Variation of Animals and Plants under Domestication^fn1

For critical examination in detail, Mr. Darwin's new book must be referred to the scientific journals and to cultivators and breeders. But, whatever audience he may address, a wide circle of general readers is sure to attend the founder of a new ism, and the word Darwinism has become as familiar as Galvanism or Mormonism. Readers from mere curiosity are likely to be somewhat disappointed in the present work. It is replete—some may say heavy—with facts; and facts in science, important as they are in this case both to practical men and philosophical investigators, are seldom half as enticing as speculations. To the "Origin of Species," moreover, there was the added zest of heterodoxy. Everybody hastened to read a book which was widely denounced, even by some scientific authorities, as dangerous or improper. No doubt the present volumes are flavored with the doctrine of their predecessor, which this is intended to support by evidence. But their main interest lies in the vast array of facts which are here collected and discussed, with the characteristic faithfulness and candor of a writer who was never known to tamper with the evidence, or to keep back anything which told against his theory. There is, moreover, plenty of hypothesis in the second volume, and that quite independent of the Darwinian theory.

These volumes are, in the main, a storehouse of facts relative to variation under domestication and kindred topics. The author announces that in a work to follow this he intends to treat of variation in a state of nature; and in yet another (may he live to complete such arduous undertakings!) he proposes to try the principle of natural selection by seeing how far it will serve to explain the geological succession of organic beings, their geographical distribution in past and present times, and their mutual affinities and homologies. He briefly informs us how the foundations of the views which he has lately made so famous were laid during his voyage in the Beagle, many years ago:

"When I visited the Galapagos Archipelago, situated in the Pacific Ocean, about five hundred miles from the shore of South America, I found myself surrounded by peculiar species of birds, reptiles, and plants, existing nowhere else in the world. Yet they all bore an American stamp. In the song of the mocking thrush, in the harsh cry of the carrion hawk, in the great candlestick-like opuntias, I clearly perceived the neighborhood of America, though the islands were separated by so many miles of ocean from the mainland, and differed much from it in their geological constitution and climate. Still more surprising was the fact that most of the inhabitants of each separate island in this small archipelago were specifically different, though most closely related to each other. The archipelago, with its innumerable craters and bare streams of lava, appeared to be of recent origin; and thus I fancied myself brought near to the very act of creation. I often asked myself how these many peculiar animals and plants had been produced: the simplest answer seemed to be that the inhabitants of the several islands had descended from each other, undergoing modification in the course of their descent; and that all the inhabitants of the archipelago had descended from those of the nearest land, namely, America, whence colonists would naturally have been derived. But it long remained to me an inexplicable problem how the necessary degree of modification could have been effected; and it would thus have remained for ever, had I not studied domestic productions, and thus acquired a just idea of the power of selection. As soon as I had fully realized this idea, I saw, on reading Malthus on Population, that natural selection was the inevitable result of the rapid increase of all organic beiugs; for I was prepared to appreciate the struggle for existence by having long studied the habits of animals."

In South America he had already been impressed with the fact of the prevalence of the same types, under different species or genera, throughout the length and breadth of the continent, and under the most diverse possible conditions ; while other parts of the world, such as South Africa and Australia, although incomparably more like to parts of South America than the different parts of that continent were to each other, were entirely different in their productions. Exhuming with his own hands the bones and armor of extinct gigantic quadrupeds of the same peculiar type with those which now exist there, and reflecting that the equally peculiar animals of Australia were preceded by forms of the same sort, the idea was forced upon him that, in time as in space, the similarity was to be explained by community of descent, the differences by modification and divergence under natural selection.

We have no intention to discuss the subject of natural selection, nor the theory with which Mr. Darwin has connected it; but we would note, both as an historical incident and a simple although restricted illustration, that anticipation of it which was made, half a century ago, by the distinguished author of the "Essay upon Dew," Doctor Wells, an American by birth, which Mr. Brace recently pointed out to Mr. Darwin, and which the latter, in the preface to the last edition of "The Origin of Species," pronounces to be the first recognition of the principle of natural selection which has been indicated. Dr. Wells, in a paper read before the Royal Society in 1813, after remarking that negroes and mulattoes enjoy immunity from certain tropical diseases, observes, 1st, That all animals tend to vary in some degree; 2d, That agriculturists improve their domesticated animals by selection; and adds that what is thus done "by art seems to be done with equal efficacy, though more slowly, by nature in the formation of the varieties of mankind fitted for the countries which they inhabit. Of the accidental varieties of man, which would occur among the first few and scattered inhabitants of the middle regions of Africa, some one would be better fitted than the others to bear the diseases of the country. This race would consequently multiply, while the others would decrease not only from their inability to sustain the attacks of disease, but from their incapacity of contending with their more vigorous neighbors. The color of this vigorous race, I take for granted, from what has already been said, would be dark; but the same disposition to form varieties still existing, a darker and darker race would in the course of time occur; and, as the darkest would be the best fitted for the climate, this would at length become the most prevalent, if not the only, race in the particular country in which it had originated." And so, conversely, of the white races in colder climates.

This "survival of the fittest" seems to us so inevitable that we are disposed to agree with Mr. Wallace when he declares that there is better evidence of such selecting power in nature than even direct observation would be, viz, the evidence of necessity. It inevitably must be operative, if animals and plants increase by reproduction in a geometrical ratio while their actual numbers remain, on the average, stationary, which is past all denying; if they tend to vary; and if variations are heritable, in other words, if offspring tends to resemble parents and grand parents, which no breeder doubts and few attentive readers of the present work will be likely to question; and, finally, if the world and the conditions of nature be subject to change, however slow; and the slower the better for natural selection.

How much of what was inexplicable or sterile in natural history and biology is to be explained or fecundated by this principle, or in this way of viewing things, is still under question. But, quite apart from the popular notoriety of Darwinism, it seems certain that these ideas have powerfully, and we suppose healthfully, stimulated scientific enquiry; and that their introduction within the last ten years marks an era in natural science. Most naturalists—perhaps we should rather say most natural philosophers—who have given attention to the subject appear to acknowledge natural selection as a vera causa, although few are convinced of its sufficiency, unaided, for the whole work which Mr. Darwin assigns to it. A greater number believe—indeed, the prevalent philosophical natural history of the day is largely based upon the notion, expressed or oftener implied—that species of the same genus, inhabiting the same or even more widely separated regions, are likely to have had a common origin; and, equally, that the plants and animals by which we are now surrounded are the modified representatives and descendants of those most like them in the last preceding geological age. That these advanced views, however, are attributable only in part to Mr. Darwin, is clear from the fact of their earlier promulgation, more or less distinctly, by such leading paleontologists as Pictet and Heer, and their later maintenance by Owen and De Candolle, quite irrespective of natural selection, which these writers make little of. So that, in fact, ideas of the derivation of present species from preceding ones are equally held by two parties—by those who offer a natural explanation of the process, and by those who have no explanation to offer for what they nevertheless suppose to have been a natural occurrence.

But we are not likely to forget that all such views, under whatever form or qualification maintained, do not pass unchallenged. If the new doctrines really prove to be false and mischievous, there is one naturalist, of highest prominence, whose conscience should never accuse him of having neglected to give due warning; who, upon all occasions, has iterated his ceterum censeo with a persistence worthy of old Cato himself—worthy, coming from such authority, of much consideration. Confident, therefore, that whatever is wrong will be duly set right, we may pass on from these debatable to more practical matters.

Eight chapters of the first volume and 40 of the 43 wood-cuts are given to the illustration of the varieties of dogs and cats; horses and asses; pigs, cattle, sheep, and goats; domestic rabbits; domestic pigeons, fowls, ducks, geese, peacock, turkey, Guinea fowl, etc., and a few pages to gold fish, hive bees, and silk moths. Pigeons receive the fullest consideration, two whole chapters being devoted to them. The 9th and 10th chapters are occupied with the cereal and some of the commonest culinary plants, fruits, and trees; and the 11th, with bud-variation and some connected matters; also with the action of foreign pollen on the fruit, seed-coats, or other organs of the mother plant, and the analogous effects in animals of a first impregnation upon subsequent offspring. In the second volume the interest, both practical and scientific, centers in the three chapters on inheritance, and in the five following upon crossing and its results, the good effects of crossing, the evil effects of close interbreeding, the advantages and disadvantages of changed conditions of life, etc. Two chapters follow upon selection by man and its consequences; then five in which the causes of variability and the laws of variation are laboriously discussed, and one in which the "provisional hypothesis of pangenesis" is propounded and explained.

The object of the hypothesis designated by this new word is, to connect intelligibly in some causal conception a variety of phenomena which, as an attentive consideration shows, must stand in some sort of relation to each other; to correlate the different modes of reproduction with each other and with growth, and also, in the lower animals, with the reproduction of lost parts; to form some notion as to how not only the characters but the peculiarities of parents are transmitted to offspring, and even are transmitted from a male parent through a daughter, in which they do not and cannot appear, to a grandson, in which they do; how certain diseases are heritable and may similarly pass over one generation to be developed in the next; how even remote ancestral characters may sometimes reappear in a descendant; how it is possible that a first impregnation may visibly affect a series of subsequent births; how hybrid plants, when self-fertile, in the succeeding generations are apt to mix, as it were in patchwork, rather than to combine the characters of the two constituent species, or to divide them among the individuals of a generation, some of them thus reverting to one of the parent types and some to the other. To explain these and the like, Mr. Darwin brings forward his "hypothesis of pangenesis, which implies that the whole organization, in the sense of every separate atom or unit, reproduces itself;" that "ovules and pollen-grains, and the fertilized seed or egg, as well as buds, include and consist of a multitude of germs thrown off from each separate atom of the organism," reproducing and multiplying themselves, like visible germs and cells, and aggregating by elective affinity to produce cells or organs like those from which they were derived ; so that if each cell of a plant has the actual or potential capacity of reproducing tho whole plant, it has it only in virtue of containing autonomous atoms derived from every part. So that "the child, strictly speaking, does not grow into the man, but includes germs which slowly and successively become developed and form the man." "Reversion depends on the transmission from the forefather to his descendants of dormant gemmules, which occasionally become developed." "When we hear it said that a man carries in his constitution the seeds of an inherited disease, there is much literal truth in the expression." "We cannot fathom the marvellous complexity of an organic being; but on the hypothesis here advanced this complexity is much increased. Each living creature must be looked at as a microcosm—a little universe, formed of a host of self propagating organisms, inconceivably minute, and as numerous as the stars in heaven." Physiologists, who chiefly will be interested in it, will comprehend the hypothesis from these brief statements, and will see that its germs are the considerably modified descendants of various earlier speculations. We have no space left for extracts and illustrations even of the less recondite and more practical portions of these teeming volumes.

Very interesting is the discussion of the ill effects of continued close breeding, which is so necessary to perpetuate and exalt the desirable characteristics of a race, yet at length so deteriorating that a cross must needs be resorted to; and we think that Mr. Darwin has fairly shown that the evil is not exclusively attributable to the cumulative inheritance of morbid tendencies common to both parents, but has some deeper foundation in nature: for, as he remarks, "It is unfortunately too notorious that men and various domestic animals, endowed with a wretched constitution, and with a strong hereditary disposition to disease, if not actually ill, are fully capable of procreating their kind." Domestication and civilization here serve as experiments to determine the point. Under natural selection these feeble individuals would be speedily made way with. We find in another chapter (xi., p. 214) an illustration of this, and of "sound sense" from the natural-selective point of view:

"Unconscious selection in the strictest sense of the word—that is, the saving of the more useful animals, and the neglect or slaughter of the less useful, without any thought of the future—must have gone on occasionally from the remotest period and among the most barbarous nations. Savages often suffer from famines, and are sometimes expelled by war from their own homes. In such cases it can hardly be doubted that they would save their most useful animals. When the Fuegians are hard pressed by want they kill their old women for food rather than their dogs, for, as we were assured, 'old women no use—dogs catch otters.' The same sound sense would surely lead them to preserve their more useful dogs when still harder pressed by famine."

While contending that no distinct line can be drawn between natural and artificial races, Mr. Darwin attributes the usually different aspect of the two to the fact that man selects and propagates modifications solely for his own use or fancy, and not for the creature's own good, while the wild animal, struggling with its incessant competitors and enemies, has every slight variation rigorously tested and preserved or rejected, and is thus kept in full healthful harmony with its surroundings. And he claims that the wide differences of opinion as to whether certain domestic races have descended from one or from several aboriginal stocks, is good evidence that there is no palpable difference between races and species. He effectively compares the firm belief of breeders, that the races which they are rearing and slightly modifying cannot have come from common progenitors, with that of the naturalist, who is sure of the contrary, though he knows not how nor when they arose, and who in his turn rejects the notion that the closely allied natural species which he discriminates ever descended from a common progenitor. Mr. Darwin is convinced that "the long-continued accumulation of beneficial variations will infallibly lead to structures as diversified, as beautifully adapted for various purposes, and as excellently co-ordinated as we see in the animals all around us." The relative potency of the variation and the selection he illustrates in this wise:

"If an architect were to rear a noble and commodious edifice without the use of cut stone, by selecting from the fragments at the base of a precipice wedge-formed stones for his arches, elongated stones for his lintels, and flat stones for his roof, we should admire his skill and regard him as the paramount power. Now, the fragments of stone, though indispensable to the architect, bear to the edifice built by him the same relation which the fluctuating variations of each organic being bear to the varied and admirable structures ultimately acquired by its modified descendants."

And then, on the question which must needs come up;

"In regard to the use to which these fragments may be put, their shape may be strictly said to be accidental. And here we are led to face a great difficulty, in alluding to which I am aware that I am travelling beyond my proper province. An omniscient Creator must have foreseen every consequence which results from the laws imposed by Him. But can it be reasonably maintained that the Creator intentionally ordered, if we use the words in any ordinary sense, that certain fragments of rock should assume certain shapes so that the builder might erect his edifice? If the various laws which have determined the shape of each fragment were not pre-determined for the builder's sake, can it with any greater probability be maintained that He specially ordained, for the sake of the breeder, each of the innumerable variations in our domestic animals and plants—many of these variations being of no service to man, and not beneficial, far more often injurious, to the creatures themselves? . . . If we assume that each particular variation was from the beginning of all time pre-ordained, the plasticity of organization which leads to many injurious deviations of structure, as well as that redundant power of reproduction which inevitably leads to a struggle for existence, and, as a consequence, to the natural selection or survival of the fittest, I must appear to us superfluous laws of nature. [Not superfluous, surely, if 'survival of the fittest,' 'excellent co-ordination,' and all the harmonious adaptation and diversity we behold are to result from the operation of these very laws.] On the other hand, an omnipotent and omniscient Creator ordains everything and foresees everything. Thus we are brought face to face with a difficulty as insoluble as is that of free-will and predestination."

The very same difficulty, indeed, and the same impossibility as that of drawing the limits between the fixed and the contingent, either in the material or the moral world, in which both volition and established order play their mingled parts. But in Mr. Darwin's parallel, to meet the case in nature according to his own view of it, not only the fragments of rock (answering to variation) should fall, but the edifice (answering to natural selection) should rise, irrespective of will and choice!

We are informed that the enterprising publishers of the American Agriculturist propose to reprint Mr. Darwin's new work, under an arrangement with the author. In England the first edition was exhausted within a week.