« ПредыдущаяПродолжить »
THE problem of hereditary transmission, | pronounce the answers hitherto proposed physical and moral, although one of the deficient in the primary requisite of commost interesting of physiological problems, prehending all the phenomena. Neveris also one of the most baffling. In spite of theless, answers abound. Every cattleits obscurity, it fascinates the inquirer; per- breeder, who rises to the height of a haps with all the greater force because of theory, has his theory on this complex its obscurity, for, as Spinoza truly says, matter, and acts upon it in the breeding men cease to admire that which they fancy of cattle and poultry. Every village gosthey understand: tum enim vulgus rem ali- sip, every Mrs. Gamp, has her facts and quam se satis intelligere existimat quum her opinions, which, in expansive moments, ipsam non admiratur. The question of she delivers with great confidence. Every hereditary influence has descended from physician has his theory, especially with antiquity incumbered with prejudices and reference to the transmission of disease. deceptive facts, which seem coercive and Even the man of letters is not without his conclusive, but were in truth only one- generalization on the transmission of sided; and incumbered still more with genius: "all men of genius," he tells you, hypothesis formed in ignorance of Na-"have had remarkable mothers;" in supture's processes. It has reached us a problem still; every scientific mind not prepossessed by an hypothesis, nor content to disregard a mass of facts, must
Traité de l'Hérédité Naturelle dans les Etats de
Santé et de Maladie du Système Nerveux. Par le Dr.
On the Physiology of Breeding. Two Lectures de hivered to the Newcastle Farmers' Club. Bv Reginald resemble each other, are conveniently
port of which generalization he counts off upon his fingers the illustrations which occur to him, perfectly heedless of the mass of cases in which the mothers have not been remarkable.
The various theories imply variety of interest in the question, and a practical need for the solution. A subject at once so interesting and important may well neither be transmuted nor maintained in fixity. Only individuals exist; they re
in a form intelligible to the general reader, | the whole discussion of heritage must rest. and to clear up many misconceptions, The truth is this: Constancy in the transpopular and scientific, which at present ob- mission of structure and character from struct the question. The three works parent to offspring, is a law of Nature. placed at the head of this paper, with many others less directly bearing on the subject, will supply us with abundant facts, and may be recommended to readers desirous of pursuing the inquiry. Dr. Lucas has in two bulky octavos gathered from far and wide a mass of material, good, bad, and indifferent, with laudable diligence, but with a want of discrimination not so laudable. He is erudite, but he has les défauts de sa qualité. His erudition is utterly uncritical; and yet it is obvious that the sole value of the cases collected depends on their authenticity. It is the common error of erudite men to imagine that quantity supplies the place of quality. They fancy themselves rich when their purses are filled with forged notes; and so long as these notes are kept from presentation at the Bank, their delusion is untroubled. Dr. Lucas has far too many of these notes in his purse: the reader must take up his volumes with great caution. Mr. Orton makes no such erudite display; but he has collected some curious facts, both from his own experience and from the experience of other breeders. M. Girou is one of the authorities most frequently referred to by writers on this topic. To vast practical experience in cattle breeding he adds very considerable physiological knowledge and force of intellect.
That this truth is not a truism we shall show by at once contradicting, or at least qualifying it. The very same experience which guarantees the constancy, also teaches, and with almost equal emphasis, that this constancy is not absolute. Variations occur. Children sometimes do not resemble their parents; which accounts for the exclamation of surprise when they do resemble them. Nay, the children are sometimes not only unlike their pa rents, they are, in important characteristics, unlike their Species. We then call them Deformities or Monsters, because, while their Species is distinguished by having four legs, they themselves have six or none; while their Species possesses a complex brain, they are brainless, or have imperfect brains; while their Species is known by its cloven hoofs, they have solid hoofs, and so on." * Dissemblances as great are observable in moral characteristics. We see animals of ordinary aptitudes engender offspring sometimes remarkable for their fine qualities, and sometimes for their imbecility. The savage wolf brings forth occasionally a docile, amiable cub; the man of genius owns a blockhead for his son. In the same family we observe striking differences in stature, aspect, and disposition. Brothers brought up together in the same nursery, and under the same tutor, Heritage (l'hérédité), or the transmis- will differ as much from each other as sion of physical and mental qualities from they differ from the first person they meet. parents to offspring, is one of those gene- From Cain and Abel down to the brothers ral facts of Nature which lie patent to uni- Bonaparte, the striking opposition of chaversal observation. Children resemble racters in families has been a theme for their parents. Were this law not constant, rhetoric. Nor is this all. In cases where there could be no constancy of Species; the consanguinity may be said to be so the horse might engender an elephant, the much nearer than that of ordinary brothersquirrel might be the progeny of a lioness, hood, namely, in twins, we see the same the tadpole of a tapir. The law, however, diversity; and this diversity is exhibited is constant. During thousands of years in those rare cases where the twins have the offspring has continued to exhibit the only one body between them. The celestructure, the instincts, and all the charac-brated twins Rita and Christinaf were so teristics of the parents. Every day some one exclaims-as if the fact surprised him "That boy is the very image of his father!" yet no one exclaims, "How like that pug dog is to its parent!" Boys or pug dogs, all children resemble their parents. We do not allude to the fact Portugal, King of Tait's Magazine,
fused together, that they had only two
stitutés mirent au monde trois enfans sans avantbras ni jambes; d'autres dont parle Schmucker n'eurent que des enfans munis de douze orteils et douze doights."—Burdach, Traité de Physiologie, ii.
*"Flachsland rapporte que deux époux bien con
We Fly by Night-Chambers' Journal,.
legs between them: two legs and four classed under one general term, named arms and two heads; yet they were quite species; but this general term has no obdifferent in disposition. The same differ-jective existence; the abstract or typical ence was manifested in the celebrated Presburg twins, and in the African twins recently exhibited in London.
It is clear, then, that offspring do not always closely resemble parents; and it is further clear from the diversities in families, that they do not resemble them in equal degrees. Two brothers may be very unlike each other, and yet both like their parents; but the resemblance to the parents must, in this case, be variable. So that when we lay down the rule of constancy in transmission, we must put a rider on it, to the effect that this Constancy is not absolute, but is accompanied by a law of Variation. It is the intervention of this law which makes hereditary influence a problem; without it, heritage would be as absolute as the union of acids with bases.
Some philosophers have tried to explain the law of constancy in transmission, and its independence of the law of variations, by maintaining that it is the Species only, not the Individual, which is reproduced. Thus a sheep is always and everywhere a sheep, a man a man, reproducing the specific type but not necessarily reproducing any individual peculiarities. All sheep resemble each other, and all men resemble each other, because they all belong to specific types. What does the reader say to this hypothesis? Burdach, who adopts it,* adduces his facts: for example, a dog from whom the spleen was extirpated reproduced dogs with perfect spleens; an otter, deprived of its fore paws, produced six young with their legs quite perfect; in a word, "l'idée de l'espèce se reproduit dans le fruit et lui donne des organes qui manquaient au père ou à la mère." The hypothesis has seemed convincing to the majority of thinkers, but it labors under one fatal objection-namely, Species cannot reproduce itself, for Species does not exist. It is an entity, an abstract idea, not a concrete fact. It is a fiction of the understanding, not an object existing in Nature. The thing Species no more exists than the thing Goodness or the thing Whiteness. Nature only knows individuals. A collection of individuals so closely resembling each other as all sheep resemble each other, are conveniently
sheep, apart from all concrete individuals, has no existence out of our systems. Whenever an individual sheep is born, it is the offspring of two individual sheep, whose structures and dispositions it reproduces; it is not the offspring of an abstract idea; it does not come into being at the bidding of a Type, which as a Species sits apart, regulating ovine phenomena. The facts of dissemblance between offspring and parents we shall explain by-and by; they do not plead in favor of Species, because Species is a figment of philosophy, not a fact. The sooner we disengage our Zoology from all such lingering remains of old Metaphysics the better. Nothing but dreary confusion and word-splitting can come of our admitting them. Think of of the hot and unwise controversies respecting "transmutation of species," which would have been spared if a clear conception of the meaning of Species had been steadily held before the disputants, or if the laws which regulate heritage had been duly considered. In one sense, transmutation of Species is a contradiction in terms. To ask if one species can produce another; i. e., a cat produce a monkeyis to ask if the offspring do not inherit the organization of their parents. We know they do. We cannot conceive it otherwise. But the laws of heritage place the dispute in something of a clearer light, for they teach us that "Species" is constant, because individuals reproduce individuals closely resembling them, which is the meaning of "Species ;" and they also teach us, that individuals reproduce individuals varying in structure from themselves, which Varieties, becoming transmitted as part and parcel of the parental influence, will, in time, become so great as to constitute a difference in Species. It is in vain that the upholders of a "fixity of Species" assert that all the varieties observed are differences of degree only. Differences of degree become differences of kind, when the gap is widened: ice and steam are only differences of degree, but they are equivalent to differences of kind. If, therefore, "transmutation of Species" is absurd, "fixity of Species" is not a whit less so. That which does not exist, can neither be transmuted nor maintained in fixity. Only individuals exist; they re
their parents. Out of these resemblances we create Species, out of these differences we create Varieties; we do so as conveniences of classification, and then believe in the reality of our own figments.
"Les espèces," said Buffon, boldly, "sont les seuls êtres de la nature," and thousands have firmly believed this absurdity. The very latest work published on this subject,* reproduces the dictum, and elaborately endeavors to demonstrate it. "Les espèces sont les formes primitives de la nature. Les individus n'en sont que des reprèsentations, des copies." This was very well for Plato; but for a biologist of the nineteenth century to hold such language shows a want of philosophic culture. A cursory survey of the facts should have shown the error of the conception, if nothing else would. Facts plainly tell us that the individual and the individual's peculiarities, not those of the abstract Type, are transmitted. Plutarch speaks of a family in Thebes, every member of which was born with the mark of a spear-head on his body; and although Plutarch is not a good authority for such a fact, we may accept this because it belongs to a class of well authenticated cases. An Italian family had the same sort of mark, and hence bore the name of Lansada. Haller cites the case of the Bentivoglie family, in whom a slight external tumor was transmitted from father to son, which always swelled when the atmosphere was moist. Again, the Roman families Nasones, and Buccones, indicate analogous peculiarities; to which may be added the well-known "Austrian lip," and "Bourbon nose." All the Barons de Vessins were said to have a peculiar mark between their shoulders; and by means of such a mark, La Tour Landry discovered the posthumous legitimate son of the Baron de Vessins in a London shoemaker's apprentice. Such cases might be received with an incredulous smile if they did not belong to a series of indisputable facts noticed in the breeding of animals. Every breeder knows that the colors of the parents are inherited, that the spots are repeated, such as the patch over the bullterrier's eye, and the white legs of a horse or cow; and Chambont lays it down, as a principle derived from experience, that by choosing the parents you can produce
*"Cours de Physiologie Comparèe," par M. Flour
ens. 1856. A feeble and inaccurate book.
any spots you please. Girou noticed that his Swiss cow, white, spotted with red, gave five calves, four of which repeated exactly the spots of their mother, the fifth, a cow-calf, resembling the bull. And do we not all know how successful our cattle breeders have been in directing the fat to those parts of the organism where gourmandise desires it? Have not sheep become moving cylinders of fat and wool, merely because fat and wool were needed?
Still more striking are the facts of accidents becoming hereditary. A superb stallion, son of Le Glorieux, who came from the Pompadour stables, became blind from disease; all his children became blind before they were three years old. Burdach cites the case of a woman who nearly died from hemorrhage after blood-letting; her daughter was so sensitive that a violent hemorrhage would follow even a trifling scratch; she, in turn, transmitted this peculiarity to her son. Horses marked during successive generations with red-hot iron in the same place, transmit the visible traces of such marks to their colts. A dog had her hinder parts paralyzed for several days by a blow; six of her seven pups were deformed or excessively weak in their hinder parts, and were drowned as useless.* Treviranust cites Blumenbach's case of a man whose little finger was crushed and twisted, by an accident to his right hand: his sons inherited right hands with the little finger distorted. These cases are the more surprising, because our daily experience also tells us that accidental defects are not transmitted; for many years it has been the custom to cut the ears and tails of terriers, and yet terrier pups do not inherit the pointed ears and short tails of their parents; for centuries men have lost arms and legs, without affecting the limbs of our species. Although, therefore, the deformities and defects of the parent may be inherited, in general they are not. For our present argument it is enough that they are so sometimes.
Idiosyncrasies assuredly belong to the individual, not to the species; otherwise they would not be idiosyncrasies. Parents with an unconquerable aversion to animal food, have transmitted that aversion; and parents, with the horrible propensity for human flesh, have transmitted the propensity to children brought up away from them under all social restraints. Zimmer