Procopius of this disease, does not differ materially from that\ngiven by subsequent eye-witnesses of similar pestilences. Its point of\norigin is clearly marked, and its mode of dispersion in all directions\ndistinctly traced from \"the neighbourhood of Pelusium, between the\nSerbonian bog and the eastern channel of the Nile.\" It commenced in the\nyear 542. It raged in Constantinople in the following year, and it was in\nthis city that our historian gathered the materials which are handed down\nto us. When, however, we anxiously look for any explanation as to the cause\nof the malady, we are told that it must have been a direct visitation from\nHeaven, in consequence of the eccentric characters exhibited in its\nwide-spreading influence, in not yielding to the scrutiny nor bending to\nthe laws known to prevail, and to regulate the course of other diseases:\nneither country nor clime, age nor sex, the strong and healthy, nor the\nweakly and previously diseased, could be said to be free from its\nindiscriminate destruction.\n\nBut some phenomena preceding the outbreak of the pestilence are observed as\ncoincidences by all authors. Gibbon thus writes: \"I shall conclude this\nchapter with the comets, the earthquakes, and the plague which astonished\nor afflicted the age of Justinian.\" From the accounts given by this author,\nearthquakes for some years had been threatening and destroying many\nportions of the globe, {51} that in the ruins of cities and in the chasms\nof the earth, great was the sacrifice of human life. Constantinople, which\nsuffered so severely from the plague is said to have been shaken for forty\ndays. These great disturbances of the globe have been always looked upon as\nindicating other and important influences of a secret or hidden nature;\nthese impressions on the minds of the people are traceable throughout the\nhistories of all epidemics, and have been sufficiently distinct among the\npeople of our own time, preceding and during the period of infliction.\n\nFrom this short notice of the Plague of 543, I pass to the ninth century,\nwhen Rhazes, the Arabian physician, endeavoured to enlighten the world on\nthe subject of Small Pox.[19] In quoting his opinions, I am not to be\nunderstood as subscribing to them, but merely endeavouring to point out\nsome peculiar and interesting observations.\n\nFirst, then, Rhazes attributes the disease to a condition of the blood,\nwhich he thus describes, to shew how it happens that in infancy and\nchildhood the disease is most prevalent, and that old age is {52} least\nliable to the affection.[20] \"The blood of infants and children may be\ncompared to _must_, in which the coction leading to perfect ripeness has\nnot yet begun, nor the movement towards fermentation taken place; the blood\nof young men may be compared to must which has already fermented and made a\nhissing noise, and has thrown out abundant vapours and its superfluous\nparts, like wine which is now still and quiet, and arrived at its full\nstrength, and as to the blood of old men, it may be compared to wine which\nhas now lost its strength, and is beginning to grow vapid and sour.\"\n\n\"Now the Small Pox arises when the blood putrifies and ferments, so that\nthe superfluous vapours are thrown out of it, and it is changed from the\nblood of infants which is like must, into the blood of young men which is\nlike wine perfectly ripened: and the Small Pox itself may be compared to\nthe fermentation and the hissing noise which take place at that time.\"\n\nBut the cause of the disease is simply alluded to by this author, as\ndepending upon \"occult dispositions in the air,\" and as he speaks here of\nMeasles with the Small Pox he goes on to say--\"which necessarily cause\nthese diseases and predispose bodies to them.\" This notion of Rhazes that\nthere is some peculiar condition of the blood which favours a process\nresembling fermentation is not without interest. The circumstance that\nindividuals are not {53} usually liable to a second attack of the disease,\nno doubt directed the attention of this physician to compare the process of\nfermentation with disease of such a nature, seeing that when the whole of\nthe saccharine matter was converted into spirit, the hissing noise, as he\ncalls it, or the disengagement of carbonic acid gas would cease, and the\ncapacity for fermentation be entirely gone. So that the occult conditions\nof the air, their power of inducing a disease, and multiplying the matter\ncapable of engendering a similar affection, stood in the mind of Rhazes as\nanalogous if not identical phenomena.\n\nWe pass now without further comment to the epidemics of the Middle Ages;\nand here the work of the philosophical Hecker leaves us little else to\ndesire in the way of information, as far as it is obtainable from published\nrecords. From the manner in which he has grouped the facts which presented\nthemselves to his mind in the course of a most laborious research, he has\nsaved the student of this subject much toil in acquiring matter for\nreflection; he has here but to read and digest.\n\nI know not how to select from this invaluable work the most striking\npassages, to strengthen and support my hypothesis, for not a page is\ndestitute of facts corroborative of the doctrine that vital germs are the\nmaterial agents of pestilential disorders. The opening paragraph to the\nBlack Death is a most cogent illustration of the assertion; it is, as it\nwere, the theme of the work. \"That {54} Omnipotence, which has called the\nworld with all _its living creatures into one animated being_, especially\nreveals himself in the desolation of great pestilences. The powers of\ncreation come into violent collision; the sultry dryness of the atmosphere;\nthe subterranean thunders; the mist of overflowing waters are the\nharbingers of destruction. Nature is not satisfied with the ordinary\nalternations of life and death, and the destroying angel waves over man and\nbeast his flaming sword.\"\n\nI must here apologise for large transcripts from Hecker's work, for neither\ncould I command the amount of knowledge there displayed, nor use such\nappropriate language as the learned translator has employed.\n\nIt is not doubted that the Black Death was an Oriental plague, only of more\nthan usual severity, and wider spread influence of the infectious nature of\nthis disease, and the active properties of the matter producing it. Hecker\nsays, \"articles of this kind--bedding and clothes--removed from the access\nof air, not only retain the matter of contagion for an indefinite period,\n_but also increase its activity, and engender it like a living being_,\nfrightful ill consequences followed for many years after the first fury of\nthe pestilence was past.\"[21]\n\n{55}\n\nAs extraordinary atmospheric and telluric phenomena preceded the Plague in\nthe time of Justinian, so do we find similar instances recorded as the\nprecursor of a similar visitation 700 years later. I am concerned more with\nthose circumstances which refer more especially to my subject, _viz._ the\ndevelopment of organic matter, and the peculiar odours of the atmosphere,\nthe latter being evidence of some foreign and unusual production in our\nrespiratory media. \"On the island of Cyprus, before the earthquake, a\npestiferous wind spread so poisonous an odour, that many being overpowered\nby it, fell down suddenly and expired in dreadful agonies. A thick stinking\nmist advanced from the east, and spread itself over Italy.\"\n\n{56}\n\nIt is probable that the atmosphere contained foreign and sensibly\nperceptible admixtures to a great extent, which, at least in the lower\nregions, could not be decomposed or rendered ineffective by separation. In\n1348 an unexampled earthquake shook Greece, Italy, and the neighbouring\ncountries. During this earthquake the wine in the casks became turbid, a\nproof that changes causing a decomposition of the atmosphere had taken\nplace. \"The insect tribe was wonderfully called into life, as if animated\nbeings were destined to complete the destruction which astral and telluric\npowers had began.\"\n\n\"The corruption of the atmosphere came from the east, but the disease\nitself came not upon the wings of the wind, but was only excited and\nincreased by the atmosphere where it had previously existed.\"\n\n\"The most powerful of all the springs of the disease was contagion; for in\nthe most distant countries, which had scarcely yet heard the echo of the\nfirst concussion, the people fell a sacrifice to organic poison, the\nuntimely offspring of vital energies thrown into violent commotion.\"\n\n\"After the cessation of the Black Plague, a greater fecundity in women was\nevery where remarkable, a grand phenomena, which from its occurrence after\nevery destructive pestilence, proves to conviction the prevalence of a\nhigher power in the direction of general organic life.\" {57}\n\nIn the article Contagion, of the Essay, Sweating Sickness: \"Most fevers\nwhich are produced by general causes, propagate themselves for a time\nspontaneously.\" \"The exhalations of the affected become the germs of a\nsimilar decomposition in those bodies which receive them, and produce in\nthese a like attack upon the internal organs, _and thus a merely morbid\nphenomenon of life, shows that it possesses the fundamental property of all\nlife, that of propagating itself in an appropriate soil. On this point\nthere is no doubt, the phenomena which prove it have been observed from\ntime immemorial, in an endless variety of circumstances, but always with a\nuniform manifestation of a fundamental law._\"\n\nMead, in his Essay on the Plague, makes many observations of great interest\nand worthy a physician of eminence; and where, in recent times, shall we\nlook for any more definite information concerning the causes of\npestilences? It is not a little singular that at the time this book was\npublished, it was read with such avidity that it went through seven\neditions in one year.[22] From this circumstance we may gather that the\npublic generally took a lively and proper interest in a subject that was\nnot only of domestic, but national importance. Whether this interest was\nstimulated by the fact that the work was written expressly by order of the\n{58} government, it is now impossible to say, at any rate much credit is\ndue to the Lords of the Regency for having placed so important a duty upon\none so thoroughly and in every way so duly qualified for the task as Dr.\nMead. It had been well if some of the advice given at that time, as means\nof protection against the Plague, had been applied and put in force during\nthe late visitation of epidemic Cholera, for, however the minds of some may\nbe convinced of the non-contagiousness of Cholera, there are many who hold\na different opinion, and all will acknowledge, that if not strictly a\ncontagious affection, it is clearly proved to be capable of being carried\nfrom place to place, or to use Dr. Copland's words, it is \"a portable\ndisease.\" But this is not the place to discuss the subject of contagion,\nallusion will be made to it hereafter. To return, Mead's expressions are\nsingularly illustrative of the vital power possessed by the germs of\ndisease; he says, \"There are instances of the distemper's being stopt by\nthe winter cold, and yet the seeds of it not destroyed, but only kept\nunactive, _till the warmth of the following spring has given them new life\nand force_. His confession as to the hidden cause of the disease, is worthy\ntranscribing: \"We are acquainted too little with the laws, by which the\nsmall parts of matter act upon each other, to be able precisely to\ndetermine the qualities requisite to change animal juices into such\nacrimonious humours, or to explain {59} how all the distinguishing symptoms\nattending the disease are produced.\"[23]\n\nOn the spread of the Plague is the following:--\"The plague is a _real\npoison_, which being bred in the southern parts of the world, maintains\nitself there by circulating from infected persons to goods, that when the\nconstitution of the air happens to favour infection, it rages with great\nviolence.\" Contagious matter is lodged in goods of a loose and soft\ntexture, which being packed up, and carried into other countries, let out,\nwhen opened, the imprisoned seeds of contagion, and produce the disease\nwhenever the air is disposed to give them force, \"otherwise they may be\ndispersed without any considerable ill effects.\" Gibbon thus speaks of the\nabove quoted work: \"I have read with pleasure Mead's short but elegant\nTreatise concerning Pestilential Disorders;\" many also might read it at the\npresent day with infinite advantage. Mead most satisfactorily combats the\nopinions of the French physicians who maintained the non-contagiousness of\nthe Plague. Experience proves beyond doubt, that certain conditions of\natmosphere, of {60} which we are ignorant, favour the growth and increase\nof pestilences as they do of all vegetation.\n\nDr. Bancroft was of opinion that specific contagions are each and severally\ncreatures of Divine Wisdom, as distinctly and designedly exerted for their\nproduction, as it was to create the several species of animals and\nvegetables around us.\n\nThe indigenous fever of Ireland, which has several times shewn itself in an\nepidemic form, appears to have been as fatal, as the Plague in the South of\nEurope. Its devastations have generally been associated or preceded by\nfamine and general distress. Dr. Harty, writing in 1820, says that thrice\nwithin the last eighty years has the same fever appeared in its epidemic\ncharacter. In the year 1741 Ireland lost 80,000 of her inhabitants from\nthis cause. It is a maculated typhus, and considered to be a special\nproduct of the Emerald Isle. It has been shewn that fever began to exceed\nits ordinary rate in those places first where famine and want of employment\nwere most severely felt,[24] and that in such places and under such\ncircumstances, it was most prevalent and fatal. The physicians generally\nbelieved it to have been spontaneously produced and not to have been\nimported. In the last Famine Fever of Ireland, Liverpool and several other\nplaces suffered severely from the {61} importation of their Channel\nneighbours with the disease in some instances, and the infection in others\nabout their persons. Hitherto these have to all appearance been the limits\nof the affection; we know not, however, how soon the time may come when the\ninvisible bonds which have thus chained the disease to certain localities\nmay be severed, and spreading itself like other pestilences in an\naggravated form, attack this country as a last and crowning act of\nretributive justice. At present it has but cost us money and regrets, but\nif the history of pestilences is to be heeded, there are many tokens which\nseem to indicate that a few slight concurrent circumstances only are\nwanting, to bring the full force of this disease upon us; then will there\nbe a sacrifice of life. Edinburgh and other towns of Scotland have had some\nvisitations already, ourselves but slightly, but let our labouring\npopulation suffer to any large extent for want of work, and we shall\ninevitably be the sufferers from that fever which in consequence of general\ndestitution is now always more or less prevalent in Ireland.\n\nThe Sweating Sickness prevailed in England alone at first, but at length\nsought foreign victims. The Cholera is an exotic disease, as well as the\nPlague, but they occasionally have visited our shores, and their seeds\nremain among us. The Small Pox is now even not known in some parts of the\nworld, but when once it is established, who can predict the period of its\nfirst appearance in an {62} epidemic form. The history of the disease\ninforms us that in all the countries where it has been introduced, sooner\nor later an epidemic has seized the inhabitants.\n\nA disease previously unknown in India appeared at Rangoon in the year 1824,\nwhich obtained the name of Scarlatina Rheumatica. Four years afterwards it\nattacked the Southern States of North America, and though the disease was\nso impartial as scarcely to spare a single individual of any town to which\nit extended its influence, it was not accompanied with that mortality which\nhas usually been the characteristic of wide spread epidemics.\n\nThere is one peculiar feature of all epidemics which may be here mentioned\nas indicative of some definite, though at present unaccountable cause,\noperating in the sudden suppression of the disease after a certain period\nof duration. This distinctive character may almost be considered as a law\nin reference to these affections; if we take three distinct diseases, the\nPlague, the Irish Fever and the Cholera, we find the rule apply to all. Of\nthe latter disease we have so recently been witnesses, that I need not\nquote authorities on this point concerning it. In Dr. Patrick Russell's\nwork on the Plague at Aleppo I find the following remarkable passage. After\nalluding to the great increase of pestilential effluvia that there must be\ntowards the close of an epidemic, compared with the amount at the onset of\nthe disease, and expressing his {63} astonishment that so many escape\ninfection, he says: \"The fact, however unaccountable, is unquestionably\ncertain; the distemper seems to be extinguished by some cause or causes\nequally unknown, as those which concurred to render it more or less\nepidemical in its advance and at its height.\" He then mentions that in\nEurope the sudden cessation may be partly attributable to the measures\nadopted for preventing its extension; but \"at Aleppo, where the disease is\nleft to run its natural course, and few or no means of purification are\nemployed, it pursues nearly the same progress in different years; it\ndeclines and revives in certain seasons, and at length, without the\ninterference of human aid, ceases entirely.\"\n\nThe expressions of Dr. Harty on this subject, in connexion with the Irish\nFever, would apply as well to all other epidemics: \"It is a fact, that\nthough every diversity of management was resorted to for effecting the\nsuppression of the disease, yet, nevertheless, there was an almost\nsimultaneous and apparently spontaneous decline of the epidemic in the\nvarious and most remote parts of Ireland. It is not an easy matter to offer\na satisfactory explanation of this circumstance, _some general cause must_\nno doubt have influenced the subsidence of the disease, yet that cause\ncould not be atmospheric, inasmuch as the decline, though it might be said\nto be simultaneous, was not sufficiently so to admit of that explanation.\"\n\n       *       *       *       *       *\n\n{64}\n\nSECTION III.\n\nTHE DISPERSION OF PLANTS AND DISEASES.\n\nThe dispersion of Diseases and the dispersion of Plants, exhibit analogies\nwhich might be little expected, on a superficial view of the enquiry.\n\nWe are led to believe, that the earth as a whole, was not covered with\nvegetation in a day, the geological history of this planet is one of\ndevelopment, and though at first sight this expression of opinion may\nappear to savour of doubt in the Mosaic record, a more extended\nacquaintance with the subject, favours rather and confirms Scripture\nhistory.\n\nAs the peopling of the earth has been a gradual process with the animal\ncreation, so has it been also with the vegetable kingdom. We see at the\npresent day, that plants by various means of transit from place to place,\nmultiply themselves on new soils and in new climes, the same with animals.\nBy other means we observe, or can trace, the extinction from various\nlocalities and countries, of members of both the animal and vegetable\nkingdom.\n\nWe learn that originally this planet had a temperature much higher than at\npresent, and that the variation of temperature between the equator and the\npoles, which we now witness, did not obtain in the earlier condition of the\nglobe. We are given to understand, and not without considerable proof, {65}\nif not demonstration, that the earth was a vast bog, in which rank\nvegetation grew, and in which the ichthyosauri and plesiosauri, must have\nfloundered about as unwieldy and loathsome bodies. We can readily conceive\na condition of atmosphere at this time to have been loaded with pestiferous\nvapours of an organized nature; it is entirely in accordance with all we\nknow, that it should have been so. Allied forms of plants to those now in\nexistence, are found in the form of fossils, by which comparisons are made,\nbut how the transition into the present Flora took place, or at what\nperiod, it is impossible to say. That these plants should have been\nentirely destroyed during the revolutions of the earth by earthquakes, and\ntheir consequences; the collection of waters into the vacuities formed, and\ntheir draining off from other places by elevations of the land, is not to\nbe dwelt on without astonishment; then again the ultimate changes of\ntemperature on the surface of the earth, may have been another element in\nthe history of their extinction. But if we may be allowed to imagine that\nthere were organic germs floating in the vapours of the atmosphere, these\nwould hardly be subject to the same influences as those which depended\nsolely on their fixation to the soil for subsistence. The atmosphere, their\nnative element, being influenced by the commotions from below, would be\nagitated; vortiginous currents would be established, hurricanes would sweep\nover the stagnant pool and reeking morass, {66} and the higher regions of\nthe air might have thus given protection to these subtle germs, while\nalmost a total extinction of the elegant ferns, the stately palm, and the\ntowering cane was in course of procedure. Then when the strife of the earth\nand elements had subsided, these would descend with the gentle breezes, and\nagain find in various spots a local habitation--\n\n \"Where blue mists, through the unmoving atmosphere,\n  Scatter the seeds of pestilence _and feed unnatural vegetation_.\"\n\nIn the new era, when the earth took its present physiognomy, who shall say\nwhether much of the pestiferous matter may not have been enclosed and\ncondensed in the bowels of the earth, and when it is remembered, that\nearthquakes and convulsions of nature,[25] have invariably preceded the\noutbreak of {67} any great pestilences, that stinking mists, coming from\nsome unknown regions, and unusual vegetations have made their appearance in\nconcert at these times, what I ask is more natural than to imagine, that\nthey have been let loose during the general convulsion? It may be asked,\nwhat is to be said about that revolution of the earth, when the great\nDeluge spread over the whole face of the globe? It can only be replied,\nthat this is a part of the scheme of cosmogony into which we are not called\nupon to enter. There are yet strenuous supporters of the partial as well as\ntotal submersion of this planet, but whether it be true that the vast\ntorrents which appear to have swept the surface uniformly in a southern\ndirection, were of a date coeval with the deluge, and constituted an\nessential portion of the phenomena, of which one was, that \"the fountains\nof the great deep were broken up,\" or whether they were anterior to this\ncatastrophe, will not at all interfere with the conjecture of a very early\nformation and propagation of the germs of pestilential diseases, for the\ncommotions of a deluge were less likely to interfere with the vapours of\nthe atmosphere, than extensive volcanic and electric disturbances.\nMoreover, it is rather in favour of this theory, that the {68} regions\nwhere the temperature and exhalations most nearly resemble those of the\nformer condition of the earth, are those in which pestilential disorders\nmost frequently arise, and where their virulence has always been most\nstrongly marked.\n\nAfter the various commotions which left the globe, with its present\nphysiognomy of mountains, plains, valleys, rivers, lakes, and oceans; a new\nFlora and Fauna appeared to adorn and animate the scene of man's existence.\nPlants and animals were created apparently in adaptation to the numerous\nclimes, which the seasons in the various latitudes or the elevations of the\nsoil, were prepared to render fruitful and useful each in its own sphere.\nBesides this, the plants of the same latitude, in some instances, differ\nmaterially from each other; in this case it seems that the soil has much to\ndo with this peculiarity, for it is certain that the soil and the\ncontiguous atmosphere, have a close and intimate relation; the drought of\nthe desert depends upon the sand, as humid atmosphere is connected with the\nmorass. To illustrate the tendency which vegetation shews in appropriating\none locality more than another, I may quote the following: \"Some of the\nvolcanic masses of the Aeolian or Lipari Islands, that have existed beyond\nthe reach of history, are still without a blade of verdure; while others in\nvarious parts, of little more than two hundred years date, bear spontaneous\nvegetation, and the same is seen on two lavas of Etna near each other, for\nthe one {69} of 1536 is still black and arid, while that of 1636, is\ncovered with oaks, fruit trees, and vines.\"\n\nIn comparing the diffusion of plants, and the diffusion of diseases, the\ndifferent modes by which this generally has been effected may be considered\nunder heads, that the comparison may be more readily traced.\n\n_First_, seeds are diffused by the atmosphere, either by the prevalence of\ncertain currents, which are produced by known laws, in which case, no\ndifficulty occurs in the explanations; or in a more imperceptible manner,\nas by those more uncertain atmospheric currents of a partial nature, which,\nthough they seem to have laws governing them, are not yet understood.\n\n_Second_, seeds are transported by water across oceans, &c. when they can\nbe floated on any material by which they are preserved, as by wrecks and\nmasses of wood, which have been washed down the rivers.\n\n_Third_, they are conveyed by man to all parts of the globe.\n\n_Fourth_, a period of latency is observed to apply to them, that is, they\nrequire certain essential conditions before germination occurs; so that\neven in some localities, a plant may not have been known to exist in a\nparticular neighbourhood, but by a train of circumstances, it may make its\nappearance, and again be a centre of development.\n\n1st. I shall not here wander into the speculation, {70} whether plants had\noriginally one birth-place, as a centre from which they spread by various\nagencies, as supposed by Linnaeus, nor into any enquiry beyond those facts,\nwhich may fairly come within our own comprehension, and within our own\nmeans of demonstration.\n\nMany seeds are provided with means adapting them for floating in the\natmosphere, these are by pappi, or winglets and hairs, but it cannot be\ndoubted that the agency of atmospheric currents, is productive of\nconsiderable effects in the dispersion of lighter seeds, such as those of\nmosses, fungi, and lichens--lichens have been discovered in Brittany, which\nare peculiar to Jamaica, and Monsieur De Candolle concludes, that their\nseeds had been carried thence by the south-westerly winds, which prevail\nduring a great part of the year on this portion of the French coast.\n\nBut Humboldt's testimony on the subject of winds is most satisfactory, for\nhe says, \"Small singing birds, and even butterflies, are found at sea, at\ngreat distances from the coast (as I have several times had opportunities\nof observing in the Pacific), being carried there by the force of the wind,\nwhen storms come off the land.\" It is generally believed, from abundance of\nproofs, that the trade winds, and other continuous currents, are means by\nwhich plants are conveyed from one country to another.[26]\n\n{71}\n\nAs to the partial currents, Humboldt further says, \"The heated crust of the\nearth occasions an ascending vertical current of air by which light bodies\nare borne upwards. M. Boussingault, and Don Mariano De Rivero, in ascending\nthe summit of the Silla, one of the gneiss mountains of Caraccas, saw in\nthe middle of the day, about noon, whitish shining bodies rise from the\nvalley to the summit of the mountain, 5755 feet high, and then sink down\ntowards the neighbouring sea coast. These movements continued\nuninterruptedly for the space of an hour. The whitish shining bodies proved\nto be small agglomerations of straws, or blades of grass, which were\nrecognized by Professor Kunth, for a species of vilfa, a genus, which\ntogether with agrostis, is very abundant in the provinces of Caraccas and\nCumana.\"\n\nOn the plague of locusts we read, that \"the Lord brought an east wind upon\nthe land, all that day and all that night, and when it was morning the east\nwind brought the locusts.\"\n\nOn the Black Death we read, \"There were many locusts which had been blown\ninto the sea by a hurricane, and a dense and awful fog was seen in the\nheavens, rising in the east, and descending upon Italy.\"\n\nOf the Plague of 542, Gibbon says, \"The winds might diffuse that subtle\nvenom, but unless the atmosphere be previously disposed for its reception,\nthe plague would soon expire in the cold or {72} temperate regions of the\nnorth. The disease alternately languished and revived, but it was not till\na calamitous period of fifty-two years, that mankind recovered their\nhealth, or the air resumed its pure and salubrious quality.\"\n\nIn the history of the Sweating Sickness, of which there were five distinct\nvisitations, we find ample allusions to the atmosphere, and the mode in\nwhich the disease was conveyed by this medium.\n\nI quote again from Hecker: \"It seemed that _the banks of the Severn_ were\nthe _focus of the malady_, and that from hence, a true impestation of the\natmosphere, was diffused in every direction. Whithersoever the winds wafted\nthe stinking mists, the inhabitants became infested with the sweating\nsickness. _These poisonous clouds of mists were observed moving from place\nto place_, with the disease in their train, affecting one town after\nanother, and morning and evening spreading their nauseating insufferable\nstench. At greater distances, these clouds being dispersed by the wind,\nbecame gradually attenuated yet their dispersion set no bounds to the\npestilence, and it was as if they had imparted to the lower strata of the\natmosphere, _a kind of ferment which went on engendering itself even\nwithout the presence of the thick misty vapour_, and being received into\nmen's lungs, produced the frightful disease everywhere.\"[27]\n\n{73}\n\nMr. K. B. Martin, harbour-master of Ramsgate, in a communication to Lord\nCarlisle on the Cholera of last autumn, says, \"At midnight of the 31st\nAugust (1849), the Samson (steam-tug) proceeded to the Goodwin Sands, where\nthe crew were employed under the Trinity agent, assisting in work carried\non there by that corporation. While there, at 3 A.M. 1st September, _a hot\nhumid haze, with a bog-like smell_, passed over them; and the greater\nnumber of the men there employed instantly felt a nausea. They were in two\nparties. One man at work on the sand was obliged to be carried to the boat;\nand before they reached the steam vessel at anchor, the cramps and spasm\nhad supervened upon the vomitings; but here they found two of the party on\nboard similarly affected. Here then is a very marked case without any known\npredisposing local cause. Doubtless it was atmospheric, and in the hot\nblast of pestilence which passed over them.\"\n\nMany more instances might be quoted, to shew that the germs of disease, as\nwell as of plants, are borne on the wings of the wind from place to place\n{74} in one country, and from one country to another, the distance being no\nobstacle, however great that may be.[28] \"Dust and sands,\" says Sharon\nTurner, \"heavier than many seeds, are borne by the winds and clouds for\nseveral hundred miles across the atmosphere, falling on the earth and seas\nas they pass along.\" \"The clouds not only bring us occasionally meteoric\nstones, hail, and _epidemics_, but also vegetable seeds.\"[29]\n\n2nd. The transportation of seeds of plants by water requires very little\nnotice; every one is familiar with the mode in which coral islands, which\ngradually rise out of the sea, become covered with vegetation. \"If new\nlands are formed, the organic forces are ever ready to cover the naked rock\nwith life.--Lichens form the first covering of the barren {75} rocks, where\nafterwards lofty forest trees wave their airy summits. The successive\ngrowth of mosses, grasses, herbaceous plants and shrubs or bushes, occupies\nthe intervening period of long but undetermined duration.\"\n\nThe following may be cited as an instance of the transportation of disease\nby water. \"Cyprus lost almost all its inhabitants, and ships without crews\nwere often seen in the Mediterranean, or afterwards in the North Sea,\ndriving about, _and spreading the plague wherever they went on shore_.\"[30]\n\nIt requires no argument to enforce the conviction that cottons, woollens,\nfurs, skins, &c. will retain the matter of infection for almost an\nindefinite period; instances of the kind have been already given; it is\ntherefore easy to understand that portions of wrecks and ship's goods would\nbe a frequent though unsuspected source of infection. Dr. Halley mentions a\ncase, in which a bale of cotton was put on shore at Bermuda by stealth; it\nlay above a month without prejudice, where it was hid, but when opened and\ndistributed among the inhabitants, it produced such a contagion that the\nliving scarce sufficed to bury the dead. Dr. Walker found seeds dropt\naccidentally into the sea in the West Indies cast ashore on the Hebrides.\nHe says, \"the sea and rivers waft more seed than sails.\" The waters of many\nrivers induce diarrhoea and dysentery.[31] Well water also in many {76}\nplaces has a similar effect, especially if any surface drainage happens to\nfind its way into the well.\n\n3rd. The part performed by man himself in the communication of disease to\nhis fellow creatures, is perhaps the most fruitful source of the extensive\nspread of epidemic and contagious diseases.\n\nIn the time of Moses, restrictions were laid on those who had the plague of\nthe leprosy to avoid contagion; the dictum for one so affected was, \"he\nshall dwell alone; without the camp shall his habitation be.\"[32] All the\nancient authors believed in the {77} infectious nature of pestilential\nfevers, and some other diseases; but, according. to Mr. Adams, they held\nthat no specific virus was the cause, and merely a contamination of the\nsurrounding air by effluvia from the sick. Thucydides, Hippocrates,\nProcopius, Galen, Plutarch, all recognized the property of communicability\nfrom one individual to another of the plague; and Hecker, on the epidemics\nof the middle ages, abounds with instances in support of contagion. As\nregards small-pox and measles, Rhazes observes particularly the connection\nthat exists between the condition of the air and the severity or mildness\nof these diseases, remarking that small-pox seldom happens to old men,\nexcept in pestilential, putrid, and malignant constitutions of the air in\nwhich this disease is usually prevalent.\n\nThe history of the introduction of Scarlet Fever, Hooping Cough, Lues, and\nother diseases into the various countries of the globe, is sufficiently\nconvincing that men carry about with them the seeds of disease; that while\nthese attach themselves to the persons and clothing of those who introduce\nthem into new climes, and flourish independently of cultivation, yet the\nexotics which they foster with so much care, often disappoint their most\nsanguine expectations; and these \"languishing in our {78} hothouses can\ngive but a very faint idea of the majestic vegetation of the tropical\nzone.\" Art in this procedure fails to accomplish here, what nature but too\nsadly, under some circumstances, effects most readily. The germs of some\ndiseases though of an exotic character, under congenial influences of\nvarious kinds, appear to flourish with native vigour: is it not so, also,\nwith some forms of vegetation? The aloe, a native of Mexico, which lives,\nbut does not thrive well, or reproduce under ordinary circumstances in this\ncountry, will occasionally send forth a most luxuriant blossom;[33] so rare\nis this, that some say it occurs every 50 or 100 years, but no law seems to\nbe established on this point, any more than the statement that we may\nexpect pestilential diseases at certain intervals. But that there are\nintervals of _uncertain_ duration when the aloe will blossom, when the\ngrapes will ripen, and a general productiveness of exotics will occur, is\nas certain as that seasons will occur when contagion will be rife, and a\nmost unusual multiplication of disease prevail. This is not an imaginary or\nspeculative notion,--all observers of seasons and diseases within the last\ntwenty years, may fully verify the statement.\n\nIn 1846, a large vine, the black Hambro-grape, {79} ripened its fruit out\nof doors, and was as fine as any green-house production; but during nine\nyears that the vine has been under my inspection, this was the only time I\nhave witnessed such a result.\n\nWe are apt to attribute an abundant or scarce fruit season to temperature\nalone, but this is an error--for we have before remarked, that though\ncertain lands may be in the same degree of latitude, the plants which\nthrive well on one land, will not do so on the other: in fine, that where\nreason and analogy would lead one to expect a particular form of\nvegetation, a totally different Flora is presented to the view. These facts\nare indeed suggestive of new and important deductions. Is it yet explained\nwhy the town of Birmingham should be free from Cholera? There is a large\nmanufacturing population, a great number of poor, the usual overcrowding of\nindividuals in small chambers, a considerable amount of destitution and\ndepravity; irregular habits of living, and unwholesome diet, and doubtless\nmany parts of the town, which on investigation would have yielded all the\nelements usually considered necessary for the localization of the disease:\nbut no--here was some repelling cause, some opposing agent to the\ngeneration and propagation of the pestilential seeds. There are no known\nlaws by which inorganic matter could be supposed to observe such a\nselection, or such an antagonism. Electricity, magnetism, ozone, gases,\nexhibit no such elective properties that here they will destroy, and {80}\nthere they will spare; that they can almost depopulate small villages, and\nscarcely find a victim in Birmingham and Bath. But if we suppose a living,\nand multiplying matter as the cause of disease, many local causes may\nconspire to arrest the development of the germs, or perhaps, even utterly\ndestroy them.\n\n4th. As to the time of latency, facts crowd upon us indefinitely, as\nelements of comparison between vegetation generally, and disease in its\nearly stages and history. The seeds of plants are extraordinarily tenacious\nof life. What a mysterious arrangement of the ultimate particles of matter\nmust there be, by which the vital force remains apparently inactive for\nmany years, and yet when the conditions arise favourable to its\nmanifestation, as it were by an extraordinary fiat, life appears.\n\nPrevious to the year 1715, no broom grew in the King's Park, at Stirling;\nbut in that year a camp was formed there, and the surface of the ground\nconsequently was broken in many places. Wherever it was broken, broom\nsprang up. The plant was subsequently destroyed; but in 1745 a similar\ngrowth appeared after the ground had been again broken for a like purpose.\nSome time afterwards the park was ploughed up, and the broom became\ngenerally spread over it. \"In several places in the neighbourhood of\nEdinburgh,\" says Professor Graham, \"the breaking of the surface produces an\nabundant crop of Fumaria parviflora, {81} although the same plant had never\nbefore been observed in the neighbourhood. It is impossible to say the\nlapse of time since these were buried, before they were again excited to\nthe performance of all their vital functions.\" Dr. Graham also gives\nanother proof of the vital force existing in seeds. \"To the westward of\nStirling there is a large peat bog, a great part of which has been flooded\naway by raising water from the River Teith, and discharging it into the\nForth,--the under soil of clay being then cultivated. The clergyman of the\nparish standing by while the workmen were forming a ditch in this clay,\nwhich had been covered with fourteen feet of peat earth, saw some seeds in\nthe clay which was thrown out of the ditch; he took some of them up and\nsowed them: they germinated and produced a crop of Chrysanthemum septum.\nWhat a period of years must have elapsed while the seeds were getting their\ncovering of clay, and while this clay became buried under fourteen feet of\npeat earth!\"[34]\n\n{82}\n\nWhat limit can there be to the dispersion of seeds when their vital\nproperties may remain so long unimpaired? The seeds of which we have been\nspeaking were, no doubt many of them, washed away with the waters of the\nTeith, and carried by the stream into the Forth; and who shall then mark\ntheir destination; for we have seen that by such means the most distant\nlands are supplied with vegetation; for whence come the plants which cover\nthe Coral Islands, unless by the air and the water, and that both\ncontribute, has been incontestably proved. Dr. Lindley states that melon\nseeds have been known to grow when forty-one years old; maize thirty years,\nrye forty years, the sensitive plant sixty years, kidney-beans a hundred\nyears. But seeds in general have an indefinite period, apparently, at which\nthey can retain their power of germination; for many of the seeds which had\nbeen kept in the herbarium of Tournefort for more than a century, were\nfound to have preserved their fertility.\n\nIt has now to be shewn that the germs of disease also retain their vital\npowers in a state of dormancy during a lengthened period.\n\n{83}\n\nMead has very judiciously observed, \"to breed a distemper, and to give\nforce to it when bred, are two different things.\" He further remarks, that\nthe seeds of the Plague may confine themselves to a house or two during a\nhard frosty winter, and be preserved, and again put forth their malignant\nquality as soon as the warmth of the spring gives them force. It is\ncertainly very remarkable that the Plague of London, which commenced at the\nlatter end of the year 1664, should \"lie asleep,\" as Mead says, from\nChristmas to the middle of February, and then break out in the same parish.\n\nIt has been also known that an infected bed laid by for seven years had\ndone infinite mischief on being again brought into use. Indeed, it is quite\nuncertain for how long a period woollen, fur, linen, cotton, and other\narticles may retain infectious matter in a dormant state. It has been\nsupposed by some that in closely packed bed and body clothes a\nmultiplication of the germs may and does take place, nor do I see any\nreason why this should not be the case, for these articles contain within\ntheir structure the effluvia of the animal body, and they may possibly\nthere find sufficient nutriment for their development. Nees von Esenbeck\nbelieved that some of the minute Cryptogamia were re-produced in the air,\nwe are not therefore exceeding philosophical conjecture when we imagine a\nbasis and substratum, though an unusual one, for the germs of vegetation.\nExclusion from air and light, {84} however, as would be the case in\npacked-up clothes, would _a priori_ give a better colour to the conjecture,\nas these are the usual conditions necessary for the growth of seeds.\n\nSmall Pox and Cow Pox matter, which are now proved to be the same virus,\nthe former modified by having been through a process of growth and\nmaturation in the cow, are both remarkable for exhibiting their active\nproperties after having lain dormant for a considerable time. And each,\nthough so closely allied, retaining its specific properties.\n\nThis peculiarity in the history of Small Pox virus suggests a comparison\nwith some phenomena of vegetation, _viz._ that of grafting or budding. The\nlower Cryptogamia in their fructifications resemble rather multiplication\nby buds than by seeds. M. Moyen's idea is that every spore or little\nglobule, independently of its neighbouring one, lives, absorbs,\nassimilates, grows, and re-produces on its own account; this is certainly\nthe characteristic of the Torula and the Uredo, and doubtless is so of many\nother of the Cryptogamia, the Protococcus nivalis is another instance.\nOther modes of cultivation produce also great varieties of results of an\nunexpected kind.\n\nWould any one, says Dr. Walker, imagine that cabbage, cauliflower, savoy,\nkale, brocoli, and turnip-rooted cabbage, were the same species? yet\nnothing is more certain than that they are only varieties produced by the\ncultivation of the Brassica oleracea, {85} a plant which grows wild on the\nsea-shores of Europe.\n\nThese varieties in vegetables have now become permanent, and though it is\nsupposed that each is liable to return to its original condition, I am not\nyet certain that such is the tendency. A deterioration is not unlikely to\nensue in the course of time, because the propagation by seeds must\nnecessarily very much approach the system of intermarriage, on which Mr.\nWalker has so ably written and clearly shewn that as a result we may\ninvariably expect a deterioration of the species. Dr. Darwin has also\npoetically described what his experience taught him.\n\n \"So grafted trees with shadowy summits rise,\n  Spread their fair blossoms and perfume the skies,\n  _Till canker taints the vegetable blood_,\n  Mines round the bark and feeds upon the wood;\n  So years successive from perennial roots,\n  The wire or bulb with lessened vigour shoots,\n  Till curled leaves or barren flowers betray\n  A waning lineage verging to decay;\n  Or till amended by connubial powers,\n  Rise seedling progenies from sexual flowers.\"\n\nThe minute nature of the germs of disease preclude all possibility of their\nbeing submitted, as far as we know at present, to the inspection of the\nphysiologist, but we may infer many facts from results. In the same way,\nthough with humbler {86} ideas, as Cuvier could build up an animal from a\nsingle bone, can we by a combination of facts infer the existence of living\nbeings and conjecture their forms. \"The re-production or generation of\nliving organized bodies is the great criterion or characteristic which\ndistinguishes animation from mechanism.\" We find the virus of Small Pox,\naccording to Mr. Ceely's experiments, developing itself as a constitutional\ndisease upon the cow, and becoming modified into a form known as the Cow\nPox; this resembles the process of cultivation by which a species is\nconverted into a variety, this variety remains for a certain time\npersistent; the time is not yet known, but it is known that by degrees, as\nstated above, a deterioration occurs, and fertility becomes impaired, \"a\nwaning lineage verging to decay,\" and this has been observed as a feature\nin the result of vaccination. I believe Dr. Gregory was one of the first to\nnotice this fact, and deemed it necessary to obtain fresh lymph from the\ncow; this has been done, and it is not improbable, if the analogy we have\ndrawn be correct, that the slowly spreading scepticism regarding\nvaccination may be arrested in its progress. If we can explain the\ndeterioration of cow pox virus on this principle we have a hold at once\nupon the public, and can assure them that the efficacy of the proceeding is\nas certain as in the time of Jenner. The people, I contend, have a right to\ndemand of us the reason why vaccination is not so efficacious as formerly,\nand I {87} affirm as unhesitatingly that we are bound to give the subject\nour most earnest attention.[35]\n\nNow concerning the re-production of Cow Pox matter, and assuming it to\nresemble that of the lower Cryptogamia, we can easily understand how\ndegeneration in a course of years should ensue, for we find that though the\nSmall Pox is a constitutional disease, that produced by vaccine lymph is a\nlocal affection, so that it bears the relation that grafting does to\nvegetation, and it is not improbable that such a modification takes place\nin the germs by passing through or becoming generated in the blood of the\ncow, that they entirely lose their original and characteristic form of\nreproduction: the seeds of the disease were originally capable of\nvegetating, if I may be allowed to use the term, by diffusion through the\natmosphere; they now, however, have lost that property, and require to be\ngrafted to exhibit any manifestation of vitality.\n\nHow often will the seeds of a cultivated fruit grow? If you bud it upon\nanother plant, you obtain a being exactly like the parent, but this, as we\nhave seen, deteriorates in a course of years, we have also seen that the\nvirus deteriorates; but not to stretch this point to an unseemly length, I\ncannot avoid expressing my conviction, that these are elements of\ncomparison, possessing an interest and a practical utility of no small\nvalue.\n\n{88}\n\nI have before said, that the reproduction in the Cryptogamia, rather\nresembles budding than seeding. If we observe the Torula, or take the\nprocess of all formation, generally it will be found to accord more exactly\nwith the budding than the seeding process, and this peculiarity is not\nconfined to vegetation, it is also a marked feature in the reproduction of\ninfusoria, sponges, polypes, &c.\n\n    \"New buds surround the microscopic plant.\"\n\nThe reproduction of plants and animals appears to be of two kinds, solitary\nand sexual; the former occurs in the formation of the buds of trees, and\nthe bulbs of tulips.\n\nThe microscopic productions of spontaneous vitality propagate by solitary\ngeneration only.\n\nWe have but reached the threshold of this vast and interesting subject, the\nexperiments which suggest themselves to the mind while reflecting upon it,\nwould alone occupy a whole life of leisure, and I can but feel how forcibly\nMr. Sewell's words apply to us: \"The grand field of investigation lies\nimmediately before us, we are trampling every hour upon things which to the\nignorant seem nothing but dirt, but to the curious are precious as gold.\"\n\nIt is difficult, perhaps, to bring many instances, in which the germs of\ndisease have lain dormant for a lengthened period, because many may take\nexception to them, from the fact, that sporadic cases of {89} most epidemic\nand infectious diseases, are rarely absent from any country in which those\ndiseases have become indigenous, and these cases may be said to be the foci\nwhence originates the epidemic constitution of the air; this, however,\nwould not invalidate the supposition, because one of two inferences must be\ndrawn, either that the germs of disease always exist in a dormant state,\nrequiring circumstances and conditions only for their development, or that\nthe germs are imported from some distant locality, where the disease has\noccurred, and finding a nidus there, grow and multiply.[36] Whichever\nnotion we take, however, matters very little to the fact of the dormancy of\nthe germs, for in both, a certain period elapses between their transmission\nand their propagation. It may fairly be presumed, that sometimes one method\nmay apply {90} and sometimes the other, perhaps both during general\nepidemic conditions of the atmosphere.\n\nThe Oidium vitis attacked the vines partially last year, and I believe\ngenerally spared other forms of vegetation; but this year in my vicinity,\ncucumbers, melons, and vegetable marrows, are all suffering more or less\nunder the disease.[37] How shall we say, whether are the seeds of last year\nthe cause of the general diffusion at the present time, or were there a\nsufficient number of old and dormant seeds, universally diffused, and only\nwaiting opportunities for multiplying themselves? We are here on the horns\nof a dilemma; and spontaneous generation, from which one naturally shrinks,\ncan alone extricate us, if we do not admit diffusion and dormancy. I think\nI may, without undue assumption, affirm that a period of latency of\nindefinite duration, applies as cogently to the germs of disease as to\nthose of plants.\n\nThere is yet one other point in connection with this subject, and that is\nthe apparent extinction of some diseases, at any rate their non-appearance\nin certain localities, which had been at one time congenial to them, and in\nwhich they flourished. We have seen, in illustrating the dormancy of seeds,\nthat the broom must have been a common plant at {91} some considerable\nperiod back, in the King's Park at Stirling, or on that site.\n\nThen again, the appearance of Fumaria parviflora in the vicinity of\nEdinburgh, in several places where the ground is broken, is sufficiently\nconvincing that this plant must once have been a common form of vegetation\nthere; and as it had never before been observed in the neighbourhood, there\nmust have been a combination of peculiar circumstances capable of rendering\ngermination impossible, otherwise a continued multiplication, as in other\nforms of vegetation, would have followed of necessity.\n\nBut besides these instances, how many are passing under our own eyes of the\ndisappearance of plants under the influence of cultivation, and the\ngeneration of the noxious fumes arising from different and innumerable\nmanufactories. In the vicinity of large cities and manufacturing towns, how\nrarely do we see healthy vegetation; shrubs and animals drag on a sickly\nand almost unprolific existence, and their term of natural life is much\nshortened.\n\nAnd if we compare diseases with this peculiar feature of vegetation, how\nvery close do we find the analogies. The Sweating Sickness which appeared\nin the latter part of the fifteenth century, and at certain intervals\nmultiplied and extended itself at first only in this country, but\nultimately more or less over the continent of Europe, has {92} never since\nthe year 1551 shewn any symptom of productiveness, indeed for all we know\nthe disease may be extinct; on the other hand, it is impossible to say\nwhether or not circumstances may arise, under which it may commence again,\nto put forth its energies and again desolate the land.[38]\n\nSince 1665, the Bubo-plague has not found a congenial soil in this country,\nor if the seeds be here, which is more than probable, the necessary\nconditions to excite them to activity do not exist.\n\nIt cannot be imagined that with all the merchandize which comes into this\ncountry from the Mediterranean, but that an abundance of the germs of the\ndisease are annually brought into our ports, and disseminated throughout\nthe land. The law by which we have seen that they possess a power of\nvitality and reproduction, holds now as it did in former times;--the\nproperties of matter never alter, but the conditions under which they exist\nmay be so modified, as to influence their properties, and the usual course\nof their operations. It is therefore to {93} an alteration or modification\nof conditions that we are to look for the exemption, during the last two\ncenturies, from an invasion of the Plague. To say what those conditions may\nbe in their totality is difficult, perhaps impossible. We may generalize on\nthe subject, and imagine the reason discovered, but all those causes which\nwere said to have conspired to favour the spread and contamination with\nPlague, were as distinctly specified and attributed, as the cause of our\nlate infliction with Epidemic Cholera. Why then did we have the Cholera and\nnot the Plague? To what particular element was it--in the mode of living,\nof destitution, of filth and want of drainage--can it be ascribed that we\nsuffer under one disease, and not under the other?\n\nWe have made some few observations and comparisons on the mode of\ndispersion of plants and diseases,--but there is yet one more point which\ninvites notice. Not only do seasons vary in their effects on vegetation in\na remarkable and unexplained manner, but there are many localities to which\nsome special form of vegetation attaches, and which appear to have a power\nof exclusion of other forms; and as yet I have not been able to trace the\nconnexion, nor can I discover it in the writings of botanists and\ntravellers, who would be most likely to have sought an explanation of so\ninteresting and curious a fact. Dr. Prichard has on this subject some very\napposite illustrations. \"Still further southward, the austral temperated\nzone completely {94} changes the physiognomy of vegetation, and the Isle of\nNorfolk has, in common with New Holland, the Auracania found also in the\nharbour of Balade, and with New Zealand, the Phormium tenax. It is however\nremarkable, that this vast island, composed of two lands, separated by a\nchannel, though so near New Holland, and lying under the same latitude,\ndiffers from it so completely, that they display no resemblance in their\nvegetation. Yet New Zealand, so rich in genera peculiar to its soil, and\nlittle known, has some Indian plants: such as Pepper, the Olea, and a\nreniform Fern, which is said to exist in the Isle of Maurice.\"\n\nI must quote one more passage from Dr. Prichard's excellent work. \"We have\none instance of an island at no great distance from a continent, having a\npeculiar vegetation. Mr. R. Brown has remarked, that there is not even a\nsingle indigenous species characterising the vegetation of St. Helena, that\nhas been found either on the banks of the Congo, or on any other part of\nthe Western coast of Africa. Does the diversity of marine and atmospheric\ncurrents more completely separate this island from the continent, than its\nsituation would imply; or are the nature of soil and other local\ncircumstances, the cause of so marked a diversity? The last supposition\nseems the most probable; because not only the species of plants, but\nlikewise the genera in St. Helena, are different from those of the African\ncoast.\" {95}\n\nWe are not without instances of diseases, observing this peculiarity which\nattaches to plants; but their specific characters have hardly been\nsufficiently considered in reference to climate and situation, together\nwith diet and local influences, to afford us accurate data for comparison.\nIt has, however, been remarked, in every country where Epidemics have\nprevailed, that some districts or tracts of country, though supposed to\npossess all the qualities favourable to the development of the diseases,\nhave nevertheless been entirely or nearly free from them. The following\npassage on the course of the Cholera gives an example of this peculiarity.\n\"Whenever the malady deviated, so to speak, from its normal direction, and\npassed towards the west, it seemed incapable of propagating itself; and\n_died away spontaneously, even in places which appeared to be well fitted\nfor its reception_.--The rich fertile and densely peopled countries to the\nright of the Dneiper, enjoyed an equal freedom from attack, which can only\nbe explained by the fact that they were situated _beyond the line of the\ndisease_.\" With this I close the subject of the diffusion of plants and\ndiseases, though it would require a volume of itself, to record all that\nhas been noticed. I have endeavoured to select such instances as shall mark\ndistinctly the features which point to comparison without overloading the\nenquiry.\n\n       *       *       *       *       *\n\n{96}\n\nSECTION IV.\n\nTHE RELATION BETWEEN EPIDEMIC AND ENDEMIC DISEASES.\n\nEpidemic diseases, which multiply their germs in any climate, and under\napparently the most varying conditions of temperature and hygrometric and\nelectrical states of atmosphere, offer many points of contrast with Endemic\naffections, and many of relationship. The latter are traceable to a certain\nextent, to geological and geographical positions of the localities where\nthey are observed to prevail, in combination with atmospheric vicissitudes\nand peculiarities, as well as to extent of cultivation of the soil: it has\nbeen remarked that the sickly island (as it is called) of St. Lucia has\ncertain salubrious parts, but these are where sulphur abounds; this\ngeological peculiarity has been deemed sufficient to account for the\nabsence of endemic affections in these parts, and with much force of\nreason; for in the neighbourhoods where sulphur or sulphurous acid, a\ncompound of sulphur, is an element prevalent in the soil or atmosphere,\nvegetation and the ague disappear together.\n\nNow ague, and other endemic fevers, doubtless originate from some allied,\nif not identical cause; for the localities in which they appear have so\nmany {97} features in common, that we are constrained to acknowledge that\nendemic fevers have some relations and analogies, though not yet\nunravelled.\n\nGeographical situation, together with certain vegetation, particularly of\ngrounds which grow rice, is one remarkable for the production of endemic\naffections. But the soil which generates or gives force to the\ncontaminating matter, is not alone the part where human beings feel its\ninfluence most severely. A low marshy ground, prolific of malaria, may be\ncomparatively free; while some neighbouring elevated land, to which\nprevailing currents of air waft the volatile elements of disease, may be\ndesolated by their virulent and concentrated action. \"Malaria may be\nconveyed a considerable distance from its source, _and be condensed_ in the\nexhaled vapour, when attracted by hills or acclivities in the vicinity, and\nwhen there are no high trees or woods to confine it, or to intercept it in\nits passage.\"\n\nThe inhabitants of the city of Abydos were at one time subject to disease,\narising from malaria, generated in some neighbouring marshes; by draining\nthese marshes, which suspended the growth of rank vegetation, the city\nbecame healthy.\n\nRome is in like manner even now subject to fevers, having a similar origin.\nSir James Clark says, \"Among the more prevalent diseases of Rome, malaria\nfevers are the most remarkable, and claim our first notice.\" He considers\nthe fevers to be of exactly the same nature as those of Lincolnshire {98}\nand Essex in this country, of Holland, and certain districts over the\ngreater part of the globe. To the climate, the season, or the concentration\nof the cause of these fevers, he attributes their varieties. It is the same\ndisease, he says, whether from the swamps of Walcheren, or the pestilential\nshores of Africa.\n\nFrom July to October the inhabitants of Rome are most subject to these\naffections.\n\nSir James Clark further says: \"It may be stated as a general rule, that\nhouses in confined shaded situations, with damp courts or gardens, or\nstanding water close to them, are unhealthy in every climate and season;\nbut especially in a country subject to intermittent fevers, and during\nsummer and autumn. The exemption of the central parts of a large town from\nthese fevers, is explained by the dryness of the atmosphere, and by the\ncomparative equality of temperature which prevails there.\"\n\nIn this respect there is a marked difference between an epidemic and an\nendemic affection; for when an epidemic disease attacks a city or town we\ndo not discover that the central parts are more exempt than others; indeed,\nit is rather the contrary; for the most crowded parts of towns and cities\nare those, if not exactly in the centre, which would be comprised in a\nspace nearer to the centre than the circumference; and it has been in those\nparts generally where the epidemic influences seem to have exercised the\nmost potent sway. One would more naturally suppose, that a city surrounded\nby {99} paludal miasm, and not itself being capable of generating the\npoison, should be more affected at the circumference, from the simple fact\nthat the paludal germs, which rise in the air, are suspended in the fogs\nand dews of the atmosphere. These, unless widely dispersed by the winds,\nwould remain within a comparatively confined space; and those situations\nnearest to them would be most subject to their influence. Besides, it has\nbeen shewn, that a small wood or hill, or even a wall, has been sufficient\nto cut off or obstruct the paludal miasm.\n\nWithout enumerating all the known endemic diseases, two or three may be\nalluded to for our present purpose; viz. that of shewing that endemic and\nepidemic diseases have a similar origin.[39]\n\nIt is well known that under certain favouring conditions an endemic may\nbecome a malignant and pestilential disease; that Yellow Fever, which is\nalways endemic in the west, Cholera in the east, and the Plague in the\nsouth of Europe and north of Africa, every few years takes on an epidemic\nform, and desolates considerable tracts of country.[39]\n\nThe Pestilence which raged in the summer and autumn of 1804 in Spain,\ncommenced at Malaga, and remained for a considerable time confined to its\n{100} boundaries, in consequence of the measures of precaution that were\nused, in preventing all communication between the inhabitants of the\ninfected city and those living in the surrounding country. It was only in\nconsequence of persons escaping through the cordon, and passing into the\ninterior of the country, that the disease spread, and extended its ravages\nto distant places.\n\nIt appears to be quite clear, that this disease may properly be considered\nin the first instance of endemic origin; but the tendencies, atmospheric\nand otherwise, were such as to favour its multiplication in other districts\nthan that in which it first came into active existence. From this we may\ninfer, that the seeds of the disease were dormant, and only became roused\ninto vital activity by fortuitous circumstances. Dr. Rush states, that the\nendemic disorders of Pennsylvania were converted, by clearing the soil, to\nbilious and malignant remittents, and to destructive epidemics. Dr. Copland\nsays, it has been observed, especially in warm climates, and in hot seasons\nin temperate countries, that when the air has been long undisturbed by high\nwinds and thunder-storms, and at the same time hot and moist, endemic\ndiseases have assumed a very severe and even epidemic character.\n\nDr. Robertson also confirms this view. \"Endemic diseases, in cases of\nneglect and preposterous management, are found to become more malignant\neven in the most temperate climates; and to {101} generate a matter in\ntheir course, capable of producing a particular disease in any\ncircumstances. _Indeed the origin of every_ contagious fever unattended\nwith eruptions, with the exception of Plague, must commence in this way.\"\nWhy Dr. Robertson should except eruptive Fevers and Plague I cannot\nunderstand, for they must have had a commencement; and their many points of\nsimilarity indicate, if not an identical, an analogous source to other\nendemic fevers.\n\nIt will doubtless be generally acknowledged that endemic and epidemic\ndiseases depend upon some unknown agents, having their source in malarious\ndistricts, and being capable of assuming either a contagious or\nnon-contagious character, according to circumstances.\n\nIf, therefore, we find that under any conditions an endemic affection\nbecomes capable of being propagated by contagion, the same law will hold\nwith regard to it as to the Plague; that the power of reproduction in this\nmatter is evidence of life, according to the doctrine laid down in the\nearlier part of this work. But whether or not infection be admitted, a\nmatter generated in a malarious district, if confined in its effects to\nthat district alone, would not necessarily imply an inorganic nature of the\npoison; for it is difficult to understand how inorganic poison, prevailing\ngenerally over a certain tract of country, could select particular\nindividuals for its victims. If chloroform, chlorine, carbonic acid,\nsulphuretted hydrogen, or even spores of poisonous fungi, (as {102}\nsupposed by Mitchell, which, as he regards their effects, would act in a\nsimilar manner to inorganic compounds) were the agents, all persons would\nsuffer more or less, and the majority be similarly affected. We do not find\nthat uniformity of symptoms, which attend upon the exhibition of poisons in\nthe ordinary acceptation of the term, poisoning. This subject shall be more\nparticularly considered, when treating of the influence of organic germs on\nanimals and plants.\n\nThe history of the Eclair steamer is particularly interesting, as shewing\nthe extraordinary tenacity with which the germs of disease attach\nthemselves to vessels, which we may call floating houses.\n\nThe crew of the Eclair contracted Yellow Fever on the coast of Africa, and\na number of them died. The remainder, sick and well, landed at Bona Vista,\none of the Cape de Verde Islands, and the vessel underwent a process of\nwashing, whitewashing, and fumigating. Nevertheless, on the return of the\nship's company, the disease broke out again with equal intensity, and the\nvessel was ordered home. Sixty-five out of 146 officers and men, who\ncomposed the crew, died of the disease before reaching Portsmouth, and\ntwenty-three were sick at the time of arrival.\n\nEight days after the Eclair left Bona Vista, a Portuguese soldier who had\nmixed with her crew died in the fort which had been occupied by them. Other\nsoldiers then fell sick, and the fort was abandoned. The fever still\nspread.\n\nFrom the 20th September, when the first soldier {103} was attacked, to the\nfirst week in December, the fever continued to rage, and at that period it\nhad found its way into almost all the country villages. The fever was\nbelieved to be the genuine black vomit fever; it proved contagious almost\nwithout exception to the nurses of the sick.\n\nThis is an abstract of Mr. Rendell's letter to Lord Aberdeen, Mr. Rendell\nbeing British Consul at Bona Vista.\n\nNow at the time the fever broke out in the island the weather was\nextraordinarily hot, and much rain had fallen, and the town itself was\nbadly drained and in a filthy state; can it be imagined then that the seeds\nof a disease liable to assume a pestilential character should lie dormant\nor be annihilated under circumstances the most favourable for their\ndevelopment, especially when we know that endemic diseases may assume a\nmalignant character?\n\nThis is just one of many cases which confirm our opinion in this respect,\nthat plants and diseases are not long in making their appearance where the\nsoil and atmosphere are congenial.\n\nThe tenacity with which the disease attached itself to the Eclair is\nsufficiently explained in the absence of due ventilation; in fact, that in\nthe first instance there was no ventilation at all in the hold of the ship.\nThis also the more readily affords a clue to the disaster through all its\nstages, first in the contraction of the disease as an endemical affection\nin the vessel; secondly, in the multiplication of the {104} germs in the\ndamp ill-ventilated hold, in a warm climate; and thirdly, the persistence\nand entire localization of the disease to the vessel when it arrived in the\nclimate of the British shores; while, fourth and lastly, in the unusually\nhot and damp island of Bona Vista, the seeds of the disease were sown, and,\nas we might expect, multiplied indefinitely.\n\nThe consecutive attacks of the crew of the Eclair shew that here a noxious\ngas or a vaporized inorganic poison could not have been the cause of the\ndisease, for as I have before said, in this case the attacks should have\nbeen simultaneous; we find, on the contrary, that as the depressing effects\nof the melancholy condition of the crew was almost hourly undermining the\nhealth of the stoutest of them they as surely became the victims. The\nKroomen, or natives on board the ship had not suffered, shewing that they\nwere inured to the miasm, or were destitute of that condition of blood\nwhich would be favourable to a propagation of the materies of the disease.\n\nThe Eclair we learn had left Bona Vista eight days when the first victim\nbreathed his last; this would give perhaps three or four days for the\nincubation of the disease in the patient, or supposing he had not\ncontracted the germs of the disease before the crew of the Eclair left the\nfort, some local favouring conditions were the means of keeping the germs\nin a fertilizing state, for it is clear from this spot the infection spread\nas from a centre or focus. {105} Such instances as these might be\nmultiplied to extend the length of the enquiry, but, I think, to little\nadvantage. The chief facts to be gathered are that an endemic affection\nbecame epidemic and pestilential, contrary to its usual mode, for the\nPortuguese official physician, on being consulted by the Governor of the\nIsland as to the safety of landing the contaminated crew, said, \"No danger\nat all; I have often brought sick men on shore coming in vessels from the\nAfrican coast, and I never knew any ill effects to arise.\" Putting the most\nreasonable construction on this emphatic and straightforward language, we\nmay presume that ordinary, remittent, and yellow fever had been commonly\nimported into the island, for it is not to be supposed but that both forms\nof disease must have existed among those sick men who had \"_often been\nlanded_,\" under the sanction of the Portuguese physician.\n\nTo take another instance; intermittent fever or ague, is a disease known\namong almost all nations of the world, but it usually occurs in the endemic\nform only. It is universally supposed to depend entirely upon marsh\neffluvia, and we are accustomed to consider it as attaching only to low\nlying countries;[40] but this is not always the case, for disease in {106}\nthis respect, like vegetation, may be found in various latitudes, to\naccommodate itself at varying altitudes, to the temperature and climatic\nrelations, so as to appear indigenous. But though our prejudices are in\nfavour of a simple miasmatic source of ague, as its sole cause, there are\nsome who believe in its infectious nature. M. Sigaud, in his work on the\nClimate and Diseases of Brazil, speaks of Epidemics of _grave intermittent\nFever_, and Dr. Copland says, that the epidemic prevalence of ague is a\nbetter established fact than its infection, and has been admitted by most\nwriters.[41] We have, therefore, but to go one step further to arrive at\ninfection, after having found that an endemic disease under peculiar\ncircumstances, though but rarely, becomes {107} epidemic. The number of\npersons attacked by ague in a malarious district, in proportion to the\npopulation, is not so great as might be expected, considering that they are\nalways subject by night and day, more or less, to respire the air\ncontaining the germs of intermittent fever; we might, therefore, deny the\npaludal source of the affection, as reasonably as deny infection, if we\nfound that occasionally, persons, though subject to all the usual\ninfluences, yet escaped all injurious consequences.\n\nThere are grades and varieties of infectious diseases, from the most\ninveterate to the most mild and doubtful; but that all, without exception,\nwhich can in any way be traced to a specific generating and organic cause,\nmay assume an exalted infectious character, and that the most inveterate,\non the contrary, may more resemble the mild and doubtfully infectious\nforms, is a conviction that must be forced on all who pursue this enquiry\nwith unbiassed interest.\n\n       *       *       *       *       *\n\n\n{108}\n\nCHAPTER III.\n\nTHE REASONABLENESS OF THE APPLICATION OF THE FACTS TO THE INFERENCE.\n\n--------\n\nSECTION I.\n\nTHE CHEMICAL THEORY OF EPIDEMICS UNTENABLE.\n\nIt has been inferred that the germs of disease possess the property of\nvitality, and a number of facts have been adduced to support the\nproposition that vitality is the indwelling force by which the matter\ngenerating epidemic and endemic disease exercises its influence over man\nand animals. The reasonableness of the application of these facts to the\nend in view has now to be considered. Chemistry cannot account for\nepidemics.\n\nOur first subject of reflection points to the chemical discoveries of the\nlast few years, and particularly to those of the great German chemist\nLiebig. We find in the first paragraph of his Organic Chemistry applied to\nPhysiology and Pathology, the following words: \"In the animal ovum, as well\nas in the seed of the plant, we recognize a certain remarkable force, _the\nsource of growth_ or increase in the mass, _and of reproduction_ or of\nsupply of the matter consumed; a force in a state of rest. By the action of\nexternal influences, by impregnation, by the presence of air and moisture,\nthe condition {109} of static equilibrium is disturbed. This force is\ncalled the _vital force_, _vis vitae_, or vitality.\"\n\nThe doctrine of Liebig, that the vital force manifests itself in two\nconditions, or rather, that it is known to be in two different states, that\nof static equilibrium as in the seed, and in a dynamic state, as in that of\ngrowth and reproduction, is perfectly applicable to the germs of disease;\nthe static equilibrium is referrible to the matter of vaccine lymph when\ndried and preserved for use, and the dynamic forces of the matter are known\nto be in operation during its reproduction and growth in the system of the\nvaccinated child.\n\nThen as to reproduction of matter by any chemical process, our author can\nfurnish us with no examples, for even in his explanation of the causes of\ndisease he is quite silent on this point, merely acknowledging that\ndiseased products must be either rendered \"harmless, destroyed, or expelled\nfrom the body.\" He further says, that \"in all diseases where the formation\nof contagious matter and of exanthemata is accompanied by fever, two\ndiseased conditions simultaneously exist, and two processes are\nsimultaneously completed,\" and that it is by means of the blood as a\ncarrier of oxygen that neutralization or equilibrium is established. Liebig\nthus admits that an agent exists in the blood, capable of deteriorating it\nat the expense of the oxygen, which he maintains is contained in the red\nglobules; he further acknowledges that two processes of diseased {110}\naction are going on at the same time, and though he does not explain them,\nI imagine him to mean that new contagious matter is generated and\neliminated from the blood, and that at the same time, there is that\ncondition of body which he would call simply a diseased state, and\ncharacterizes it thus: \"Disease occurs when the sum of vital force which\ntends to neutralize all causes of disturbance, (in other words, when the\nresistance offered by the vital force) is weaker than the acting cause of\nthe disturbance.\"\n\nIf I rightly apprehend his notions, they perfectly harmonize with my ideas,\nto a certain extent, on the subject. They accord, at any rate, most\ncompletely with the theory attempted to be established, and fully confirm\nthe reasonableness of the application of the facts recorded to the\ninference drawn from other sources. The difference only rests on the\nquestion whether vitalized or non-vitalized matter is the _fons et origo\nmali_.\n\nHow is the production of new matter, resembling that originally causing the\ndisease, to be explained by any known hypothesis, except on the assumption\nof living organized matter? Though Liebig and Mulder both deny the fact,\nthat the Torula cerevisiae is the sole agent in the process of\nfermentation: they both equally fail in shewing upon what it does depend,\nand their difficulty rests entirely on their incapacity to explain the\nuniform reproductive properties of the matter engaged in this, as well as\nin all other allied operations. Liebig's statement {111} however on this\nmatter requires notice--he says, \"that _putrifying_ blood, white of egg,\nflesh and cheese, produce the same effects in a solution of sugar, as yeast\nor ferment. The explanation is simply this; that ferment or yeast is\nnothing but vegetable fibrine, albumen or caseine, in a state of\ndecomposition.\"\n\nThis state of decomposition, however, involves a much more complex\nproceeding, than simply a reduction of matter into its elementary forms of\ngases, earths, and minerals; for we nowhere find decomposition of this kind\ngoing on without the development of some organized bodies, either animal or\nvegetable: and since we have seen that the spores of the cryptogami are\nalways in existence in the atmosphere, and making their appearance under\nfavouring conditions, and especially when we find that fermentation is\ninvariably accompanied, and I may safely say, preceded by the deposition in\nthe fluid of the sporules of the Torula, we can hardly believe that they\nare any other than the sole agents of the process. I have now a\nconsiderable quantity of the Torula obtained from the urine of a diabetic\npatient, in which they appeared, as it were, spontaneously. After the urine\nhad been allowed access to the air for a certain time, and the whole of the\nsaccharine matter was converted into new compounds, reproduction of the\nTorula ceased;--and those which remained when the process was completed,\nstill continue as organic cells, deposited {112} in the bottle in an inert\nstate, but ready, on the addition of fresh sugar, as has been proved, to\nresume an active existence. These germs, it is now well known, may be dried\ninto powder, so as to be blown away like dust without any, or but little,\ndetriment to their vital energies; and there is now no doubt that they\nexist in this condition in the air, as do the spores of mucor, aspergillus,\noidium, agaricus, and all other fungi.\n\nMulder, however, does allow some properties to the yeast vesicle; he says,\n\"a variety of strange ideas have been entertained respecting the nature of\nyeast; recent experiments have convinced me that it undoubtedly is a\ncellular plant consisting of isolated cells. They resemble the composition\nof cellulose in some respects, but differ from it in many.\" \"These\nvesicles, consisting of a substance resembling that of cells, do not\ncontribute in the least to the fermentation, but are exosmotically\npenetrated during fermentation by the protein compound.\" These chemists\nseem to have an instinctive horror of allowing any active properties to the\nyeast vesicle, that is as far as the conversion of sugar into carbonic acid\nand alcohol is concerned in the act of fermentation. Dr. Carpenter, as if\ndesiring to conciliate the chemical and physiological disputants, considers\nthat the truth is to be found in the mean of the two extremes,--that is,\nthat the process of fermentation is neither entirely dependent on chemical\nlaws, nor on those laws which preside {113} over the growth of reproductive\nmatter, but is a process in which both perform certain offices, each\ndepending on the other to produce the combined result; he thus approaches\nmore nearly to the theory of Mulder, than that of Liebig.\n\nBut to revert to Mulder, he speaks of the Torula cells being \"exosmotically\npenetrated during the process of fermentation by the protein compound.\" Now\nthe Torula is acknowledged to be one of the Fungals, and the chemical\nconstituents of the Fungi approach very nearly that of animal tissues. They\ncontain a peculiar principle, residing in and obtainable from them, termed\nFungin, which is as highly azotised as animal fibre. The protein compound\nalluded to, Mulder says, is not gluten, because insoluble in boiling\nalcohol, and not albumen, because it is very readily dissolved in acetic\nacid, and he regards it as a superoxide of protein. This superoxide of\nprotein can only have been produced by a vital action in the cells of the\nTorula, and as the fungi consume oxygen, and give out carbonic acid, we\nclearly have all the elementary conditions for their growth in almost all\ndecomposing animal and vegetable matters. It is the nature of the fungi to\nlive on organized matter, but always when it has a tendency to decay; it is\nfor this reason they have been called \"Scavengers.\" Again, we can\nunderstand why some animalized or nitrogenous matter should be necessary\nfor fermentation, otherwise fungi could not grow, nitrogen being an\nessential constituent of {114} their structure, and further fermentation\ndoes not commence without the presence of oxygen, and like as in animals,\nthis gas supports their existence. The conversion of sugar into alcohol is\nrepresented by the following formula:--\n\n                             RESULT.\n              Sugar.  Alcohol.  Carbonic Acid.\n  Hydrogen      3        3\n  Oxygen        3        1            2\n  Carbon        3        2            1\n\nIf therefore the process were merely of a chemical nature, where is the\nnecessity for atmospheric oxygen to accomplish the end? it is quite certain\nthat fermentation cannot go on without its presence. Let us compare the\naction of ferment or yeast in a dried state to the action of albumen, which\nLiebig says is sufficient when decomposing to set up fermentation. \"The\nwhite of eggs when added to saccharine liquors requires a period of three\nweeks, with a temperature of 96deg F. before it will excite\nfermentation.\"[42] But any saccharine liquor on exposure to the air, though\nentirely destitute of albumen or gluten, will ferment, and the Torula may\nbe found in it. I have found the Torula in a great variety of syrups which\nhave spontaneously undergone fermentation. I have also discovered that the\ndevelopment of the cells is delayed or accelerated by the nature of the\ningredient used in flavouring {115} the syrups, with other peculiarities\nwhich need not here be mentioned.\n\nBut the conversion of starch into sugar by means of gluten requires some\nnotice, as by some persons it is associated in their minds with the organic\nprocess of fermentation.[43] Mulder ascribes the latter in the first\ninstance to the action of heat, evidently believing that the\npseudo-catalytic operation of gluten upon starch is the type of all such\nactions, and regarding them all as simply chemical, but we here distinguish\na wide difference; in the latter instance the gluten is decomposed, and\nrendered unfit for a repetition of the chemical phenomenon, and if it is\ndesired to renew the action fresh gluten must be obtained, and a certain\ntemperature kept up, otherwise the experiment fails. How different is\nfermentation: in the ordinary temperature of the atmosphere the yeast\nvesicle will multiply, no incremental or unnatural addition of heat is\nrequisite, and it is one of the commonest and most natural instances of\nvegeto-chemistry: the grape cannot shed its juice, nor the sugar cane its\nsap without admitting these germs, which, under certain {116} conditions\nmultiply themselves and convert the saccharine elements into new compounds.\nThe method by which the conversion of starch into sugar is accomplished is\nthus described by Dr. Ure. He says that if starch one part be boiled with\ntwelve parts of water and left to itself, water merely being stirred in it\nas it evaporates, at the end of a month or two in summer weather it is\nchanged into sugar and gum, bearing certain proportions to the amount of\nstarch used. But \"if we boil two parts of potato starch into a paste, with\ntwenty parts of water, mix this paste with one part of the gluten of wheat\nflour, and set the mixture for eight hours in a temperature of from 122deg\nto 167deg F. the mixture soon loses its pasty character, and becomes by\ndegrees limpid, transparent, and sweet, passing at the same time first into\ngum and then into sugar.\"--\"The residue has lost the faculty of acting upon\nfresh portions of starch.\"\n\nFour points of contrast present themselves for notice as elements of\ncomparison with true fermentation. 1st. The starch solution has to be\nboiled, so that heat, by which it is to be supposed that the starch globule\nis ruptured, seems to be an essential portion of the chemical change, and\neven this may in fact alone be sufficient in such a case to produce some\nelementary change in the starch, and may prepare it for the subsequent\ncatalytic action of some related organic, though not vital material.[44]\n{117} 2nd. Not only a summer heat is necessary, but a period of one or two\nmonths time must elapse before the starch with the water simply becomes\nconverted into sugar, and if artificial heat is to be used to hasten the\noperation, a temperature from 122deg to 167deg F. must be resorted to in\norder to obtain the desired result. 3rd. When even this is accomplished\nthere is no reproduction of the fermenting matter, and artificial and\nchemical means must again be applied to repeat the experiment. 4th. The\nconversion of starch into sugar can be accomplished without the presence of\ngluten at all, by the aid only of temperature and time. It seems to me,\ntherefore, to be entirely unnecessary to occupy more space in the\nelaboration of a proof of the doctrine that the germs of the Torula are the\nsole agents in the conversion of saccharine fluids into alcohol and\ncarbonic acid. By another chemical process starch can be converted into\nsugar, but I am not aware that hitherto any method has been discovered by\nwhich sugar can be converted into alcohol except by the process of\nfermentation proper.\n\nI have been thus particular in commenting on this subject, as it bears, in\nan especial manner, on the question under consideration.\n\n{118}\n\nThe physiologist cannot afford to lose this process from the category of\nchemico-vital, or biochemical manifestations.[45] The philosophy of the age\nhas a tendency to make every thing chemical; it is true that the Divinity\nis as much seen in the laws which govern the elementary particles of\nmatter, as in those laws which preside over the transmutation and\nsustentation of those elementary and inorganic particles, when compounded\nin the tissues which are engaged in the formation of living beings. The\nlaws by which acids and alkalies neutralize each other, and the affinities\nsingle, double and elective, which the particles of matter exhibit,\ntogether with the influences of light, heat, and electricity upon almost\nevery condition of matter, are as truly wonderful as the creative power.\nMan may, in many instances, imitate the processes of nature, he can render\niron magnetic, and form alkaloids, but the {119} laws which govern the\nparticles of matter are still the secret of the whole proceedings. We do\nbut interpret the language of nature in discovery, the book is ever open\nbefore us, and every atom of the world is a word and a theme, capable of\noccupying the short span of sublunary existence allotted to man. We have\nread of \"sermons in stones,\" but a book has been written on a \"pebble.\"[46]\n\nTo return, as we every where in nature find a gradual transition in the\nforms, arrangements and properties of matter, so we may expect to find a\nlink between the inorganic and vital chemistry of nature. The fungi, by\nwhich we contend this transition appears to be accomplished, are also a\nlink in chemical composition, between the animal and vegetable kingdom, and\nnot only in that, but in their subsisting upon matter which has been\norganized, they are deoxidizers and reducers, as the vegetable kingdom in\nits highest function is a compounder. To their functions and offices in the\ngreat scheme of creation, we may fairly apply ourselves with a sure and\ncertain result of the most interesting discovery. Is it no hint that\nwherever decaying organic matter is found, there do we find fungi? is it no\nhint that they are found in all parts of the world? that even in snow the\ngerms of fungi will grow and multiply to such an extent, according to Capt.\nRoss, that the protococcus was seen {120} by him, clothing the sides of the\nmountains at Baffin's Bay, rising, according to his report, to the height\nof several _hundred feet_, and extending to the distance of _eight miles_?\n\nEven stones contain in their interior, or interspaces of their structure,\nthe germs of fungi. A species of Tufa is found in the vicinity of Naples of\na porous texture, which, when moistened and shaded, produces vast\nmushrooms, four or five inches high, and eight or ten inches broad.[47]\nThis author further says: \"In the Maremma, where the volcanic tufa is the\nbasis of the soil the surface is intermixed with the animal remains of\ndeparted empires, and the ordure of cattle, is covered with grasses of old\npasturages, and is wet with heavy dews. Everything, therefore, conspires\nthere to a fungiferous end.\"\n\nThey are found growing in and upon both vegetables and animals. Nees von\nEsenbeck imagined, that minute forms multiplied themselves in the\natmosphere; and really, when we consider the amount of effluvia composed of\nthe atoms cast off from the bodies of living or decaying organic matters,\nwhich are incessantly passing into the atmosphere, the conjecture is not an\nunreasonable one. The minuteness of those, which we know are always found\ngrowing on decomposing bodies, does not preclude the possibility, nay,\nfurther favours {121} the probability, that others infinitely more\nminute,[48] may be destined to remove the more subtle and vaporous\nparticles which escape into the air.\n\nWe can, therefore, I think, conclude, that the lower tribes of vegetation,\nmay consistently be regarded as capable of existing in almost any\ncondition, and almost under any circumstances, they may be made to grow in\nplants by inoculation, as shewn by De Candolle, and Dr. Hassall. If the\nstem of wheat also is inoculated with vibriones, they will make their\nappearance in the grain.[49] If the seed contain them and have not lost its\ngerminating properties, these worms will be found again in the grain. If\nthe grain containing them be dried for years, and moistened again with\nwater, these animalcules, according to Bauer and Steinbach, will present\nall the phenomena of life. This experiment I have witnessed, and can\nconfirm the statement. These animalcules in the diseased grain, have under\nthe microscope the appearance of an immense {122} number of eels crowded\ntogether in a small space, and presenting a movement more, perhaps,\nvermicular than any other, and it is continued for a considerable time. Now\nif these animalcules, or their ova, can be proved to pass with the sap to\nthe seed, there can be no difficulty in comprehending how germs,\nconsiderably more minute and of a vegetable nature, should be found subject\nto the same peculiar mode of obtaining an entrance into animals and\nvegetables for sustenance. \"It is usually imagined,\" says Dr. Carpenter,\n\"that the germs liberated by one plant are taken up by the roots of others,\nand being carried along the current of the sap, are deposited and\ndeveloped, where vegetation is most active.\"\n\nThe chemical theory of disease would be better sustained by a comparison of\n\"the artificial formation of alkaloids,\" and the phenomena of\ntransformation of blood into the tissues of animals, and their degeneration\ninto effete matters, and of sap into the tissues of plants and their\ndegenerations.\n\nProfessor Kopp of Strasburg, says, \"In a chemical point of view, the\nalkaloids are remarkable for their composition, for their special\nproperties, both physical and chemical, and for the interesting reactions\nto which many of them give rise, when exposed to the influence of different\nreagents. Considered medically, the organic bases are distinguished by\ntheir energetic properties. They {123} constitute at the same time, the\nmost violent and sudden poisons, and the most valuable and heroic\nremedies.\"\n\nUpon this very intricate and interesting part of chemical philosophy, it is\nrather dangerous to enter without a thorough and practical knowledge of the\nsubject. This, however, falls to the lot of few men. We, who are engaged in\nthe study of disease, and of the best methods of cure, are obliged to take\nthe investigations of the analytical chemist, and examine them for\nourselves in the intervals of leisure allowed us during the active exercise\nof our calling. Though with less advantages for the study of these\ntranscendental relations of organic and inorganic matter, we are not,\nnevertheless, precluded from forming our opinions on their practical\nbearings to the phenomena and treatment of disease.\n\nThat there is a matter of a poisonous nature concerned in the production of\nendemic and epidemic affections, cannot be doubted by any one; I believe\nindeed, that the chemical theorists admit this, at all events Liebig does,\nfor he says, \"The morbid poison changes in the blood are fermentative, just\nsuch as occur in beer making.\" If we start, then, with the consideration\nthat poisons, in a chemical point of view, are the objects of our research;\nthe obvious course to take is to enquire what is the source of poisons\ngenerally, and what their effects on the animal economy? The mineral\npoisons are entirely excluded from the enquiry by their {124} inaptitude\nfor diffusion, and their uniform effects upon all persons, differing only\nin degree in their operation. The same objections apply to gaseous poisons,\nexcept that to them the property of diffusion would be admitted.[50] We\ncome then to the alkaloids, which constitute, as Kopp says, the most\nviolent and sudden poisons. For the production of alkaloids by artificial\nmeans, organic products of some kind are required. Artificial heat,\npowerful chemical agents or length of time, are, as far as information at\npresent extends, the indispensable requirements to induce these peculiar\nchanges in matter. The only instance I can find, in which elementary\nmatters can by artificial means be combined, so as to resemble the products\nof nature, is that of the conversion of carbon and nitrogen into cyanogen.\nBut the process by which this is accomplished, leads rather to doubt\nwhether it be really and simply by a combination of _elementary_ carbon and\nnitrogen. I extract the following from the Annual Report of the Progress of\nChemistry, for 1848. \"H. Delbruck has performed some experiments on the\nimportant subject of the formation of cyanogen. He confirms the statements\nof Desfosses and Fownes, inasmuch as a _weak but distinct_ formation of\ncyanogen was observed on igniting {125} _sugar-charcoal_[51] with carbonate\nof potassa in an atmosphere of nitrogen.\" The use of sugar-charcoal, may be\nperhaps an explanation of the weak formation of cyanogen, for in these\nnumerous and successive chemical changes of matter, it is impossible to say\nhow many sources of error may arise. The constant contradictions of each\nother, and the opposite statements made by chemists, of equal eminence,\nleave us in a wilderness of doubt, from which we are not likely to be\nfreed, until definite laws shall be discovered to act as a guide in the\ncomprehension of the higher branches of Chemical Philosophy.\n\nBut supposing that the generation of alkaloids could take place in the\nbody, or some analogous poisonous matter, we have yet to imagine a whole\nhost of peculiar and essential conditions to effect this change, besides an\natmospheric agent or agents to set in motion those compositions and\ndecompositions, capable of bringing out these new products from the\nelements of blood. We are aware that in the blood, carbon and nitrogen are\nsufficiently abundant as well as saline compounds, to generate cyanides,\nand, with hydrogen also there in plenty, hydrocyanates, and thus from them\nmany other poisonous products, but how is all this to be effected? And even\nif effected, it is yet a question if such compounds can in any way simulate\nthe attacks of epidemic disease. We have {126} already shewn that the\namount of most poisons necessary to destroy an individual, can be pretty\nclearly estimated, and their _modus operandi_ is tolerably well understood.\nAgain, the most essential part, in which all chemical theory fails, is an\nexplanation of the reproduction of contagious matter.\n\nThe catalytic process, by which decompositions are said to be effected, and\nin which Liebig includes the various fermentations, is one of those\nchemical relations of matter to matter, considered by some as the probable\ncause of infection. Mr. Simon, in a late lecture, has said, \"I consider the\nphenomena of infective diseases, to be essentially chemical, and I look to\nchemistry to enlighten the darkness of their pathology. Qualitative\nmodifications, affecting the molecules of matter as to their modes of\naction and reaction, are such as form the subject of chemical science; and\nthose humoral changes which arise as the result of infection clearly fall\nwithin the terms of its definitions.\" Further on he adds: \"The phenomena of\ninfected diseases appears then, in many respects, to be sui generis.\nCertainly they are chemical. _Probably_ they belong to that _class_ of\nchemical actions called _catalytic_.\"[52]\n\n{127}\n\nIt is not improbable that something resembling a catalytic action may take\nplace in the blood in those diseases of endemic and epidemic origin, but\nthat it can be by a chemical process alone is contrary to all experience of\ncatalytic operations, for except in the instance of fermentation proper,\nthere is no multiplication of the fermentative matter. The action of the\nmatter of contagion seems to stand on the confines between electro-chemical\nand bio-chemical manifestations, and so long as no chemical explanation can\nbe given for the multiplication of the matter of infection, the most\nrational course to adopt is to assume that life under some unknown form is,\nas we every where find it, the sole reproductive agent.\n\n       *       *       *       *       *\n\n{128}\n\nSECTION II.\n\nTHE ANIMALCULAR THEORY OF EPIDEMICS UNTENABLE.\n\nThe animalcular theory of disease, after remaining almost unnoticed for\nnearly two centuries, has been again revived under the auspices of Dr.\nHolland in this country, and Henle of Berlin. And though not entirely\nburied in obscurity, this theory had completely failed to modify the\npractice of physicians in the treatment of those diseases which were\nsupposed to owe their existence to these invisible atoms of created being.\nThe resuscitated notions and all their amplifications, to which the advance\nof science has contributed so much, are threatened with a like fate, an\nabsence of all practical results.\n\nThough I would not attempt to deny the possibility, nay, even the\nprobability, that insect life may yet be discovered as the cause of some\ndiseases,[53] still {129} there are many and cogent reasons against both,\nand which are at variance with facts and observations. Where insect life\nhas been found associated with disease, it more especially appears as a\nconsequence than as a cause.\n\nDisease, in its most enlarged sense, is a conversion of one form of matter\ninto another; it is a transformation of healthy blood and tissue into new\nand abnormal products. Where insects in all their variety of forms are\ndiscovered, their voracious propensities are their chief characteristics,\nthey are the consumers of matter after its partial disintegration, if\nanimal matter be their food, unless they be carnivorous and predacious, or\nif herbivorous they usually feed upon the tender shoots of plants. Thus far\nwe are certain of the manner in which insects destroy living matter; it is\na process the unassisted eye may every where witness, and which experience\nhas amply attested. To take, however, the animalcular world as it presents\nitself to us under the microscope, and as the intermediate step between the\nmanifest and the hidden for a fairer and more direct method of reaching the\ntruth, what do we observe to be the ruling law of infusory instinct? They\nlive to feed; the term polygastrica sufficiently implies their natural\ntendency to consume. The simplest form of animalcular life, seen in the\ngenera of monads, still preserves the animal character by possessing a\nstomach or stomachs in which the food is received, to be digested for the\nnourishment of the {130} system; and even some of these minute objects\nwhich vary in size from one _two-thousandth_, to one _three-thousandth_ of\na line in diameter, are said to be carnivorous and predacious. Upon this\nfact alone, I would place the improbability of insects being the cause of\nepidemic disease. Each insect doubtless has its own peculiar food, and\nwhether it be a vegetable or animal feeder, it consumes the matter already\norganized for conversion into its own tissue, and the only change which\ncould be affected by them in the blood, would necessarily be that of\nappropriation of some one of the constituents as an element of food; when\nthat food is digested, (taking digestion generally as an identical\nprocess,) the excrementitious matter is composed of secretions and\ndisorganized matter, mixed together as an _effete_ product, and destined\nthen for reorganization by the vegetable kingdom. Now all animals, whether\nthey be large or small, live on organized matter,--they convert that matter\ninto an inorganic form, and I cannot help imagining that if epidemic\ndiseases and fevers depended upon animalcular growth and development in the\nblood or tissues of the body, the excretions or secretions from them would\nhave yielded some information to the searching enquiries of the chemist,\nsupposing that these excretions and secretions were capable of reaching to\na sufficient amount in quantity, to bring about those fatal effects of\npoisoning, we witness in Cholera and other epidemic affections. Insects, I\n{131} believe are poisonous only by their secretions, and though they are\nknown to multiply with exceeding rapidity, I can hardly imagine that by\ntheir development, however rapid, they could produce such a change in the\nhuman body, as to bring about the speedy dissolution, and generally\ngangrenous appearance, that has invariably been observed in those suddenly\ndying under the influence of epidemic poisons. The vibriones, whose\ndestructive effects on wheat are so well known, are a genus of animalcules,\nwhich at first would seem to favour the animalcular theory in a remarkable\nmanner; for on examining them, they do not appear to possess any other\nstructure than a gelatinous absorbing mass, in this respect resembling a\nvegetable.\n\nBut Ehrenberg's scrutiny corrected the error of De Blanville, and shewed,\nthat they were far from being agastria, or stomachless animals. The Rev.\nWilliam Kirby says, \"Ehrenberg has studied the vibriones in almost every\nclimate, and has discovered, by keeping them in coloured waters, that they\nare not the simple animals that Lamarck and others supposed, and that\nalmost all have a mouth and digestive organs, and that numbers of them have\nmany stomachs.\" All the discoveries indeed which have been made on the\nminuter forms of animal life, have tended to confirm the doctrine that the\nstomach is the exponent organ of an animal; that is, in all animals there\nexists, in a variety of modified conditions, a receptacle for food. Some of\nthe {132} animalcules, however, are still supposed to exist by absorption,\nas the vinegar eel, _vibrio anguilla_,[54] but when we find that the law\nis, generally speaking, that the receptacles of food become multiplied in\nnumber in these minute beings, and the vibriones which were supposed to be\nstomachless, have been proved to emulate their associates in the number of\nthese organs; it would be more reasonable to conclude that our imperfect\nvision is the barrier to their detection, rather than to suppose that they\ndo not exist. Besides, when we are told on undoubted authority that some of\nthe animals of this class, have as many as _forty or fifty_ stomachs; the\nleast we can do, is to allow that all of them possess, at least one\ndigestive organ, though we may not be able to detect it.[55]\n\nSo far then for the consideration of animalcular structure: let us now more\nparticularly enquire into their destructive habits, and their functions,\ninasmuch {133} as they may be supposed capable of engendering epidemic\ndiseases and fever. The truly carnivorous animalcules, or those truly\nherbivorous in their instincts, we may presume to be beyond the limits of\nour enquiry. We have rather to do with those which take an intermediate\nposition, namely, those which feed upon matter undergoing decomposition, or\nupon fluids containing organic matters in solution, or suspension. If we\ntake Entozoa generally, they may be considered as most conveniently to be\nplaced in this intermediate class; and here we find still the digestive\napparatus, and more than this,--for upon the modifications of the organs\nappropriated to digestion is their classification founded. \"Rudolphi\ndivided the Entozoa into Sterelmintha, or those in which the nutrient tubes\nwithout anal outlet are simply excavated in the general parenchyma, and\ninto the Coelelmintha, in which an intestinal canal with proper parietes\nfloats in a distinct abdominal cavity, and has a separate outlet for the\nexcrements.\"[56]\n\nHow do these animals obtain their sustenance, and what changes can they\nproduce upon the vital fluid of the body? Analogy is here our only guide.\nIf the trichina spiralis is examined, it is found to be enclosed in a cyst\ncontaining fluid; and this is, {134} doubtless, the source of its\nnutriment, and contains in solution the elements for its nutrition; but in\nthis instance there is no selection, and there can be no locomotion to an\nextent sufficient to imply searching for food, as the animalcule in its\nnatural state, when taken from the human muscle, is found coiled upon\nitself, making about two and a half turns. The fluid of the cyst is thus in\nall likelihood prepared by endosmosis, for the immediate and appropriate\nnutrition of the parasite. The cyst is thus the part which performs the\ndiseased process, the containing animalcule is merely the consumer of what\nis prepared for it by the cyst. And this would seem to be the rule with all\nparasites, of the encysted kind.\n\nWe have alluded to the vibriones which are found in the fluids of living\nbodies, and the trichina which is found in the solid muscle; we have now to\nrefer to those which infest the cavities. It was, I believe, Ehrenberg, who\nshewed that the tartar which accumulates on the teeth is composed of the\ndebris of minute animalcules; in fact, that it consists of calcareous\nmatter, having once formed a portion of the structure of their bodies, the\nubiquity of these creatures is therefore as much and clearly established as\nthe lower forms of vegetation. The intestinal worms, of which perhaps the\nTaenia is the most curious and important to be noticed, are from the\nlocality in which they are found, chiefly injurious by the irritation they\nset up, and by appropriating {135} to themselves the nutrient juices\nelaborated in the process of animal digestion, thus depriving the\nindividuals they infest of that which was destined for their own\nnourishment. In this, as in all associated instances, the character by\nwhich these parasitic animals are marked is their consuming propensity.\nThere is, however, one more observation to make upon parasitic growths; but\nthe question is yet unsettled in what kingdom of nature is the\nacephalocyst, or hydatid, to be placed. Mr. Owen says, \"As the best\nobservers agree in stating, that the acephalocyst is impassive under the\napplication of stimuli of any kind, and manifests no contractile power,\neither partial or general, save such as results from elasticity, in short,\nneither feels nor moves, it cannot, as the animal kingdom is at present\ncharacterized, be referred to that division of organic nature.\"\n\nWe thus arrive at the simple cell, and the multiplication of living beings\nby cell buds; it is the point at which the confines of the animal kingdom\nare reached, and at which we are driven to speculation. The hydatid lives\nlike a plant, by imbibition; and procreates, like a plant, by budding,\neither endogenously or exogenously, as regards the original or parent\ncell.[57]\n\n{136}\n\nThis condition of being, suggested the notion of Protozoa, or first\nanimals, in the same way that the purely cellular plants, that is, each\nindividual, consisting of a single cell, gave the idea of Protophyta, or\nfirst plants. Mr. Kirby thus expresses himself on this subject: \"The first\nplants, and the first animals, are scarcely more than animated molecules,\nand appear analogues of each other; and those above them in each kingdom\nrepresent jointed fibrils.\"\n\nAdmitting, then, that animals as well as plants exist in the form of simple\ncells, and that their multiplication proceeds apparently upon the same\nprinciple in each, it is nevertheless abundantly manifest, that the\ncellular form of perfect individuals is infinitely more numerous in the\nvegetable than in the animal kingdom.\n\n{137}\n\nFrom the mosses downwards to the fungi, the whole structure of the plants\nconsists of an aggregation of cells, more or less in number and complicate\narrangement, until, through a variety of gradations, we reach the single\ncell as a perfect individual.\n\nIt is rather remarkable, that the lower forms of vegetables and animals\nseem to derive their nutriment from matter of a similar kind; and though\nthe office of plants is as a rule, to convert inorganic into organized\nmatter, it appears that some of the fungi may live as animals do on organic\nmatter when in a state of solution. This, however, is uncertain; for we do\nnot know what are the first signs of decomposition in organized bodies, and\nfor aught we can tell, it may be perpetually going on; so far as the\ndisengagement of carbon from the system is concerned, this is certain; but\nwhether the nitrogenous compounds also are subject to a resolution into\ntheir elements in the living body, is another question, and not so easy of\nsolution. The partially decomposed elements of animal structures are,\nhowever, particularly adapted for the nutrition of the lower forms of\nvegetation; it is, indeed, from the decaying organic matters that the fungi\nderive, it may be said, their entire food.\n\n       *       *       *       *       *\n\n{138}\n\nSECTION III.\n\nSKETCH OF THE PHYSIOLOGY AND PATHOLOGY OF PLANTS AND ANIMALS.\n\nAnimals and plants depend for their existence upon a nutritive fluid, which\npermeates their structure; it is the element from which all their\nsecretions are formed, and their organs are nourished.\n\nThe food of animals is composed of previously organized matters, and is\nconveyed into a reservoir called a stomach, where it undergoes a process of\nsolution, previously to entering the circulation. At this period, the\nanimal and the plant again present points of resemblance, the lymphatics or\nabsorbent vessels take up the products of digestion, and convey them to the\nblood-vessels, where mingling with the current of the blood, they are\nconveyed to the lungs, there to undergo a process of oxygenation before\nthey become fitted for the renovation of the tissues of the body. Such is\nthe nature of the food of man, that it contains all the elements necessary\nand adapted for transformation into bone, muscle, brain, and parenchyma, as\nwell as the other tissues of the body; besides other elementary matters,\nwhich, though they form a very insignificant portion of {139} animal\ntextures, from their constant presence in the vital fluid, evidently\nperform some important offices in the general economy of life; they are\npartly, perhaps, occupied in forming constituents of secretions.\n\nPlants do not require a stomach,--the humus or soil to which they are fixed\nis the laboratory, where the nutritive matter is prepared in a state fit\nfor absorption by the spongioles of their roots, and these correspond to\nthe lymphatics of animals; after being taken up by the spongioles, this new\nfluid mingles with the sap, and passes to the leaves or breathing apparatus\nof plants, where carbonic acid gas combines with the crude vital liquid,\nand converts it into a condition fit for all the offices to be performed by\nthe plant: viz. the growth of tissues, and the elaboration of secretions.\n\nThe tissues, however, of plants, though more simple in their nature,\npresent a much more varied character than those of animals, when the\ndifferent species are compared.\n\nThe bones of animals which give them their form, are invariably constituted\nof phosphate and carbonate of lime, deposited in a matrix of gluten;\nmuscle, nerve, brain, tendons, and ligaments, have nearly, if not\ncompletely, an identical composition throughout the whole range of the\nanimal kingdom: their secretions, however, vary much more considerably, as\nalso do the secretions of vegetables. But vegetable tissue may contain, as\nin the stems of {140} grasses, a considerable amount of silex, and some\nnotable quantity of sulphur, and so essential to their existence is the\nformer element, that they cannot live without its presence in the soil, and\nalso with it an alkali, to render it soluble. A large amount of soda, is an\ninvariable attendant upon the structure of marine plants, as potash is of\nthose growing on the land.\n\nThus, whether we regard the health of animals, or vegetables, we discover,\nthat besides the matters which are absolutely indispensable for the\nnutriment of the tissues which undergo rapid transformation, those of a\nmore permanent and durable nature require in an almost insensible degree, a\nrestitution of elements; and though not apparently absolutely necessary to\npreserve vitality in the being, yet have so marked an influence over it, as\nto indicate an extensive bearing of each individual part, on the whole\nassociated entity.\n\nThe elementary tissues of both kingdoms have been traced, in whatever form\nthey may be found, to a cellular origin. The minutest vegetable germ, is a\ncell containing a granular matter within it, and even man himself, in his\nembryonic state, may be represented as an insignificant point in the realms\nof space; and might be placed side by side with the smallest particle of\nliving matter, without suffering by the comparison.\n\nThe laws by which the development of these elementary cells is regulated,\nso that each advances {141} to its limit, and fulfils its destination, is\none of those inscrutable and overwhelming mysteries of nature, which leads\nthe admirer of creation on and on into the abyss of the future, and fills\nhis soul with aspirations for that time, when the veil of ignorance shall\nbe withdrawn. But this is not my subject.\n\nThe organization of the two animated kingdoms, is then regulated by\ndefinite laws, and all matter, whether acting upon them as agents of\nnutrition or destruction, are equally under their dominion; to investigate\nand to endeavour to fathom some of these laws, is the aim I have in view.\n\nThe sap is to the plant, what the blood is to the animal,--the elements of\nnutrition and secretion are contained in it, and whatever interferes with\nits normal constitution by subtracting from, or adding to it, deteriorates\nits qualities, and retards or accelerates the functions of the individual.\nExcess or deficiency of the natural elements may also be a source of\ndisturbance; if carbonic acid be too abundantly liberated in the soil, as\nDr. Lindley expresses it, \"plants become gorged;\" and if, on the other\nhand, the elimination be too slow, they become starved. It has been also\nshewn, that plants though they give out oxygen from their leaves, do not\nthrow it off as animals do carbonic acid from their lungs; but that this\narises as a result of digestion, and the fixation of carbon in the system,\nand that they really respire oxygen as {142} animals do, and give off\ncarbonic acid, both by day and night.\n\nThat light is the stimulant of the digestive functions, and that,\ntherefore, during the day, the amount of oxygen thrown off, far exceeds the\namount of carbonic acid liberated during the same period.\n\nThe great and important distinction between animals and plants is, that the\nformer possess a nervous system, by which they are subject to a very\nextended series of psychological relations; it is in these chiefly, if not\nentirely, that we are to look for the distinctive and well-marked\ndifferences of diseased action. In animals there are special media of\ncommunication between the sources of dynamic power, and the parts upon\nwhich the force is exercised: and again, a return communication exists,\nwhich conveys impressions to the source of power, and to use a simple\ncomparison, a system of telegraphing is in incessant and watchful\noperation. This force is influenced and modified in its action, when\nexercised in the regulation of nutrition, growth, and reproduction of\ntissues, by the passions and emotions of the mind. All the secretions and\nfunctions of the body are more or less susceptible of being accelerated,\nretarded or modified by the psychical relations of mind and matter. Though\nwe are apt to imagine that in man alone, these phenomena obtain much\nimportance--there can be but little doubt, that wherever a {143} nervous\nsystem exists, whether in the form of aggregated or diffused ganglia, the\ninterdependence of force and organization, each upon the other, bears a\ncertain and definite physiological comparison; the more aggregated the\nganglia, the more close, intimate, and extensive the psychical connexions,\nand the gradations pass downwards, until they appear to be lost on the\nconfines of the vegetable kingdom.\n\nThe diseases of plants and animals deserve a more careful comparison than,\nI think, has hitherto been bestowed upon them.[58] If the study of\nphysiology, or an enquiry into the laws which regulate the functions of\nliving beings in a state of health, has been materially aided by the\nintimate knowledge of vegetable physiology, which, from the simple\nstructure of plants, so favours the experiments of the student, there is\nevery reason to suppose that vegetable pathology may also lead us to an\nequally important and useful result.\n\nIt is quite certain, that if a healthy seed, or leaf-bud, be placed in such\na situation, that, according to the laws known, it will in all likelihood\ngerminate, if all the elements for its sustenance exist in the soil, and\nthe temperature and hygrometric {144} condition of the atmosphere are\nadapted to it, a healthy plant will be the result. Light, heat, moisture,\nand soil are therefore to be considered as the agents required to exist in\na certain balance, or proportion, in reference to the health or power of\nvitality of the plant. Within a certain amount of variation, health may\npersist in virtue of the power of selection, which appertains to the\nspongioles of the root in absorbing nutriment; and also as regards light,\nfrom the tendency which most plants have to accommodate themselves to any\ndeficiency of this element, by presenting their leafy expansion in that\ndirection where the most of its influence may be obtained. But beyond a\ncertain limit an unhealthy condition sets in. If the soil contain not the\ninorganic elements, which are absolutely indispensable for the tissues of\nthe plant, or even if they be there and not in a state to be absorbed, a\ndwindling and degeneration ensue; if light be deficient in quantity,\npallor, feebleness, and elongation of tissue follow, with more fluidity and\ngeneral softness of texture. These conditions of plants have their\nanalogues in the ill-fed and ill-nourished children in some of our\nmanufacturing districts; they are stunted and diseased. Transport a healthy\ncountry lad, with the bloom of health on his cheek, from his native hills\nand valleys, or woods and fields, to the stool behind a desk for eight\nhours a day, in a narrow street in any city, where the rays of the sun\nrarely penetrate, it will not be long before {145} the skin of the animal\nand the cuticle of the plant may be submitted for comparison, when both\nwill testify to the importance of the solar rays, as an indispensable agent\nin supporting the normal processes of organic life. So far common\nobservation is competent to a solution of the facts; but beyond this we\ncome to the enquiry, what resemblances are there in the early conditions of\nplants and animals. Each originates from nucleated cells, endowed by the\nAll-seeing Power with a blind impulse of progressive development; the most\nsimple cell of a vegetable multiplies itself by a generation of new cells\nwithin it, when the parent dies, and liberates the offspring. Here\nprogression is simply multiplication; it is, as it were, progression in\nlength only. The original cell, however, of animals, which is styled the\ngerminal vesicle, extends or becomes developed into dissimilar parts; and\nwhatever may be the variety, all alike proceed from the original germ cell,\nand the _tout ensemble_ of parts constitutes the one and indivisible whole;\nin this instance there is addition besides multiplication, tissues and\norgans are added in all variety, until the maximum of organic development\nis attained in the wonderful being, man.\n\nYet how many points of resemblance are there between the vegetable cell and\nthe fully developed human being, in a physiological and pathological point\nof view. There must be nourishment to sustain both; both require a certain\namount of light {146} and heat for their growth and increase, and are\ndependent upon various unknown causes for active and healthy existence; and\nwhen a certain time has expired, all alike return to a condition, in which\nthe particles composing them are subject only to the dominion of the laws\nwhich preside over inorganic matter.\n\nBut during the existence of plants and animals, we discover other features\nof comparison; plants, as well as animals, are liable to disease; they are\nsubject to functional and organic affections. The former, among plants, are\nusually traceable to atmospheric vicissitudes or irregularities, changes of\nsituation, &c.; and in man to irregularities of diet, and mental and bodily\nexcesses, as well as to atmospheric vicissitudes.[59]\n\nThe organic diseases of plants and animals depend upon a repetition, or\ncontinuance, of functional derangement. As a consequence of this, the\nnutrition and reproduction of tissues lose their normal and definite\ncharacter, wherefrom an indefinite and abnormal result is obtained. There\nis a limit to abnormal productions, and they are apparently {147} subject\nto laws, though not yet understood. In animals, they may be either\nexcessive development of natural tissue in natural localities, as obesity\nand fatty tumours; they may be natural products in unnatural situations, as\nfatty degenerations of muscular tissue; or altogether new and unnatural\nproducts, as tubercle and cancer.\n\nIn plants, from their greater simplicity of structure, organic affections\nare perhaps entirely limited to the two first forms of animal organic\ndisease; viz. to undue development of tissue in natural situations, and to\nthe formation of natural tissue in parts of a plant where they are not\nusually found in a state of nature. The variety of excrescences seen on the\nstems, branches, and twigs of plants, may be given as instances of the\nformer; and the conversion of stamina into petals, as in double flowers, as\nan instance of the latter.\n\nWe derive our sustenance from vegetables, and they from us; they produce\nfor us the soothing opiate and the deadly strychnia; we for them the\nanimating ammonia, and the distortions and sterility of excessive culture;\nwe engender in them, by the latter, debility, disease, and death; and in\nour turn we become their prey. All this indeed is but a cycle of events,\nthat requires no learned mind to fathom, and to comprehend; it is a matter\nof every day occurrence, and, though perhaps not entirely unheeded, is not\ndwelt upon in the fulness of its bearings and importance. {148}\n\nLet us now consider the diseases of plants, as a study progressive to those\nof man; and as their physiology has so extensively served us, we may\npossibly also find in their pathology much material for instruction; not\nthat it will be attempted to shew that the same diseases affect both\nkingdoms, but that diseases, though dissimilar in effects, may have similar\nsources.\n\nUnfortunately, there are not many men in this country, who need go further\nthan their own gardens to find abundance of disease among their fruit trees\nand vegetables. The vine, the apple and the potato, common to most gardens,\nwill furnish specimens.\n\nIt is an error of a serious kind to suppose, that the parasites which\ninfest plants are not essentially the cause, or, perhaps, more properly\nspeaking, the elements of disease. I confine myself here to disease of\nparasitic origin, as that is the subject of which I am chiefly treating.\n\nThat parasitic growths are the elements of disease in some instances, is\nnow beyond dispute. The experiments of Mr. Hassall, detailed in Part II. of\nthe Transactions of the Microscopical Society of London, are most\nconclusive; and they are of that simple nature, that any one may convince\nhimself of their accuracy, by a repetition of them from the directions\nthere laid down.\n\nHe says, the decay is communicable at will \"to any fruits of the apple and\npeach kind, no matter {149} how strong their vital energies may be, by the\nsimple act of inoculation of the sound fruit with a portion of decayed\nmatter, containing filaments of the fungi. We may use with success the\nsporules of such fungi; but in this case the decomposition does not set in\nso quickly; in the one case, the smaller filaments of the fungi have\nadvanced several stages in their growth; while in the other, the sporules\nhave yet to pass through the several stages of their development.\"\n\nMr. Hassan, however, seems to speak doubtfully as to the mode in which the\ndisease becomes naturally introduced;[60] how the spores enter the fruit,\n\"is not very clear--though probably, it is by insinuating themselves\nbetween the cells of which the cuticle is composed, or perhaps by means of\nthe stomata, where they are present. I may here state that the experiments\nwere made on fruit, while living, and attached to the tree.\"\n\nBut why should there be a doubt as to the parts by which the sporules of\nminute fungi enter the plant, when it is clear, that not only can they\nenter {150} by the spongioles, but by the stomata of the leaves, and mingle\nwith the sap. It is true, that they make their appearance and grow upon the\nleaves and the fruit; but these are the situations most adapted for their\nfructification. I have seen the spores of the fungi which attack the\ncucumber and vegetable-marrow, in the cells of the hairs, and even their\nfilamentous prolongations; these appropriate the fluids conveyed to the\ncells of the hair, rupture them, and at length fructify.\n\nOn referring to Dr. Lindley's Medical and Economic Botany, I find that many\nfungi are the active elements of disease, and in a manner which renders it\nhighly improbable that they are so in any other way, than by obtaining an\nentrance to the sap of the plants. Of the microscopic fungus which destroys\nwheat, the Uredo caries of De Candolle, we find the habitat to be within\nthe ovary of the corn, and that 4,000,000 may be contained in a grain of\nwheat,--now this and another fungus, the Lanosa nivalis, are said to\ndestroy whole crops of corn: we cannot imagine that such an extensive\naffection, can have any other source than by means of the spores through\nthe sap, seeing that bruising of the surface, or rupture of the cuticle of\nthe apple, a comparatively soft fruit is necessary to produce the disease\nartificially in them; besides, a grain of corn containing vibriones, when\ngrown and having fruited, the new fruit also contains them--now here, as\nthis is I believe almost invariably the {151} case, either they or their\nova must be carried with the sap to the new germs.\n\nIt is rather a remarkable fact, that these entophytes appropriate the\nnutriment destined for the plant in which they grow, they are consequently\nthe means in many instances of its entire destruction, though only\npartially so in others.\n\nThere are many Fungi which have this tendency. The Puccinia gramienis,\n\"preys upon the juices of plants, and prevents the grain from swelling.\"\nThe Aecidium urticae, common on nettles, deprives the plant on which it\ngrows, of the organizable matter, intended for its own nutrition. The\nErysiphe communis, overruns and destroys peas. The Botrytis infestans,\n\"attacks the leaves and stems of potatoes.\" The Oidium abortifaciens,\nattacks the ovaries of grasses--and the Oidium Tuckeri, \"a formidable\nparasite, destroys the functions of the skin, of the parts it attacks.\" The\nlatter has been most injurious to the vines, during the last two years. I\nhave known instances in which the vines have been cut down, and every means\ntaken to rid the houses of the disease; but this year, it has made its\nappearance, with all its former virulence, in the new shoots.\n\nThis, however, is sufficient to shew that plants are liable to disease,\ndepending upon parasitic growths, which affect their vital powers, and\ndeprive them of their natural nutritive fluids.\n\nBut somewhat similar diseases belong also to {152} warm climates; in a\nletter from Cuba, dated Dec. 1843,--Mr. Bastian writes, \"_a plague_ has\nappeared among the orange trees--a mildew attacking the leaves and the\nblossoms, which finally dry up. It most frequently kills the trees. None of\nthe orange family are exempt; lemons, limes, and their varieties, with the\nshaddock and forbidden fruit, have all suffered.\" This disease has\ncontinued without intermission, till the present year,--when the same\ngentleman writes, Feb. 20th, 1850: \"The evil exists, although in a\ndiminished degree, so much so, as to have allowed the trees to produce me\n30,000 oranges again. In old times, the same plantations produced me\n100,000.\"\n\nThe West India sugar-canes are also liable to a disease, which the Rev. Mr.\nGriffiths, in his Natural History of the Island of Barbadoes, speaks of, in\nthe following manner: \"This, among diseases peculiar to canes, as among\nthose which happen to men, too justly claims the horrible precedence.\" This\ndisease is called the Yellow Blast. It is difficult to distinguish the\nBlast in its infancy, from the effect of dry weather.\n\nThere are often seen on such sickly canes, many small protuberant knobs, of\na soft downy substance. It is likewise observable, that such blades will be\nfull of brownish decaying spots. The disease is very destructive to the\ncanes. It is observed, that the Blast usually appears successively in the\nsame fields, and often in the very same spot of land. {153}\n\nThis Blast is often found far from \"infected places,\" and the infection\nalways spreads faster to the leeward, or with the wind.\n\n\"_It is remarkable if canes_ have been once infected with the Blast,\nalthough they afterwards to all appearance, seem to recover; yet the juice\nof such canes will neither afford so much sugar, nor so good of its kind,\nas if obtained from canes which were never infected.\"\n\nI may here allude to the circumstance, that in the island of Cuba, the\ndestructive mildew is commonly called, _la pesta_.\n\nIt were needless to multiply instances of other endemic and epidemic\ndiseases of vegetables; they are well known by practical observers to be\nvery numerous, and I believe, in most instances, depending upon fungoid\ngrowths. The destruction of vegetables by insects, is of a very different\nnature to that produced by the fungi; it would be as unreasonable to\nconsider the consumption of corn and herbage by locusts, as a disease of\nvegetation, as the massacre and devouring of human beings by cannibals, a\ndisease of the human body.\n\nIt is true that insects are exceedingly destructive to plants, but as far\nas I am able to obtain information, they appear to be so chiefly by their\nvoracious propensities; they consume the structure of the plant in its\nentity, and do not primarily interfere with its vitality. The instance of\nthe vibriones, before-mentioned, seems at first to be an exception {154} to\nthe rule, but this is rather apparent, than real; and it may be made to\napply more as a confirmation, than an obstacle to the vegetable theory: for\nif we may fairly compare the diseases of animals with those of plants, the\nexistence of entozoa in the latter, would be considered an essential point\nto be substantiated.\n\nHaving now considered the question as to the infeasibility of supposing\nthat chemical fermentation is the basis upon which a theory of diseases can\nbe sustained, and having shewn that life is inseparable from infection, and\nmiasmatic generation;--having explained the phenomena of the dispersion of\ndiseases by comparison with the dispersion of plants, and finally, having\ndemonstrated that the physiology and pathology of plants bear so close a\nrelation to each other, and that their epidemic affections depend upon\nminute organic germs, I submit to the judgment of my readers, whether there\nis not much reasonableness in the application of the facts to the\ninference--that living germs are the cause of epidemic disease in man and\nanimals.\n\n       *       *       *       *       *\n\n\n{155}\n\nCHAPTER IV.\n\nRESULTS IN PROOF OF THE TENABLENESS OF THE PROPOSITION.\n\n--------\n\nSECTION I.\n\nOBSERVATIONS ON SOME OF THE LAWS OF EPIDEMIC DISEASES.\n\nThe results obtained by comparing certain facts connected with Epidemic\nAffections of animals, with analogous affections in plants, afford, from\nthe few instances I shall here notice, a very strong presumption, that\nanalogous causes operate in the production of these affections. I have\nalready quoted from Hecker, to shew that previously to, and during the\nEpidemics of the Middle Ages, the minuter forms of animal and vegetable\nlife appeared to be called into existence, much more abundantly than usual;\nthat famines prevailed in consequence of failure of cereal crops, no doubt\ndepending then, as now, upon the various forms of fungiferous growth. I\ncannot refrain quoting here, a passage or two from our old friend Virgil;\nfor he confirms not only the fact of peculiar showers in {156} connexion\nwith diseases, but he also refers to the rust of corn, thus:\n\n  150. \"Mox et frumentis labor additus; ut mala culmos\n  Esset rubigo ...\n  ... Intereunt segetes.\"\n\n  _Georg. 1._\n\nThen:\n\n  311. \"Quid tempestates autumni et sidera dicam?\n\n    .    .    .    .    .    .\n\n  322. \"Saepe etiam[61] immensum coelo venit agmen aquarum\n  Et foedam glomerant tempestatem imbribus atris\n  Collectae ex alto nubes.\"\n\n  _Georg. 1._\n\nThe occurrence of black showers in this country has been observed during\nthe present year, and I understand that in the fenny countries of the East,\nthe corn has suffered much from the Uredo. I am not mentioning the\ncircumstances as cause and effect, but merely to call attention to the\nfact, that unusual phenomena of this kind have been generally associated\nwith disease of the animal and vegetable tribes.\n\nThe same causes also predispose plants as well as animals, to epidemic\nattacks of disease. The repeated observations in the public journals on the\nsubject of ventilation, drainage, and over-crowding, render all notice from\nme needless, to shew that these, though they do not produce the diseases\n{157} treated of, yet that under the influence of bad air, bad drainage,\nand over-crowding, epidemics are fostered and spread.\n\nLastly, says the Count Philippo R['e], \"I would remark that if _bad\ncultivation, and especially bad drainage, does not produce bunt or smut, it\nis certain that those fields, the worst treated in these respects, suffer\nthe most from these diseases_.\"\n\nIt has been remarked by many observers, that a greater fecundity has\nattended upon Pestilences, and this has been proved by comparison, that the\nbirths in proportion have far exceeded the ordinary limit.[62] In\njuxtaposition with this observation, I will place the following, not as a\nproof, but as a remark made quite independently of the subject of which I\nam treating. \"From the first the diseased ears are larger than the healthy\nones, and are sooner matured. What appears singular, but which I have not,\nperhaps, sufficiently verified, is _that the seeds are more abundant than\nin a sound ear_.\"\n\n{158}\n\nNow these are facts which require amplification, and if these two alone\nshould be shewn upon an extensive field of observation, to apply not only\nto corn, but to other members of the vegetable kingdom, as I doubt not will\nbe the case, though I am not fully prepared to prove it, it would be\ndifficult to dissociate the fertility of the two living kingdoms from the\noperations of one and the same, or an analogous law.\n\nThe epidemic diseases of plants are both infectious and contagious, at\ntimes they are observed to be endemic only, and then depending particularly\nupon some local causes. This is a law of diseases which applies equally to\nthose of men and animals. In connexion with this law is another, which, as\nfar as I am aware, has not hitherto been noticed in connexion with plants.\nThe potato disease, which excited so much interest and created so much\nanxiety for the poorer classes of society, led the Government of this\ncountry to employ the most learned men to investigate the subject, in the\nhope of propounding some reasons which should explain the cause of the\ncalamity, and thereby deduce a method of eradicating the evil, or, in other\nwords, discover a cure for the disease. Many were the opinions as to the\ncause of the distemper, which it were useless here to recount, but a method\nwas suggested, to which most people, I believe, looked forward with great\nanticipations, and this was to obtain native seed, and to sow it on virgin\nsoil. Was the end accomplished? No. {159} For though the seed was sown, and\nthe plants grew, the disease still appeared among the newly imported\nindividuals, to as great an extent, as among the native or domesticated\nplants.\n\nAs a parallel to this, it may be stated, that, as regards either endemic or\nepidemic disease, those persons newly arrived, either in a district or\ncountry where these prevail, are even more liable to them than the\nresidents.[63] Again, I have learned, that where the potato disease has\nbeen so bad as to render the crop almost valueless, the best plan to be\nadopted is, to allow the plants to remain in the earth, and thus leave such\nas retain their germinating powers to come up spontaneously the following\nyear. I certainly saw one large field treated in this way, yield a crop\nalmost without disease.\n\n{160}\n\nThe seasoning, in this instance, seems to bear a comparison with the\nseasoning of animals and man, under a variety of diseases, which for a time\nrenders them insusceptible of another attack. It therefore does not appear\nso improbable, that these affections may be regarded, as Unger, the German\nbotanist supposed, the Exanthemata, or Eruptive Fevers of vegetables.\n\nAnother feature seems to associate the Epidemics of plants and animals, in\na manner suggestive of analogous causes operating in both instances.\n\nThe lungs of animals and the leaves of vegetables, are their respiratory\norgans, by means of which, the blood in the one case and the sap in the\nother, derive gas from the air, and impart gas to it, each taking what is\nthrown off by the other.\n\nNow the epidemics among vegetables, have a remarkable tendency to exhibit\ntheir effects primarily on the leaves, and particularly on those parts\nwhich are appropriated to the function of respiration. It is from the\nstomates that many of the fungi commence to germinate, and their\nfructification may be seen sprouting from the opening composed of a chink,\nsurrounded by a peculiar arrangement of cells, which constitute the\nbreathing apparatus of their victim.\n\nIn the earlier epidemics, of which we read, one of the most remarkable\ncircumstances, was the extraordinary influence the poisonous matter\nappeared to {161} exercise over the lungs,[64] and they again, were the\nmeans of propagating the disease, and spreading the contagious particles\nthrough the atmosphere, for we read: \"Thus did the plague rage in Avignon\nfor six or eight weeks, and the pestilential breath of the sick, who\nexpectorated blood, caused a terrible contagion far and near, for even the\nvicinity of those who had fallen ill of plague was certain death; so that\nparents abandoned their infected children, and all the ties of kindred were\ndissolved.\"[65] \"The like was seen in Egypt. Here also inflammation of the\nlungs was predominant.\" \"Here too the _breath_ of the sick spread a deadly\ncontagion.\"\n\nIt is more than probable that all infectious matter obtains an entrance to\nthe system through the lungs. Inspiring the air containing the pestilential\nsemina is, indeed, the only plausible explanation of infection; for though\nthe skin is indubitably an absorbing {162} surface, and capable of taking\nup and conveying to the blood any noxious matter applied to it, yet it is\nfar more probable that the lungs would effect this process with greater\nrapidity. Then the stomach, the only other absorbing surface to which\nextraneous matter can be applied, is not likely to be the part where the\nelements of disease would obtain an entrance to the system, for many facts\nprove, that infectious matter may be swallowed without any injurious\nconsequences, unless in a very concentrated state. Instances are not easily\nfound of diseased matter having been swallowed, except where diseased\nvegetables have formed under some combination of circumstances, a portion\nof diet.[66]\n\nMany facts are on record which prove the powerful effect of diseased grain\nwhen made into bread, and taken for any length time as a principal article\nof food. The history of Ergot of Rye is too fresh in the memory of most\npeople to require more than an allusion here. The stomach had no power over\nthe secale, its poisonous properties were retained, after having been\nsubmitted to the digestive process, as was evidenced by the abortions and\ngangrenes it occasioned.\n\nBut diseased wheat is also capable of inducing {163} gangrene, and it is\nmore than probable, that many diseases might be traced to the use of\ninfected grain of various kinds. An interesting account of a family who\nlived at Wattisham, near Stowmarket, in Suffolk, and all of whom suffered\nmore or less from living on bread made of smutty wheat, may be found in the\nPhilosophical Transactions. The mother of this family and five of the\nchildren, consisting of three girls and two boys, all suffered from\ngangrene of the extremities; the father lost the nails from his hands, and\nhad ulceration of two of his fingers.[67] Dr. Woollaston wrote thus in a\nletter on this case: \"The corn with which they made their bread was\ncertainly very bad: it was wheat that had been cut in a rainy season, and\nhad lain on the ground till many of the grains were black and totally\ndecayed, but many other poor families in the same village made use of the\nsame corn without receiving any injury from it. One man lost the use of his\narm for some time, and still imagines himself that he was afflicted with\nthe same disorder as Downing's family.\" It is not unlikely this was the\ncase, for numbness and loss of power was one of the well marked characters\nof the disease.\n\nWhat other afflictions may be due to diseased vegetation and adulterated\narticles of food, and what loss of life may accrue from cheap and\nadulterated {164} drugs and chemicals is hardly yet dreamt of.[68] The\nsystematic practice of adulteration of almost every article of diet which\ncomes to table has become a serious question for the legislature to\nconsider. Take only the article of milk, upon which the young children of\nlarge towns and cities, make their chief meals, with the addition of bread.\nHow much milk comes into London from the country, how much is obtained from\nstall and grain-fed cows in the metropolis, and how much is said to be\nconsumed, would be an interesting calculation. It is pretty well known that\na mixture is sold by which a retailer of milk may increase his supply by\none-third or one-half. It was discovered in Paris that the brains of\nanimals, when prepared in a particular manner, formed, when mixed with a\ncertain proportion of milk and water, a very fine and deceptive cream; in\nthat city this system was carried on to a considerable extent. I could not\nhelp alluding to these facts while speaking of diseased grain, for who\nshall say to what extent a miller in a large way of business, may be able\nto \"work in,\" as it is called, a considerable amount of smutty corn in the\nmanufacture of flour? Now, as diseased grain is known {165} to induce\nabortion, it is impossible to tell how small a portion may in some cases\nproduce the effect; we may therefore say with Thomas of Malmesbury, \"There\nis no action of man in this life which is not the beginning of so long a\nchain of consequences, as that no human providence is high enough to give\nus a prospect to the end.\"[69]\n\nTo return,--associated with these observations are other facts of\nconsiderable weight. Before and during pestilences, abortions are more\nfrequent than in ordinary times; infectious and contagious diseases induce\nabortion; besides this, and independently of disease, conditions of the\natmosphere have been known to exist when abortion has been an epidemic\naffection; of this Dr. Copland says, \"to certain states of the atmosphere\nonly can be attributed those frequent abortions sometimes observed which\nhave even assumed an epidemic form, and of which Hippocrates, Fischer,\nTessier, Desormeaux, and others have made mention.\" With this reference I\nwill close the subject of comparison between the affections of the\nbreathing apparatus in animals and plants, merely alluding to the\nprobability that under some conditions of atmosphere, independently of\nheat, &c. vegetables without any other assignable cause will become\nabortive.\n\n       *       *       *       *       *\n\n{166}\n\nSECTION II.\n\nWHAT IS THE NATURE OF THOSE POISONS WHICH MOST RESEMBLE THE MORBID POISONS\nIN THEIR EFFECTS ON THE BODY?\n\nIn the early part of this book, I considered the nature of poisons\ngenerally, and had occasion to remark upon the characters which separated\npoisons into two distinct classes. 1st, Those which have the power of self\nmultiplication; and 2nd, Those destitute of this property.\n\nOf the first we have seen that the poisons of epidemic diseases multiply\nboth in and out of the body.\n\nThe poisons of infectious diseases, not usually epidemic, do the same.\nThose of endemic affections, such as ague and some fevers, usually become\nmultiplied out of the body only, but under some circumstances, and peculiar\natmospheric conditions, they may be also multiplied within the body. The\namount of these poisons necessary to produce their specific effects, may be\ninappreciable. Of the second class, there are two kinds, those derived from\nthe organic kingdom and those derived from the inorganic kingdom. Of these,\nthe amount necessary to produce their specific effects is appreciable and\npretty well known.\n\nBut among those poisons, consisting of organic {167} products, there is one\nwhich seems to hold an intermediate place. This is derived from one of the\nFungals, and as it takes this remarkable position as a link of connexion\nbetween the two classes of poisons, I may be excused quoting a passage of\nsome length upon this agent, from Dr. Lindley's Vegetable Kingdom. \"One of\nthe most poisonous of our fungi, is the Amanita muscaria, so called from\nits power of killing flies, when steeped in milk. Even this is eaten in\nKamchatka, with no other than intoxicating effects, according to the\nfollowing account by Langsdorf, as translated by Greville. This variety of\nAmanita muscaria, is used by the inhabitants of the north-eastern parts of\nAsia in the same manner as wine, brandy, arrack, opium, &c. is by other\nnations.\"--\"The most singular effect of the amanita is the influence it\npossesses over the urine. It is said, that from time immemorial, the\ninhabitants have known that the fungus imparts an intoxicating quality to\nthat secretion, which _continues for a considerable time after taking it_.\nFor instance, a man moderately intoxicated to-day, will by the next morning\nhave slept himself sober, but (as is the custom) by taking a teacup of his\nurine, he will be _more powerfully intoxicated_ than he was the preceding\nday. It is, therefore, not uncommon for confirmed drunkards to preserve\ntheir urine, as a precious liquor against a scarcity of the fungus. The\nintoxicating property of the urine _is capable of_ {168} _being\npropagated_; for every one who partakes of it has his urine similarly\naffected. Thus with a very few amanitae, a party of drunkards may keep up\ntheir debauch for a week.\"\n\nThis property of the amanita, at once places it in a separate category from\nall other organic poisons, it has yet to be shewn upon what this\nintoxicating fungus depends for its activity. Whether some secretion is\nformed in the tissue of the plant, or whether some new arrangement of the\nparticles of matter or modification of the sporules, is brought about by\nentering the system, it is impossible to say. Langsdorf states that the\nsmall deep-coloured specimens of amanita, and thickly covered with warts,\nare said to be more powerful than those of a larger size and paler colour.\nAs the effect is not produced until from one to two hours after swallowing\nthe bolus, and as a pleasant intoxication may be obtained by this agent for\na whole day, and from one dose only, there is a defined line between this\nand the ordinary narcotics and stimulants in common use. That the digestive\npowers of the stomach have no influence over the intoxicating properties of\nthe plant, is manifested in the fact, that the active principle passes into\nthe urine, not only not deteriorated but apparently increased, for, as we\nhave seen, a teacup of the urine from a man, intoxicated by taking the\namanita into his stomach, will cause him to be more powerfully intoxicated\nthan by the {169} original dose. We have, therefore, but two conjectures\nleft for consideration, either the original intoxicating principle is\nexcreted from the system in a condensed form, in which case its\nindestructibility by digestion, makes it approach the ordinary organic\npoisons, or there must be an increase of the toxic agent, in which case we\nmust suppose a reproductive process having taken place in the system.\n\"There is,\" says Dr. Mitchell, \"in the wild regions of our western country,\na disease called the _milk sickness_, the _trembles_, the _tires_, the\n_slows_, the _stiff-joints_, the _puking fever_, _&c._\" The animals\naffected with this disease, \"stray irregularly, apparently without motive;\"\nthey lose their power of attention, and finally tremble, stagger, and die.\n\"When other animals--men, dogs, cats, poultry, crows, buzzards, and hogs,\ndrink the milk or eat the flesh of a diseased cow, they suffer in a\nsomewhat similar manner.\" This disease is attributed by Dr. Mitchell to the\nanimals having grazed on pasture contaminated with mildew, and the\nresemblance to the effects of the amanita, together with the persistence of\nthe specific principle within the fluids and tissues of the body, render it\nmore than probable that to some fungoid growth, is due the peculiar toxic\neffects here noticed. Further: \"The animals made sick by the beef of the\nfirst one, have been in their turn the cause of a like affection in others;\nso that three or four have thus fallen victims successively.\" De Graaf\nstates, that butter {170} made from the milk of diseased cows, though\nheated until it caught fire, did not lose its deleterious properties. The\nurine of diseased animals, collected and reduced by evaporation, produced\nthe characteristic symptoms. All these facts point to some peculiarity in\nthe properties of matter not yet investigated or at least not explained. If\nwe may assume that reproduction is here an element of the persistence and\napparent multiplication of active matter, I know only of one instance to\ncompare with it. A gentleman about to deliver a lecture on the properties\nof arsenic, and its history generally, made two solutions of a given\nquantity of arsenious acid, in the following manner. He took a certain\namount of distilled water, and the same of filtered Thames water, and made\nhis solutions of arsenic by separate boilings, he then as soon as possible\nplaced the liquids in identical bottles, carefully prepared for their\nreception. In the one which contained the arsenic boiled in river water,\nthe hygrocrocis is now growing, while that boiled in distilled water\nremains perfectly limpid and free from any vegetable production. There can\nscarcely be a doubt, that the filtration of river water was not\nsufficiently purifying to remove the minute spores of some lower forms of\nvegetation, which not only live in arsenic but have resisted the\ntemperature employed in boiling an arsenical solution to saturation.\n\nAs to the first class, or truly reproductive and {171} morbid poisons, the\nmost heterogenous ideas have from all time existed. I have introduced the\nnotice of the above poisons, viz. the Amanita, and that which engenders the\nmilk sickness, to compare the results of the morbid poisons on the human\nbody with them, and also to associate them with the effects of diseased\ngrain. From the Amanita and that other fungoid matter which is said to\nproduce the milk sickness, there appears to be a purely toxic action on the\nsystem, but in the instance of diseased grain, a blood disease, ending in\ngangrene, or a specific and peculiar action of the generative organs is the\nconsequence, and where the latter occurs, the poison usually expends itself\non these parts, either by inducing abortion, or augmenting the catamenial\nsecretion.\n\nNow, the morbid poisons, if studied only in their results, shew that there\nis a combination of these two actions. There is usually, in the first\nplace, a toxic or poisonous action, and secondly, a deteriorating or\ndecomposing action on the blood, by which there is a tendency to low or\nasthenic inflammation and gangrene. It matters not what form of fever we\ntake as an illustration, whether intermittent, pestilential, or\nexanthematous, either will serve the purpose of shewing how completely the\neffects of vegetable organic poisons resemble those which for the sake of\ndistinction (I suppose) have been denominated Morbid Poisons.\n\nTake an attack from the paludal poison. It is {172} usually ushered in with\nhead-ache, weariness, pains in the limbs, and thirst, with other symptoms;\nall these are indicative of a poisonous agent in the blood: then come the\nfull phenomena of the disease at a longer or shorter interval, and tending\nultimately to destroy some organ of the body. The mind suffers during the\ncourse of the attack, and delirium occasionally happens. In severe cases of\nthis disease, which were more frequent formerly than now, coma, delirium,\nand frenzy were observed at the commencement of the attack, and a tendency\nto rapid disorganization of one or several of the viscera.\n\nIf we take the effects of poison of Erysipelas, of Scarlet Fever, or\nPlague, in each we find at the onset more or less general derangement of\nthe system, usually with cerebral disturbance and disordered action of all\nthe dynamic forces of the body, which clearly indicate the action of a\npoison; then, unless some favourable symptoms arise, the blood exhibits a\nsteady advance towards disorganization, and sphacelation of one or more\ntissues or parts of the body ensues. In Erysipelas the force of the\ndiseased action is expended on the skin, and subcutaneous cellular tissue;\nin Scarlet Fever the fauces ulcerate, and slough and the parotids\nsuppurate; in the Plague there is a general tendency to putrefaction, and\nthe formation of glandular abscesses with sphacelas. Without going any\nfurther into this matter, for my present intention is merely to draw {173}\nnotice to certain facts, let me now ask, whether or not, do the poisons of\nthe Ergot, the Uredo, and the Amanita, exhibit more analogy in their action\non the nervous system, the blood and the tissues, than any other poisonous\nagents with which we are acquainted? If the whole range of the lower fungi\ncould be examined in reference to their operation on the blood, as\ndecomposers of organic compounds,--if experiments could be made, by which\nthe properties of fungoid matter could be detected, I would venture to say\nthe whole of the phenomena of these diseases could be readily comprehended\nand their intricacies unravelled.\n\nWe know that the fungi are poisonous, that at times and seasons, and under\nvariations of climate, they vary in their effects, and perhaps lose\naltogether these properties. We know that the fungi produce gangrene of the\ntissues, and disorganization of the blood; we know that their spores\npervade the atmosphere, and are ready, under favouring conditions, to\nincrease and multiply; we know that they are ubiquitous, and that those\nconditions most favourable to their development, are exactly such as are\nproved to foster and engender disease, and above all, they have been proved\nto be the elements of some diseases in man, in animals, and in plants. Can\nas much be said of any other known agents, animate or inanimate, comprised\nin our category?\n\nIt has been said, we do not see after death,--the {174} interlacing\nmycilium, or the sprouting pileus; therefore the fungi are not the agents\nof disease--it has been said that carbonic acid and alcohol are not found\nas products of diseased action--consequently disease is not a fermentative\nprocess. \"In all cases,\" says Liebig, \"where the strictest investigation\nhas failed to demonstrate the presence of organic beings in the contagion\nof a miasm, or contagious disease, the hypothesis that such beings have\ncooperated, or do cooperate in the morbid process, must be rejected as\ntotally void of foundation and support.\" Much as I admire the genius of\nthis great man, it is difficult to refrain from remarking, that I doubt if\nany of his great discoveries would have been made, if, in the first\ninstance, hypotheses had not formed the basis of all his researches. It has\nbeen said, \"that casual conjunctions in chemistry, gave us most of our\nvaluable discoveries:\" and it is from casual conjunctions that hypotheses\nare usually formed, the working out proves either their fallacy or their\ntruth, but to say that an hypothesis has no foundation, until demonstrated\nto be true, is rather knocking down argument. And who, let me ask, has been\nmore prolific of hypotheses than our continental neighbour? Yet he,\naccording to his mode of reasoning, would sweep away all such words from\nthe vocabularies of philosophers. What foundation has the chemical\nhypothesis of disease, when it fails to explain the most important element\n{175} of contagious and infectious diseases: viz. the reproductive property\nof their germs?\n\nIt is perhaps necessary to say something in explanation of the sudden\ndeaths arising from morbid poisons. They may occur from two causes. One\nbeing the result of a concentrated amount of poison germs being inhaled\ninto the lungs, and acting as an ordinary toxic agent; and the other, which\nI put only hypothetically, the consequence of the rapid evolution of gas in\nthe vessels arising from a sudden decomposition of blood, as it passes\nthrough the lungs. The only authority I have for this supposition, is the\nfact that the blood after death, from pestilential affections, is found to\nbe far advanced towards decomposition; that in Paris last year, two\npatients were bled while suffering from Cholera, and with the small\nquantity of blood which flowed, bubbles of air also escaped:[70] and\nbesides this, it was demonstrated by Mr. Herapath, that ammonia was given\noff from Cholera patients, both by the lungs and skin. These facts, though\nthey are not conclusive, nevertheless render it probable that such an\nexplanation is not entirely out of reason--especially too, when we know how\nfatal are the effects of uncombined air, when it enters the vessels near to\nthe heart.\n\n       *       *       *       *       *\n\n{176}\n\nSECTION III.\n\nWHAT RESULTS DO WE OBTAIN FROM THE EFFECTS OF REMEDIAL AGENTS, IN PROOF OF\nTHE HYPOTHESIS?\n\nI have here used the word hypothesis, because, having so far advanced in\nthe enquiry, I trust sufficient has been said to render the term\napplicable.\n\nUnder the term remedial agents, I shall include all those causes, whether\nnatural or artificial, which tend to neutralize or destroy the germs of\ninfection, or miasmatic poison, whether this be effected out of or within\nthe body.\n\nFirst, then, let us consider the results of drainage and cultivation in\nremoving the causes of endemic disease. One well authenticated case is as\ngood as a thousand. I will take one, which, from its source, will be\nreceived as unexceptionable; and from its association with a very learned\nand amusing book, will be accepted as an agreeable reminder of the many\npleasant hours spent in the perusal of the poet Southey's \"Doctor.\"\n\n\"Doncaster is built upon a peninsula, or ridge of land, about a mile\nacross, having a gentle slope from east to west, and bounded on the west by\nthe river; this ridge is composed of three strata; to wit, of the alluvial\nsoil deposited by the river in former {177} ages, and of limestone on the\nnorth and west; and of sandstone to the south and east. To the south of\nthis neck of land, lies a tract called Potteric Carr, which is much below\nthe level of the river, and was a morass, or range of fens when our Doctor\nfirst took up his abode in Doncaster. This tract extends about four miles\nin length, and nearly three in breadth, and the security which it afforded\nagainst an attack on that side, while the river protected the peninsula by\nits semicircular bend on the other, was evidently one reason why the Romans\nfixed upon the site of Doncaster for a station. In Brockett's Glossary of\nNorth Country words, Carr is interpreted to mean 'flat marshy land,' 'a\npool or lake;' but the etymology of the word is yet to be discovered.\n\n\"These fens were drained and enclosed pursuant to an Act of Parliament,\nwhich was obtained for that purpose in the year 1766. Three principal\ndrains were then cut, fourteen feet wide, and about four miles long, into\nwhich the water was conducted from every part of the Carr southward, to the\nlittle river Torne, at Rossington Bridge, whence it flows into the Trent.\nBefore these drainings, the ground was liable to frequent inundations; and\nabout the centre there was a decoy for wild ducks; there is still a deep\nwater there of considerable extent, in which very large pike and eels are\nfound. The soil, which was so boggy at first that horses were lost in\nattempting to drink at the drains, has been brought {178} into good\ncultivation, (as all such ground may be) to the great improvement of the\ndistrict; for till this improvement was effected, _intermittent fevers and\nsore throats were prevalent there, and they have ceased from the time the\nland was drained_. The most unhealthy season now, is the spring, when cold\nwinds, from the north and north-east, usually prevail during some six\nweeks; at other times Doncaster is considered to be a healthy place. It has\nbeen observed that when endemic(?) diseases arrive there, they uniformly\ncome from the south; and that the state of the weather may be foretold from\na knowledge of what it has been at a given time in London, making an\nallowance of about three days, for the chance of winds. Here, as in all\nplaces which lie upon a great and frequented road, the transmission of\ndisease has been greatly facilitated by the increase of travelling.\"\n\nI feel certain of being excused for transcribing this long passage from\nSouthey. It would have been impossible to convey its whole meaning without\ngiving it entire. The continuation of the chapter is no less instructive\nand applicable to our subject, though more particularly so to an extension\nof the enquiry. The sore throats and intermittents, from which Doncaster\nhas been freed, by the drainage of Potteric Carr, informs us at once that\ndecomposing matter is the material by which the poison of fever is vivified\nand sustained, the wet and boggy state of the soil is just the condition,\nwhen no drainage exists, to bring into activity the germs of {179} disease,\nwhich otherwise would lie latent. So satisfied and acquainted are we with\nthe elements necessary for the production of fever, that we might as\ncertainly bring about an endemic intermittent by forming an artificial bog,\nas we could be sure of growing mushrooms by making a bed in the manner laid\ndown by gardeners for this purpose. Dr. Lindley also says, \"the _Polyporus\nfomentarius_ has been artificially produced in Germany, but merely by\nplacing wood in a favourable situation, and keeping it well moistened. Five\nor six crops were obtained in the year.\"\n\nLet warmth, moisture, darkness, and decaying matter be given, and inanimate\ndisintegrated particles will soon be converted into definite forms and\ncombinations instinct with life. It is by the unseen forms of living\nbeings, that the atmosphere is preserved from becoming charged with deadly\ngases; they take the first rank in the great scheme of animated beings, the\nplant first, and then the animal. \"Let the earth bring forth grass.\" \"Let\nthere be lights in the firmament.\" \"Let the waters bring forth the moving\ncreature, and fowl that may fly,\" and \"Let the earth bring forth the\ncattle, the creeping thing, and the beast.\" This is the order of creation,\nof living things, and the earth was prepared by vegetation for the animal\nworld. The work of conversion is accomplished by vegetation; and this is\nconsumed for the construction of higher organizations.\n\nThe laws which govern and control the universe, {180} are as definite and\nas wonderful among invisible atoms, as those which regulate the enormous\nmasses floating in space; and the time will come when the advancing\nintellect of man will measure and weigh the morbid poisons, as he measures\nand weighs the stars. Why should the laws of Epidemics be less understood,\nthan the laws which govern the course of comets? The aspirations of man\nhave led him to penetrate the heavens, which charm and inspire him; he\nstudies rather the more violent disturbing elements of nature, the\nthunder-cloud and the fire of heaven, than the silent pestilence which\nsteals over the earth. I cannot conceive it possible that the Intellects,\nwhich are occupied in procuring means for the Majesty of this empire to\nissue her mandates with the velocity of a spirit to the nethermost parts of\nthe earth, should be incapable of solving so deeply interesting a mystery\nas the causes and nature of pestilential diseases. It would seem that man\nprefers to issue a mandate of destruction many thousand miles distant, than\nto disarm the pestilence at his door. It is barely a century since Galvani\nobserved the twitchings in the muscles of a frog's leg, and the battery,\nstill named after him, has already become an agent of instantaneous\ncommunication between places many miles distant. But how many centuries\nhave passed away, each one succeeding the other, with its millions of\nvictims to epidemics? And where are the remedies for the evils? Drainage\nand cleanliness, with all their advantages, were better understood and more\nfully carried out by the ancient {181} Romans than by ourselves; there are\nmonuments, though crumbling to decay, to tell us of the vast enterprise of\nthese people and of the value they set upon a healthy and vigorous\nconstitution, and how well they understood the means of warding of disease.\n\nCultivation and drainage are now fully understood to be the basis by which\na healthy condition of air is to be obtained, next to that, cleanliness and\nventilation; if either be neglected a sickly, mouldy, and unwholesome\ncontamination of atmosphere ensues; the odour of a bog is proverbially\nmouldy, and so is that of an ill-ventilated house or cellar; dryness, or\nthe fresh pleasant scent of clean water, are the antagonists of these; the\naromatic odours of vegetation are opponents of putrefaction, and\nconsequently of the development of the lower forms of life. All\nempyreumatic matters prevent mouldiness and decomposition; and odours\narrest and prevent the growth of mouldiness. The oil of birch, with which\nthe Russia leather is impregnated, and which gives it so pleasant an odour,\neffectually prevents mouldiness, and consequently decay.\n\nLindley says, \"It is a most remarkable circumstance, and one which\n_deserves particular enquiry_, that the growth of the _minute fungi_, which\nconstitute what is called mouldiness, is _effectually prevented_ by any\nkind of perfume.\"[71] Cedar has {182} been used, from time immemorial, for\na like purpose; and I doubt not the recommendation of Virgil, before\nquoted, in reference to the burning of cedar, was founded on some practical\nutility of this kind, though its _modus operandi_ was unknown to him.\nAllied to these is a curious circumstance, and worthy attention. I copy the\nfollowing from an old work on Pestilences. \"It is remarkable that when the\nPlague raged in London, Bucklersbury, which stood in the very heart of the\ncity, was free from that distemper; the reason given for it is, that it was\nchiefly inhabited by druggists and apothecaries, the scent of whose drugs\nkept away the infection, which were so unnatural to the pestilential\ninsects, that they were killed or driven away by the strong smell of some\nsorts of them.\" \"The smell of _rue_, and the smoke of tobacco, were\nprescribed as remedies against the infection; but especially tar and pitch\nbarrels, which it was imagined preserved Limehouse, and some of the\ndock-yards from infection.\"[72]\n\nPitch and tar dealers are everywhere spoken of as being remarkably exempt\nfrom infectious diseases.\n\nCold infusion of tar was used in our colonies as a prophylactic against the\nSmall Pox. Bishop {183} Berkeley was induced to try it when this disease\nraged in his neighbourhood. The trial fully answered expectation--for all\nthose who took tar-water, either escaped the disease, or had it very\nslightly.\n\nTan yards and places in the immediate vicinity, are said to be free from\npestilences. The tanners of Bermondsey are said to have escaped the Plague\nof London, and one person only died in Gutter Lane, where was a tan yard.\nThe tanners of Rome are also stated to have been free from Plague. Dr.\nMcLean refers to the exemption of tanners at Cairo. _Tannin is prejudicial\nto most vegetables_,--but Dr. Lindley says it is not always so to fungi. \"A\nspecies of Rhizomorpha is often developed in tan pits.\" I should imagine\nthat neither plants nor insects would be found very abundantly, where\ntannin prevails; yet we find that the gall-nut is formed for the protection\nof an insect from injury by weather, and as a temporary means of\nsustenance.\n\nThe custom of fumigating with odoriferous substances, does not therefore\nappear upon this view of the matter to be destitute of importance; indeed,\nthe universal practice stamps it at once, as an efficacious remedy for the\npurposes of disinfection. The introduction of chlorine fumigation, seems to\nhave superseded, in a great measure, the use of fragrant herbs and woods;\nand it is questionable whether the substitution be altogether desirable or\n{184} advantageous. Many scents may be agreeably and usefully employed,\nwith much less chance of annoyance to the patient, and considerably less\ninjury to articles of furniture, &c.\n\nThe fumigations of sulphurous acid and chlorine are, perhaps, more adapted\nas disinfectants in uninhabited apartments;--their power to destroy\nvegetation, is well known. They have been used, chiefly, with the idea of\nneutralizing gaseous exhalations, particularly chlorine, as it tends to\ncombine with hydrogen, to form hydrochloric acid, and then to unite with\nammoniacal matters, forming hydrochlorate of ammonia. This, supposing\nnoxious or pestilential effluvia consisted of the ammoniacal exudations\nvariously combined, was an exceedingly efficacious method of rendering them\ninert; but as we feel convinced that no ammoniacal compound could possibly\nbe the cause of infection, we must look to the influence these gases\npossess over other forms of matter, and as they are so destructive, even in\nminute quantities, to vegetable existence, it is possible that their\nbeneficial effects may be due to this property. The immediate neighbourhood\nof gas works is prejudicial to vegetation, I imagine, from the amount of\nsulphurous vapours, and to this has been attributed the exemption of\npersons employed in these works. Many other instances might be cited of a\nsimilar nature.\n\nI have now to speak of medicinal agents, and here comes a considerable\ndifficulty. {185}\n\nIf we might believe all that has been written on the sure and certain\nremedies for the \"ills that man is heir to,\" we should be led to\nacknowledge that both nature and art were prodigal in antidotes and\nspecifics. The all-bountiful hand of nature, I do not doubt, has at the\nsame time scattered the seeds of good and of evil. The fertilizing showers\nfall to irrigate the soil, and produce food and nourishment to man; here\nand there is the reeking morass \"feeding unnatural vegetation,\" and if man\ntakes up his abode in its vicinity, the rains which made it unhealthy, have\nalso made it highly fertile; by labour and cultivation he may convert the\nmephitic bog into a waving corn-field, and the seeds of life and sustenance\nbe made to supplant the seeds of death and corruption.\n\nIt is generally believed, that where there are particular and specific\ndiseases, there also may be found appropriate and specific remedies; the\ndiscoveries of chemistry, it is not improbable, may in some respects have\nretarded the progress of natural medicine. In the early ages of the world,\nthe \"healing plant\" must have formed the staple of medical commerce, for\nthough Tubal Cain[73] has been considered as the first surgical instrument\nmaker, because he was the first artificer in brass and iron, we have not\ndiscovered that chemical compounds entered into the composition of physic,\ntill very {186} many years after his time. To the alchemists we owe the\nscience of chemistry, and much of the physic of the present day may be\ntraced to them. The multiplicity of ingredients which at one time entered\ninto the composition of one dose of physic could only be spoken of under\nthe title of \"legion.\" Who shall specify the active and curative ingredient\n(if there be one), when from five to a hundred may have been exhibited at\nthe same time? It has been the pride of our physicians, that the\npharmacopoeia has been simplified; it has not reached its most simple form\nyet. That many simple plants have specific and wonderful power over\ndisease, is an indubitable fact, but I firmly believe that the laudable,\nthough mistaken efforts of physicians to improve their effect by various\ncombinations, have been the means of throwing many valuable medicines into\noblivion; I must also add, that cheap physic and adulterations have had no\nsmall share too in the banishment of much valuable physic from ordinary\npractice. It has been believed, and I think with much reason, that a\nthorough search into the qualities of plants, would shew that \"they are\ncapable of affording not only great relief, but also effectual and specific\nremedies.\" \"That they are not already found, is rather an argument that we\nhave not been sufficiently inquisitive, than that there are no such plants\nendued with these virtues.\"\n\nOf the result obtained by medical treatment, in cases of epidemic or\ninfectious disease, it is most {187} difficult to speak, but as my province\nhere is only to shew that living germs are the morbific agents, I have but\nto refer to such remedies as have been most extolled in controlling these\naffections. The disinfectants have already been mentioned in a cursory\nmanner. An enumeration only of simple medicines used during the late\nEpidemic, shall conclude this work, as the treatment in former times could\nnot by any possibility furnish satisfactory information. Aromatics and\nfragrant stimulants have in all times taken the foremost rank with acids,\nsuch as vinegar, lime and lemon juice. Mr. Guthrie's adoption of lemon\njuice in preference to bark, which he said made him worse while suffering\nfrom an attack of fever, during the Peninsular campaign, and his speedy\nrecovery from the disease, though not from its effects, shews, when many\nothers can bear equal testimony to its value, that such a remedy though\nsimple is not to be despised.\n\nBut to the late Epidemic. Dr. Stevens' saline treatment, appears, on the\nwhole, to have been the most successful. Common salt was used both\nmedically and dietetically, and formed the greatest bulk of the medicine\nemployed. Chlorate of potash and carbonate of soda were added to the\nmedicine.\n\nThe nitro-hydrochloric acid was used with success at St. Thomas's Hospital.\n\nDr. Copland used chlorate of potash, bicarb. soda, hydrochloric, ether, and\ncamphor water.\n\nDr. Ayre's calomel treatment had as many, if {188} not more, opponents than\nadvocates. Phosphorus had several advocates.\n\nCreasote and camphor were lauded by some. The beneficial operation of all\nthese remedies might be explained on the theory here supposed, that living\ngerms are the cause of Epidemic disease, but the specific action of any one\nremedy has not yet had sufficient attention or trial to enable me to make\nany deductions of a satisfactory or conclusive nature.\n\nIn the uncertainty which generally prevailed as to the best method of\ntreating Cholera patients, I was induced (for reasons stated in a pamphlet\npublished last year) to try the efficacy of sulphur, which had been\nextolled as a specific. In its effects I was not disappointed; but as the\nresults are already before the public, I need not do more than refer to it\namong other remedies.\n\nI did not contemplate even alluding to this subject, as it would extend far\nbeyond my intended limits. This portion of the enquiry would be more\nproperly carried out by keeping records of cases, treated in accordance\nwith the view attempted to be established, and I have not the slightest\nhesitation in saying, that the most ample success would ultimately attend a\nwell directed practice, based upon the principles inculcated in these\npages.\n\n       *       *       *       *       *\n\n\n{189}\n\nCONCLUSION.\n\nIn making the foregoing sketch, I have attempted to put together some ideas\non a subject, which has for the last few years been a theme for meditation\nin leisure hours, viz. What are the causes of Epidemic, Endemic, and\nInfectious Diseases? The occurrence of Epidemic Cholera last year in this\ncountry, awakened a spirit of enquiry. Where there is unrest, whatever may\nbe the cause, there also is disquiet and discontent. When the oracles of\nthe age were consulted in the emergency, the discordant answers perplexed\nand confused the anxious searcher after truth. In the spring of last year,\nwhen the enemy was approaching, unseen and unheard, and the thousands of\nunconscious victims, who are now lying in their graves, were faithfully\ntrusting and fully relying on the heads of our profession, and the\nresources of our art, what was the state of our defences, and what the\nnature or character of our resistance? One considerable body of men would\ndischarge from a little tube of glass, a host of almost invisible globular\natoms of sugar, said to be as potent and inscrutably operative as the\nunseen enemy. These infinitesimal practitioners assured the people that\nthey \"_had powerful means of subduing the disease_,\" {190} but even they\ndiffered among themselves, though they carried out to the fullest extent\nthe doctrine of their leader, _similia similibus_, which we may suppose to\nrefer in this case to the minuteness of the opposing armamenta. Without,\nhowever, agreeing with this school, I may quote a passage from Dr. Curie,\nwhich is, alas! too true: \"We have shewn, as they must (allopathists), and\nmany of them do acknowledge, that they have no fixed basis, no natural law\nupon which their treatment rests.\"\n\nWho can deny the force of this observation? Sheltered by a principle, it\nmatters not how fallacious, a man is placed as behind a barrier. If with\nany reason it could be shewn that the infinitesimal doses, could by no\npossibility effect a cure in Cholera; if it could be demonstrated by any\nline of argument, that a poison, a living poison, circulates with the\nblood, or lodges in the tissues, the homaeopathist must fall; his\n\"electricity and mineral magnetism,\" and \"_powerful concentration of life\npower towards the digestive canal_,\" will stand for what they are worth.\nThat minute doses of medicine can exert an active influence over the body\nis not to be denied, but these must consist of powerful drugs, as arnica,\naconite, and nux vomica, with others, and it is more than probable, that of\nsuch medicines, an inconceivably small amount may produce a specific effect\nupon some portion of the organic nervous system.\n\nHow is it that a dose of nitre or digitalis, \"can {191} convert\ncheerfulness into low spirits,\" or a grain of red sulphuret of antimony,\n\"excite warmth and lively spirits?\"[74]\n\nWhy should indigo dyers become melancholy, and scarlet dyers choleric?[75]\nWe do not know. But there is one thing we most certainly do know, that a\npoison may be disarmed by an antidote, and the amount of the latter must be\nin proportion to that of the former, and as epidemic and contagious\ndiseases do most unquestionably depend upon poisons of a specific nature,\nand of great amount and activity, an infinitesimal remedy, however it may\nclaim to direct and control the organic forces, under slight and ordinary\ndisturbances, can be no more effectual in destroying the poison of fever,\nor small pox, than in neutralizing arsenic or prussic acid.\n\nThe uncertainty which generally prevails as to the treatment of Epidemic\ndiseases, Fevers, &c. induced me to put together the notions which are\ncontained in these pages, in the hope of leading to some definite ideas of\nthe causes of these affections, and consequently to a more uniform and\nscientific mode of treating them.\n\nI have endeavoured to shew that reproduction is a phenomenon inseparable\nfrom morbific matter, and that in all probability the vegetable kingdom is\nthe source of the germs.\n\n{192}\n\nThe train of argument adopted is such as appeared to me most natural for\nsuch an enquiry, and it rests now only with those who are capable of\ndeciding whether such a course, though (I am sensibly aware) not without\nmany faults in conception and execution, is calculated to advance the\nscience of medicine and the interests of mankind.\n\nThe real tree of knowledge, possesses in the spongioles of its roots, an\nelective property, by which truth alone can enter; nourished and sustained\nby this, it sends a fragrant incense and breathing odour on high, and\ndispels the mists of ignorance and superstition. In natural causes and\nreasonable deductions we must seek for instruction and solid information,\nfor in over-straining either nature or art, deformity and error must\ninevitably be the result.\n\nTHE END.\n\nNORMAN AND SKEEN, PRINTERS, MAIDEN LANE, COVENT GARDEN.\n\n       *       *       *       *       *\n\n\nNOTES\n\n[1] \"It matters little how vague and false hypotheses may appear at first:\nexperiment will gradually reduce and correct them, and all that is\nrequired, is industry to elaborate the proof, and impartiality to secure it\nfrom distortion.\"--_Sewell_ \"On the Cultivation of the Intellect.\"\n\n[2] It is stated by Mr. Crosse, of Norwich, that vaccination was adopted in\nDenmark, and made compulsory in 1800. After the year 1808 Small Pox no\nlonger existed there, and was a thing totally unknown; whereas during the\ntwelve years preceding the introduction of the preventive disease, 5,500\npersons died of the Small Pox in Copenhagen alone.--_Dr. Watson's\nLectures._\n\nDr. Blick, an intelligent Danish physician, corroborated the above\nstatement to Dr. Watson himself in the year 1838.\n\n[3] Philosophy of Life, Lecture 6, translated by the Rev. A. J. W.\nMorrison, M.A.\n\n[4] The following I quote from Dr. Fuller on Small Pox and Measles:--\n\n\"To this purpose some (and particularly Kircherus) are of opinion that\nanimalcules have been the causes of malignant and pestilential fevers in\nepidemic times, which differ in essence and symptoms, according to the\nnature and venoms of those creatures.\n\n\"Thus the atmosphere and air is filled both from above and beneath with\ninnumerable millions of millions of species or corpuscles, aporrhoeas,\nsteams, vapours, fumes, dust, little insects, &c. all which make it such a\nwonderful chaotic compost of things that contains the _seeds_ of good and\nevil to man as surpasseth the understanding (as I suppose) of even the\nhighest order of archangels.\"\n\n[5] I learn from an undoubted authority that the cow when \"slack of health\"\neats with avidity the \"field parsley;\" the sheep under similar\ncircumstances seeks the ivy, and the goat the plantain.\n\nFrom an equally good source I have the following: that rabbits and hares,\nwhen they are what is commonly called _pot-gutted_, seek the green broom,\nthough at a distance of _twenty miles_.\n\n[6] \"My settled opinion is, that in regard every effect is necessarily such\nas its cause; it must needs be that every sort of venomous fevers is\nproduced by its proper and peculiar species of virus.\n\n\"And that the manner and symptoms of every such fever is not so much from\nthe particular constitution of the sick; as from the different nature and\ngenius of their specific venom which caused them.\n\n\"And I conceive that venomous febrile matters differ not in degree of\nintenseness only, but in essence and _toto genere_ also; and that venomous\nfevers are for the most part contagious.\"--_Thomas Fuller, M. D. 1730._\n\"Another important class of organic poisons are those which when introduced\nin almost inappreciable quantities into the system, seem to increase in\nquantity; and which when communicated in the same inappreciable quantity\nfrom the individual poisoned to one who is healthy, excite the same series\nof febrile phenomena and local inflammation, and the same increase in the\nquantity of the poisonous agent.\"--_Med. Chir. Review._\n\n\"This unseen influence working in the body, presents very striking\nanalogies to the modes of operation of different poisons.\"--_Dr. Ormerod on\nContinued Fever._\n\n[7] I am aware that the vesicle does not here strictly bear the relation to\nthe original germ, supposing one active particle alone to be sufficient for\nits production, that the egg does to the bird, for in the former case\nmultitudes of active particles may have been generated from one. I have,\ntherefore, merely used this expression to signify an aggregation of vital\nforces, such as may be imagined to exist in the bird.\n\n[8] \"At an early period the form of the ovisacs is usually elliptical, and\ntheir size extremely minute,--their long diameter measuring in the ox no\nmore than 1/562 of an inch, so that a cubic inch would contain nearly two\nhundred millions of them. They are _at this time_ quite distinct from the\n_stroma_ of the ovarium; this forms a cavity in which they are loosely\nembedded.\"\n\n[9] Coleridge, p. 56.\n\n[10] \"All vegetables,\" says Sharon Turner, \"from that pettiness which\nescapes our natural sight, to that magnitude which we feel to be gigantic,\nhave these properties in common with all animals--organization; an interior\npower of progressive growth, a principle of life, with many phenomena that\nresemble irritability, excitability, and susceptibility, and a\nself-reproductive and multiplying faculty.\"--_Sharon Turner's Sacred\nHistory._\n\n[11] \"Plants highly sensitive to light are those of the leguminous, or Pea\nkind. They always close up in the evening and clasp their two upper\nsurfaces together, presenting only their backs to the air. Plants of\npinnated leaves, as the Tansy, are more sensible than these to the effects\nof light. They fold up when light is too strong, as in Robinia; it produces\nthe same effect as want of light. Its leaves close up, apparently, because\nthey are receiving too much. So they do if a hot iron be brought near them.\nThey contract as if to avoid the heat. Sensitive plants, and those of the\nOxalis Lent. are so sensitive that the least motion, even a breath of air,\nwill make them close.\"--_Sir J. Smith._\n\n\"The vitality of plants seems to depend upon the existence of an\nirritability, which although far inferior to that of animals, is\nnevertheless of an analogous character.\"--_Lindley's Introduction to\nBotany._\n\n[12] Provincial Medical and Surgical Journal. July 10th, 1850. No. xiv. p.\n367. \"Practical Observations on the Vaccination Question.\" By E. Oke\nSpooner, M. R. C. S., Blandford.\n\n\"If we examine the Cow Pox and the Small Pox microscopically, as I have\ndone very carefully in every stage, we find that the essential character\nconsists of a number of minute cells, not exceeding the 10,000th part of an\ninch in diameter, being about one-fourth smaller than the globules of the\nblood, containing _within their circumference many still more minute\nnuclei, and presenting_ beyond their circumference bud-like cells of the\nsame size and character as those contained within the circle. They exactly\nresemble in everything except the size, the globules of the yeast plant,\nthe Torula Cerevesiae. Now if we examine more circumstantially the\nanalogies of what I would call the Torula Variolae with the Torula\nCerevesiae, we observe the following corresponding facts.\n\n\"What do we accomplish by inoculation as it is called? Simply this. We take\non the top of a lancet, or an ivory point, a few of these minute cells or\ngerms, and we put them _in their appropriate nidus_, the subcuticular\ntissue, where, after a few days if they find their appropriate nutrient\nelements, they grow and multiply.\"\n\nSimon, Chemistry of Man, vol. i. p. 127. \"Macgregor ascertained that the\nair expired by persons ill of confluent Small Pox, contained as much as\n_eight_ per cent of carbonic acid, and in proportion as health was restored\nthe percentage was diminished to its natural standard.\" Carbonic acid is\nalso produced during the process of fermentation and germination.\n\n[13] See History of the Jews, p. 71.\n\n[14] It is said by Whewell, that the murrain is supposed to have fallen\nonly on the animals which were in the open pasture.--_History of the Jews._\n\n\"J. S. Michael Leger, published at Vienna, in 1775, a treatise concerning\nthe mildew as the principal cause of the epidemic disease among cattle. The\nmildew is that which _burns_ and _dries_ the grass and leaves. It is\nobserved early in the morning, particularly after _thunder-storms_. Its\npoisonous quality, which does not last above twenty-four hours, never\noperates but when it is swallowed immediately after its\nfalling.\"--_Mitchell on Fevers._\n\n[15] \"The prevalence of the south-east wind was observed to be particularly\nfavourable to the increase of both cholera and influenza: and I cannot but\nthink that this had some connexion with the general tendency exhibited by\nthe former to spread from east to west. Has the morbific property of this\nwind aught to do with the haziness of the air when it prevails--a haziness\nseen in the country remote from smoke, and quite distinct from fog? What is\nthis haze? In the west of England a hazy day in spring is called a\n_blight_.\"--_Dr. Williams' Principles of Medicine._\n\n[16] We are to understand also that some peculiar operation took place of a\nnature difficult to comprehend, which seems also to typify reproduction,\nfor the handfuls of ashes which Moses threw into the air _became a dust in\nall the land of Egypt_, thus signifying an enormous reproduction of atomic\nmatter.\n\n[17] The Chinese affect to trace the origin of Small Pox back to a period\nof at least 3000 years, or 20 years beyond the era of the Trojan war, 1212,\nA. C.\n\nThe Chinese pretend to discriminate no less than 40 different species of\nSmall Pox.\n\n\"They also pretend to discover whether a person has died by violence or\nfrom natural causes, not only after the body has been some time interred\nand decomposition of the softer parts has commenced, but even after the\ntotal disappearance of the soft parts, and when the dry skeleton alone is\nleft.\"--For the process, see _Hamilton's History of Medicine_, vol. i. p.\n31.\n\nTo give some notion of the state of Medical Science among the Chinese, I\nmay quote the following: \"The theory of the circulation of the blood, Du\nHalde affirms, was known by the Chinese about 400 years after the deluge;\nbe this assertion veracious or not, no correct knowledge up to the present\nday, do the nation possess of the circulating system of the human\nframe.\"--_China and the Chinese, Henry Charles Sirr, M. A._\n\nAccording to their anatomy, the trachea extends from the larynx through the\nlungs to the heart, whilst the oesophagus goes over them to the stomach.\n\n[18] \"And Aaron took as Moses commanded, and ran into the midst of the\ncongregation: and behold the plague was begun among the people; and he put\non incense and made an atonement for the people. And he stood between the\ndead and the living, and the plague was stayed.\"--_Numbers._\n\nThe practice of burning scented herbs has been observed in all times during\nan invasion of the plague, as a means of protection. Also wearing perfumes\nand aromatic preparations has been recommended. Whether they have any\ncounteracting influence, it is impossible to say.\n\nVirgil in the third Georgic speaks of a murrain among cattle. He says, if\nany wore a vestment made of wool from an infected sheep, fiery blains and\nfilthy sweat overspread his body, and ere long a pestilential fire preyed\nupon his infected limbs.\n\nIn his directions for preserving the health of flocks he says--\n\n \"Disce et odoratam stabulis accendere cedrum.\"\n\nThe motive for burning the fragrant cedar is not mentioned; we cannot doubt\nbut it was a good one, and having some great practical utility, from the\nfollowing line--\n\n \"Galbaneoque agitare graves nidore chelydros.\"\n\n[19] The earliest mention of this complaint upon which reliance can be\nplaced, is an ancient Arabic MS. preserved in the public library at Leyden.\n\"This year, in fine, the Small Pox and Measles made their first appearance\nin Arabia.\" The year alluded to being that of the birth of Mahomet, or the\nyear 572 of the Christian aera.--_Hamilton's History of Medicine_, vol. i.\np. 215.\n\n[20] Dr. W. A. Greenhill's translation.\n\n[21] The Black Assize at Oxford, 1572, is an instance in which a\npestilential vapour suddenly appeared in the court, \"whereby the judge,\nseveral noblemen, and more than 300 others, died within three days.\"\n\n\"Of an unaccountable vapour suddenly coming, I have this relation from\nRichard Humphrey, my neighbour, and a man of veracity, that on Wednesday,\nApril 27, 1727, as he and one Walter, were travelling a-foot from\nCanterbury; when they came to Rainham, they were assaulted with such a\nstrong loathsome stink, as he thought was like the stench from a corrupted\nhuman corpse. They were so offended at it, as thinking it was from carrion\nin that town, that they would not stay there to rest and refresh\nthemselves, but travelled on for about two hours, mostly in the stench, but\nsometimes out of it, till they came to the hill that leads down to Chatham:\nand there they went clear out of it and smelt it no more.\"--_Dr. Fuller_.\n\nIt appears that these persons did not fall sick of any disease, but the\nfact of itself is remarkable enough.\n\n[22] Hamilton's History of Medicine.\n\n[23] It has been said, that \"an induction once carefully drawn, is as\nperfect from a single instance as it is from ten thousand, and that it is\nonly an uncultivated mind which requires a load and accumulation of\nknowledge to assist his thoughts.\"--_Sewell_ \"on the Cultivation of the\nIntellect.\"\n\n[24] See Dr. Alison's Pamphlet on the Fever in Edinburgh.\n\n[25] Earthquakes have in all times been considered to have some connexion\nwith pestilences. \"A most grievous pestilence broke out in Seleucia, which\nfrom thence to Parthia, Greece, and Italy, spread itself through a great\npart of the world, from the opening of an ancient vault in the temple of\nApollo, and that it raged with so much fury as to sweep away a third part\nof the inhabitants of those countries it visited.\"--_Dr. Quincy, on the\nCauses of Pestilential Disease._\n\n\"Upon an earthquake the earth sends forth noisome vapours which infect the\nair; so it was observed to be at Hull in Yorkshire, by the Rev. Mr. Banks,\nof that place, after a small earthquake there in 1703, it was a most sickly\ntime for a considerable while afterwards, and the greatest mortality that\nhad been known for fifteen years.\"--_Anonymous_, 1769.\n\n[26] See Sharon Turner's Sacred History, text and notes, vol. i. p. 161 &\n162.\n\n[27]\n\n \"Each seed includes a plant; that plant, again,\n  Has other seeds, which other plants contain,\n  Those other plants have all their seeds; and those\n  More plants, again, successively enclose.\n  Thus ev'ry single berry that we find,\n  Has really in itself whole forests of its kind.\n  Empire and wealth one acorn may dispense,\n  By fleets to sail a thousand ages hence;\n  Each myrtle-seed includes a thousand groves,\n  Where future bards may warble forth their loves.\"\n\n[28] \"On June 5th, 1849, a man and his son, a lad aged 14 years, left Noss\nto fish, and when five miles out at sea, no vessel being in sight, they\nboth simultaneously became aware of a hot _offensive_ stream of air passing\nover them. It was so decided, that the crab pots were examined to discover\nif it were from them, but it did not, and five minutes after the father's\nattention was directed to the boy, who was vomiting and purging.\"--_Dr. Roe\non the Cholera at Plymouth, Med. Gaz. Aug. 24th, 1850._\n\n[29] Linnaeus remarked that Erigeron Canadense was introduced into gardens\nnear Paris from North America. The seeds had been carried by the wind, and\nthis plant was in the course of a century spread over all France, Italy,\nSicily and Belgium.\n\n[30] Hecker.\n\n[31] This is found most generally to be the case where rivers flow through\nuncultivated tracts of country. The Californian emigrants suffer much from\ndiarrhoea and dysentery, if they drink of the river and certain well waters\nof that gold district.\n\n[32] \"Purification from leprosy. As this fearful disease was contagious and\nhereditary to the third and fourth generation, the separation of lepers\nfrom the camp and congregation, and the destruction of infected houses and\nclothes, was of the utmost importance to the preservation of public health.\n\n\"Leprosy was of three kinds: 1st, Leprosy in man. 2nd, Leprosy in houses.\n3rd, Leprosy in clothes.\n\n\"Contagious or malignant leprosy was of two kinds, viz.\n\n\"1st. The white leprosy, or bright berat, which was the most serious and\nobstinate form which leprosy assumes. It exhibited itself as a bright white\nand spreading scale, on an elevated base; turning the hair white in\npatches, which were continually spreading.\n\n\"2nd. The black leprosy, or dusky berat, which was less serious than the\nforegoing. It did not change the colour of the hair, nor was there any\ndepression in the dusky spot; but the patches were perpetually spreading,\nas in the white leprosy.\"--_Analysis and Summary of Old Testament History._\n_Oxford._\n\n[33] The Mexican Aloe blows when nine years old, and then dies. At least\nthis is its usual course in the island of Cuba.\n\n[34] \"Ground that has not been disturbed for some hundred years, on being\nploughed, has frequently surprised the cultivator by the appearance of\nplants which he never sowed, and often which were then unknown to the\ncountry. The principle has been ascertained to be capable of existing in\nthis latent state for above 2000 years, unextinguished, and springing again\ninto active vegetation, as soon as planted in a congenial soil.\n\n\"In boring for water near Kingston on Thames, some earth was brought up\nfrom a depth of 360 feet, and though carefully covered with a hand-glass to\nprevent the possibility of other seeds being deposited on it, was yet in a\nshort time covered with vegetation.\n\n\"Turner says, from the depth, these seeds must have been of the diluvian\nage.\"--_Jesse's Gleanings._\n\n[35] Hamilton's History of Medicine, vol. ii. p. 276, note.\n\n[36] \"What I wish you to remark is this, that while almost all men are\nprone to take the disorder, large portions of the world have remained for\ncenturies entirely exempt from it, until at length it was imported, and\nthat then it infallibly diffused and established itself in those\nparts.\"--_Dr. Watson on the Principles and Practice of Physic._\n\nDr. R. Williams says, \"The seeds of intermittent fever lay dormant for\nmonths, it was not at all uncommon for cases of intermittent fever to be\nbrought into the hospital eight or ten months after the patients had\nsubjected themselves to the influence of paludal or marsh effluvia.\"\n\n[37] I have observed in the hot-houses, that many of the exotic plants,\nwhich are in company with the diseased vines, have been attacked, while\nothers again have been entirely free.\n\n[38] By causes of the greatest variety plants may become extinct for a\ntime. It is not very easy to trace them, but one fact may be mentioned in\nproof of the statement. Dr. Prichard states that vast forests are destroyed\neither for the purpose of tillage or accidentally by conflagrations. \"The\nsame trees do not reappear in the same spots, but they have successors,\nwhich seem regularly to take their place. Thus the pine forests of North\nAmerica when burnt, afford room to forests of oak trees.\"\n\n[39] Hecker says of Chalin de Vinario, that \"he asserted boldly and with\ntruth, that _all epidemic diseases might become contagious, and all fevers\nepidemic_,--which attentive observers of all subsequent ages have\nconfirmed.\" P. 60.\n\n[40] In 1539, the thirty-first year of Henry the Eighth, was great death of\nburning agues and flixes; and such a drought that welles and small rivers\nwere dryed up, and many cattle dyed for lacke of water; the salt water\nflowed above London Bridge.--_Stowe._\n\nIn 1556, the fourth of Mary, and the third of Philip, about this time began\nthe burning fevers, quarterne agues, and other strange diseases, whereof\ndied many.--_Stowe._\n\nThe next winter, 1557, the quarterne agues continued in like manner, or\nmore vehemently than they had done the last yere.--_Stowe._\n\n[41] Every writer on the climate of Egypt has remarked, that the Endemic\nFever which is so frequent, originating on the coast, particularly about\nAlexandria, becomes occasionally so virulent, that it cannot be\ndistinguished from the _true Plague._--_Robertson on the Atmosphere_, vol.\n2. p. 384.\n\n\"Endemial Fevers of every situation become occasionally so aggravated, that\nthey cannot be distinguished from such as originate from contagion; and in\nevery unusual virulence of this Endemic Fever, it is probable that it may\nbe propagated afterwards by contagion as every epidemic.\" _Ibid._ p. 388.\n\n[42] Dr. Ure.\n\n[43] \"The metamorphosis of starch into sugar depends simply, as is proved\nby analysis, on the addition of the elements of water. All the carbon of\nthe starch is found in the sugar; none of its elements have been separated,\nand except the elements of water, no foreign element has been added to it\nin this transformation.\"--_Liebig_, _Organic Chemistry_, p. 71.\n\n[44] As regards starch there appears to be some peculiar faculty regarding\nit. It is converted into sugar during the ripening of fruit, and it is just\npossible that being as it is of a cellular nature, the property of vitality\nmay attach to it until it has, by being converted into sugar, fulfilled its\ndestination.\n\n[45] Though I do not consider that the fermentation process is a fac-simile\nof diseased action, yet I think its phenomena generally afford an apt\nillustration of the changes which may be effected by living germs. Many\nable chemists still maintain the entire dependence of fermentation upon the\nTorula: \"M. Blondeau propounds the view that _every kind_ of fermentation\nis _caused_ by the development of fungi.\"\n\nThe varieties of opinions found in the literature of this subject, forms a\ncurious specimen of scientific enquiry, and is sufficient alone to convince\nus of its vast importance and extensive relations.\n\n[46] By Dr. Mantell.\n\n[47] Mitchell on Fevers.\n\n[48] We wonder, and ask ourselves: \"What does SMALL mean in\nNature?\"--_Schleiden's Lectures on Botany._\n\n[49] Speaking of the bunt in wheat: \"It appears certainly to be contagious,\nfrom numerous experiments, which shew that the contagious principle lasts a\nlong time. I have tried it myself; some, however, doubt it, but it cannot\nbe denied, that seed sown, infected with bunt, produces plants similarly\naffected; every one who has had the slightest experience must be convinced\nof it.\"--_Essay on the Diseases of Plants._ _Count R['e]._\n\n[50] We have already spoken of the effects of these poisons, and have\nstated that the amount of each poison capable of destroying the body is\npretty accurately known.\n\n[51] The italics are my own.\n\n[52] Gmelin says: \"But the mode of action in these transformations,\nsometimes admits of other explanations; and when this is not the case, our\nconception of it is by no means sufficiently clear to justify the positive\nassumption of this, so called contact-action or catalytic force, which,\nafter all, merely states the fact without explaining it\"--_Gmelin's\nHand-book of Chemistry_, vol. i. p. 115.\n\n[53] The history and symptoms of some epidemic diseases, such as cholera\nand influenza, are not inconsistent with the hypothesis that they are\ncaused by the sudden development of animalcules from ova in the blood. But\nthere is a total want of direct observation in support of this\nhypothesis.--_Dr. Williams' Principles of Medicine._\n\n[54] Since writing the above, I have referred for information on this\nsubject, and find, that the Anguillula aceti exhibits sexual distinctions;\nand that the ovaries of the females are situated on each side of the\nalimentary canal.--_Cyclo. Anat. and Phys. Art. Entozoa._\n\n[55] Speaking of the examination of the infusory animalcules--Mr. Kirby\nsays: \"But to us the wondrous spectacle is seen, and known only in part;\nfor those that still escape all our methods of assisting sight, and remain\nmembers of the invisible world, may probably _far exceed those that we\nknow_.\"--_Bridgewater Treatise_, vol. i. p. 158.\n\n[56] Mr. Owen has added another class, as the first, called Protelmintha,\nwhich comprises the cercariadae and vibrionidae.\n\n[57] \"It is probable that in the waters of our globe an infinity of animal\nand vegetable molecules are suspended, that are too minute to form the food\nof even the lowest and minute animals of the visible creation: and\ntherefore an infinite host of invisibles was necessary to remove them as\nnuisances.\"--_Bridgewater Treatise_, vol. i. p. 159.\n\n\"When Creative Wisdom covered the earth with plants, and peopled it with\nanimals, He laid the foundations of the vegetable and animal kingdoms with\nsuch as were most easily convertible into nutriment for the tribes\nimmediately above them. The first plants, and the first animals, are\nscarcely more than animated molecules,* and appear analogues of each other;\nand those above them in each kingdom represent jointed\nfibrils.\"+--_Bridgewater Treatise_, vol. i. p. 162.\n\n* Globulina and Monus. + Oscillatoria and Vibrio.\n\n[58] \"A treatise which should present a systematic arrangement of all the\ndiseases of plants, giving in detail the exact history of each, and adding\nthe means of preventing and curing them, would certainly be of the greatest\nutility to agriculture.\" --_Essay on the Diseases of Plants, Count Philippo\nR['e], translated into Gardener's Chron._\n\n[59] \"Plenck published a treatise on Vegetable Pathology, in which he\ndivided diseases into eight classes: 1. External injuries; 2. Flux of\njuices; 3. Debility; 4. Cachexies; 5. Putrefactions; 6. Excrescences; 7.\nMonstrosities; and 8. Sterility. And he concludes with an enumeration of\nthe animals which injure plants.\"--_Essay on the Diseases of Plants,\nGardener's Chronicle._\n\n[60] The Bunt. \"This disease appears at the moment of the germination of\nthe plant. The affected individuals are of a dark green, and the stem is\ndiscoloured. As the ears are issuing from the sheaths, their stalks are of\na dark green, but very slender. When the ear has fully grown out, its dull,\ndirty colour, causes it to be immediately distinguished from the healthy\nones, and it soon turns white.\"--_Essay on the Diseases of Plants._\n\n[61] _Vidi_ understood.\n\n[62] \"At the close of the year 1665,\" says Dr. Hodges, \"even women, before\ndeemed barren, were said to prove prolific.\"\n\n\"After the cessation of the Black Plague, a greater fecundity in women was\nevery where remarkable--a grand phenomenon, which from its occurrence after\nevery destructive pestilence proves to conviction, if any occurrence can do\nso, the prevalence of a higher power in the direction of general organic\nlife. Marriages were almost without exception prolific; and double and\ntreble births were more frequent than at other times.\"--_Hecker_, p. 31.\n\n[63] It is stated that on the decline of the Plague, 1665, those who\nreturned early to London, or new comers, were certain to be attacked. In\nproof of this the 1st week of November, the deaths increased 400, and\n\"physicians reported that above 3000 fell sick that week, mostly new\ncomers.\"\n\nSee also Dr. Copland's Dict. Pract. Med. Epidemic and Endemic Diseases.\n\n\"The hardy mountaineer is a surer victim of paludal fever, whether he\nvisits the low countries of the tropics, or the marshes of a more temperate\nclimate, than the feebler native of those countries.\"--_Dr. R. Williams on\nMorbid Poisons._\n\n[64] \"Substances presented to the gastro-intestinal surfaces, are mixed up\nwith various secretions, mucus, saliva, gastric juice, bile, pancreatic\nliquor, and special exudations from the peculiar glands of each successive\nsection, while aerial poisons, unmixed and unfettered, are applied at once\nto a surface on which, behind scarcely a shadow of a film, circulates the\nblood prepared, by the habitual action of the respiratory function, to\nabsorb almost every vapour, and every odour, which may not be too\nirritating to pass the gates of the _glottis_.\"--_Mitchell on Fevers._\n\n[65] Hecker on the \"Black Death.\"\n\n[66] The stomach in some cases is no doubt the medium by which some\ndiseases are contracted. It is well known, that in many places the water\ninduces diarrhoea, the permanent residents, however, may not suffer, but\nall new comers are more or less affected by drinking it.\n\n[67] \"Similar effects have been experienced from the use of mouldy\nprovisions.\"--_Dr. Lindley's Vegetable Kingdom._\n\n[68] \"Untold numbers die of the diseases produced by scanty and\n_unwholesome food_.\"--_Southey._\n\nA large, nay, a most extensive adulteration of flour with plaster of Paris\nwas detected not many years since. The flour was supplied by a contractor\nfor the manufacture of biscuits for the navy.\n\n[69] See Southey's Doctor, vol. ii. interchapter vi. p. 115, for an\nillustration of this subject.\n\n[70] Both these patients died.\n\n[71] \"A good part of the clove trees which grew so plentifully in the\nisland of Ternate, being felled at the solicitation of the Dutch, in order\nto heighten the price of that fruit, such a change ensued in the air, _as\nshewed the salutary effect of the effluvia of clove trees and their\nblossoms; the whole island, soon after they were cut down, becoming\nexceeding sickly_.\"\n\n[72] The observation is originally taken from the City Remembrancer, 133.\n\n[73] See Hamilton's History of Medicine, vol. i. p. 4.\n\n[74] Feuchtersleben's Medical Psychology, p. 176, 177.\n\n[75] Ibid. p. 321.\n\n       *       *       *       *       *\n\n\nCHANGES MADE AGAINST PRINTED ORIGINAL.\n\nPage 136. \"the idea of Protophyta, or first plants\": 'Prolophyta' in\noriginal.\n\nPage 140. \"an extensive bearing of each individual part\": 'indivdual' in\noriginal.","title":"Epidemics Examined and Explained: or, Living Germs Proved by Analogy to be a Source of Disease","tradition":"philosophy-ethics","translated_text":null,"word_count":46106}