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ART. V.—The Variation of Animals and Plants under Domestication. By CHARLES DARWIN, M.A., F.R.S. Two Vols. 8vo. London: 1868.

NINE years have now elapsed since the publication of 'The 'Origin of Species,' a mere sketch, or preface, containing the conclusions to be proved in a large work then in course of preparation, with very few of the data on which they were founded. As it was arraigned at the bar of public opinion while most of the witnesses in its favour were absent, we cannot wonder at the verdict of non-proven having been recorded. Mr. Darwin could hardly expect judgment to be withheld for an indefinite time on so important a subject, which he himself brought into court. However, sub judice lis est. Mr. Darwin now brings a fresh batch of evidence, but still continues to deprecate any 'hostile conclusion' because of the evidence as yet unpublished, which at the present rate of publication will be finally brought before the world eighteen years hence. By adopting this deductive method, by publishing the conclusions first, and the facts in a piecemeal fashion afterwards, he has made it almost impossible to give a fair decision on the whole of the theory. Nevertheless the 'Origin of Species' has exercised a very marked influence on the study of natural history, not altogether from the views therein advanced being accepted, but because it is in the main an expression of the disbelief in special creations that has been gradually increasing among scientific men, and because it explains, better than any other theory, large and diverse classes of facts. Isidore Geoffroy Saint-Hilaire in France, and Mr. Wallace in England, had already arrived very much at the same conclusions, and even had Mr. Darwin's book never been written, there can be little doubt but that some similar hypothesis would have sprung up. It must therefore be looked upon not so much as the product of the investigations of one man, as the necessary result of the progress of natural history during the last fifty years.

In attempting to grapple with a most complex and difficult problem Mr. Darwin is worthy of all praise, for he has brought to bear upon it the very highest powers of observation, and has devoted to it the labour of nearly forty years. Nor has he rushed into conclusions without due care and deliberation; step by step he was led on:—

'When I visited,' he writes, vol. i. p. 9, 'during the voyage of H.M.S. "Beagle," the Galipagos Archipelago, [Galapagos] situated in the Pacific Ocean about 500 miles from the shore of South America, I found

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myself surrounded by peculiar species of birds, reptiles, and plants, existing nowhere else in the world. Yet they nearly 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 neighbourhood 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.'

From his return to England in 1837 up to the present day, he devoted himself to the investigation of the means by which species could be modified, by studying the variation of plants and animals under domestication, and thus he was led to recognise the wonderful results of selection by man:—

'As man can produce and certainly has produced a great result by his methodical and unconscious means of selection, what may not nature effect? Man can act only on external and visible characters: nature cares nothing for appearances, except in so far as they may be useful to any being. She can act on every internal organ, on every shade of constitutional difference, on the whole machinery of life. Man selects only for his own good; Nature only for that of the being which she tends. Every selected character is fully exercised by her; and the being is placed under well-suited conditions of life. Man keeps the natives of many climates in the same country; he seldom exercises each selected character in some peculiar and fitting manner; he feeds a long and a short-beaked pigeon on the same food; he does not exercise a long-backed or a long-legged quadruped in any peculiar manner; he exposes sheep with long and short wool to the same climate. He does not allow the most vigorous males to struggle for the females. He does not rigidly destroy all inferior animals, but protects during each varying season, as far as lies in his power, all his productions. He often begins his selection by some half-monstrous form; or, at least, by some modification prominent enough to catch his eye, or to be plainly useful to him. Under nature the slightest difference of structure or constitution may well turn the nicely-balanced scale in the struggle for life, and so be preserved.' (Origin of Species, p. 83.)

He observed that in a state of nature more animals were

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born than could possibly remain alive, and that in the struggle for life thus rendered inevitable, only the hardier or most favoured individuals could survive to propagate their kind, and thence he inferred that natural selection operating on the principles of heredity and variation in each wild plant and animal was similar in kind to selection by the hand of man; and that species, genera, and orders sprang from the one, just in the same way as varieties, breeds, and races are formed by the other.

In these two volumes on the variation in plants and animals under domestication, delayed, as we regret to learn, by the ill-health of the author, we have the first instalment of the evidence in favour of the mutability of species. They are to be followed by a second work on the mutability of animals in a state of nature, in which the individual differences presented by plants and animals, and the difficulty of defining species from geographical races and varieties, will be discussed, as well as the results of the struggle for existence, and the bearing of natural selection. In a third and last the principle of natural selection is to be tested by its application to widely diverse phenomena, the different modes of life manifested within geological time, its distribution both in past and present time, and the affinities and homologies that it presents. We heartily wish Mr. Darwin God-speed in carrying to its completion this gigantic task.

Before we discuss the relation between varieties caused by the hand of man and species formed under natural conditions of life, it is very necessary to define what is meant by the term species. Has it an objective existence in nature, or is it merely subjective, formed in the human mind for the purpose of grouping like forms together? In answering this question we are reminded of the controversy that raged between the nominalists and realists throughout Europe in the Middle Ages. It appears almost as if the realistic doctrine, driven out of the schools of philosophy, had taken refuge in those of natural history. Linnæus held that not only were species objective but that genus also had a real existence. 'Species tot numeramus quot diversas formas ab initio produxit Infinitum Ens. … Genus omne est naturale in primordio tale creatum.'* Were this view correct there would be comparatively little difficulty in classification, for each species would be perfectly defined from every other, without any of those intermediate forms which are stumbling blocks in the path of rigid systematists.

* Phil. Bot. p. 99. 8vo. Stockholmiæ, 1751.

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Linnæus himself perceived that his realistic definition would not apply in all cases, and therefore to get out of the difficulty framed variable genera, such as cacti, primulæ, aloes. Moreover in another work, he gives up the very principle for which he contended by saying 'novas species immo et genera ex copulâ diversarum specierum in regno vegetabilium oriri primo intuitu paradoxum videtur; interim observationes sic fieri non ita dissuadent.'* The state of uncertainty as to what really constitutes a species is proved by the difference in the views of botanists as to the number of known species of plants, the minimum number being given as eighty thousand, the maximum as a hundred and fifty thousand.†

Buffon, on the other hand, reproduces the old Platonic doctrine of an ίδέα:—

'Un individu, de quelque espèce qu'il soit, n'est rien dans I'Univers; cent individus, mille, ne sont encore rien; les espèces sont les seuls êtres de la Nature; êtres perpétuels aussi anciens, aussi permanens qu'elle, que pour mieux juger, nous ne considérons plus comme une collection ou une suite d'individus semblables, mais comme un tout indépendant du temps; un tout toujours vivant, toujours le même; un tout qui a été compté pour un dans les ouvrages de la création et qui par conséquent ne fait qu'une unité dans la Nature.'‡

By 'individuals being nothing' he means simply that they are ephemeral as compared with species, and merely the manifestation in time and space of the ίδέα that is independent of both. We may justly ask of Buffon the same question which the great father of natural history put to Plato, 'How do you know of the existence of this ίδέα, this µέγα τι ύπ ρ ήµ ν?' We can apply our five external senses to the individual, but we cannot bring the test of our experience to bear upon the ideal species; we have therefore no right to assume that the latter has an objective existence in nature. Professor Agassiz follows Buffon in part, in considéring individuals to be 'the transient representatives of all those organic principles which certainly have an independent immaterial existence, since they outlive the individuals that embody them, and are no less real after the generation that has represented them has passed away.'§ He seems, however, to have failed in grasping the idea of

* Amœn. Acad. vol. i. p. 70. 1744.

† J. D. Hooker, 'Botany of Antarctic Voyage of "Erebus" and "Terror."' 1839–43. Flora of Tasmania. Introduction. 4to. London.

‡ Histoire Naturelle, tom. ix. p. xxi. 8vo. Paris, 1769.

§ Agassiz, 'Methods of Study in Natural History.' Boston, 1864.

 

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species, for at one time he inclines to the realistic view that it is created by God; at another to the nominalistic, that it is a mere 'category of thought.' The Platonic and realistic views are therefore clearly as untenable in natural history as they are in philosophy. How, then, do we get our species? We classify the varying forms of life around us by placing all those individuals that resemble one another in certain points in the same division; the mental abstraction derived inductively from the comparison of the individuals in that division we call a species. In like manner we group species into genera, genera into families; the individual occupying to the species the same classificatory relation that the species holds to the genus, and at the same time being the only entity that has an objective existence. When, therefore, Mr. Darwin contends that variety is an incipient species, and that species, genera, and orders are merely certain stages of descent from some one remote ancestor, he is merely attacking general terms that are the result of an induction formed for our own convenience, and not anything that can be considered sacred and above criticism. For the universally received definition of species as 'a collection of similar individuals produced from like parents, and giving birth to like offspring,' he merely adds, with Lamarck, 'so long as the environment does not alter to such a degree as to cause corresponding modifications in their habits, characters, and forms.' He does not attempt to overthrow the classification which is universally received, but to attach a different meaning to the general terms employed. Whatever theoretical considerations a naturalist may hold, species must be treated as fixed in relation to the short life of man as well as the higher generalisations, genera, families, orders.

All naturalists are agreed that plants and animals may vary within certain limits. Mr. Darwin in this work shows to what extent this power of variation may be manifested in the domesticated forms. His labours have resulted in a series of monographs on the origin of the breeds and varieties now under the dominion of man, in which he has condensed all the light thrown by history and archæology on a highly difficult and obscure subject.

We will begin with the dog. This animal has been so long the servant of man that its wild source cannot be determined with absolute certainty. According to M. de Blainville, it has descended from a form now extinct; according to M. Buffon, it is probably derived from the jackal (canis aureus); according to others, from a modified wolf. The first of these views is probably untrue, because of the wonderful tenacity with which

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the various species of the genus canis cling to their old haunts in highly cultivated districts. The fox and the wolf, for instance, still abound in Europe, and are among the most cosmopolitan of the wild animals, fitted to endure all the varieties of climate, from the pole to the equator. It is therefore extremely improbable that the early progenitor of our dogs, which exhibit a like elasticity of constitution, should have become extinct. Pallas, followed by Ehrenberg, Colonel Hamilton, and other naturalists, considered that it is descended from several species, because of the great difference between the breeds, and because, in the most ancient period known to history, several kinds existed closely resembling, or identical with, those still alive:—

'On an Assyrian monument, about 640 B.C, an enormous mastiff is figured; and, according to Sir H. Rawlinson (as I was informed at the British Museum), similar dogs are still imported into this same country. I have looked through the magnificent works of Lepsius and Rosellini, and on the monuments from the fourth to the twelfth dynasties (i.e. from about 3400 B.C. to 2100 B.C.) several varieties of the dog are represented; most of them are allied to greyhounds. At the latter of these periods a dog resembling a hound is figured, with drooping ears, but with a longer back and a more pointed head than in our hounds. There is also a turnspit, with short and crooked legs, closely resembling the existing variety; but this kind of monstrosity is so common with various animals, as with the Ancon sheep, and even, according to Rengger, with jaguars in Paraguay, that it would be rash to look at the monumental animal as the parent of all our turnspits. Colonel Sykes has described an Indian pariah dog as presenting the same monstrous character. The most ancient dog represented on the Egyptian monuments is one of the most singular; it resembles a greyhound, but has long pointed ears and a short curled tail. A closely allied variety still exists in Northern Africa; for Mr. E. Vernon Harcourt states that the Arab boar-hound is an eccentric hieroglyphic animal, such as Cheops once hunted with, somewhat resembling the rough Scotch deer-hound; their tails are curled tight round on their backs, and their ears stick out at right angles. With this most ancient variety a pariah-like dog co-existed.' (Vol. i. p. 17.)

Thus there is clear proof of the existence of different breeds closely resembling our own from four to five thousand years ago; and while man was universally considered to be only six thousand years old, this fact was sufficient to prove the multiple origin of the dog, for the one or two thousand years between the Assyrian dynasty and the creation would hardly have been sufficient to produce such marked variations from one original stock. But now modern discoveries in France, Germany, and Britain have shown that man existed on the earth at an epoch

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enormously removed from the very dawn of history. When he first made his appearance in Western Europe as a hunter of the reindeer, bison, musk-sheep, and great woolly mammoth, and lived in continual dread of the gigantic cave and grizzly bears, lions and hyænas, he was most probably unacquainted with the use of the dog. It is undoubtedly true that the remains of the larger breeds so closely resemble those of the wolf, abundant at the time throughout Europe, that extreme difficulty is felt in determining with absolute certainty the bones of the two animals. Were the Esquimaux dogs extinct it would be almost impossible to infer that they ever existed, because they approximate so closely to the wolf of those high latitudes. It is therefore possible that a race of dogs may have been subject to the post-glacial savage, but if so it must have been identical in form with the wolf. The evidence, on the other hand, brought forward by M. Lartet is opposed to this view. He acutely argues that the presence of the spongy bones, such as vertebræ and the like, that are invariably eaten by our dogs, in the refuse heaps left behind in the caves of the Dordogne and Vezère, is direct proof that the hunters of reindeer living at that time in the country were not acquainted with the dog.

The most ancient form is that found by Professor Steenstrup in the Danish shell mounds, that were accumulated during the Neolithic or later Stone Age. In Switzerland also, the same kind of dog, closely allied to the beagle (Torfhund) occurs in the pile-dwellings of the same relative age, as well as in the lacustrine marls of Italy. Its uniformity of character in these three countries leads Dr. Rutimeyer to infer that it was exposed to like conditions of life, and probably that it was half wild, like the Australian dingo. In the Bronze Age a larger breed makes its appearance both in Switzerland and Denmark, probably imported by the bronze-using invaders, who drove out the ancient stone-using dwellers in Europe. From that time down to the present day, as M. de Blainville has proved, the various breeds have continued to increase in number—'à mesure que la civilisation a demandé à cet animal des services plus variés et plus étendus.'

But although such vast antiquity must be ascribed to the dog, amply sufficient for the different varieties to have widened and deepened into the distinct breeds at the time we have first noticed in history, it is on the whole probable that the animal springs not from one domesticated wild species, but from several. The principal argument in favour of this view is based on the strong resemblance of the dog to the indigenous

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species of Canidæ which inhabit the same countries, and on the fact that it will breed freely with several wild species. The late Sir John Richardson remarked that the only difference between the dogs of the Indians and the North American wolves is merely that the latter are larger and stronger.* 'I have more than once,' he writes, 'mistaken a band of wolves for the dogs of a party of Indians; and the howl of the animal of both species is prolonged so exactly in the same key, that even the practised ear of an Indian fails at times to discriminate them.' The Esquimaux dogs are not only extremely like the grey wolves of the Arctic circle in shape and colour, but also rival them in size. 'The dog has generally a shorter tail than the wolf, and carries it more frequently curled over the hip; but the latter practice is not totally unknown to the wolf, although that animal when under the observation of man, being generally apprehensive of danger or on the watch, seldom displays this mark of satisfaction. I have, however, seen a family of wolves playing together occasionally carry their tails curled upwards.' This observation is very valuable, because it does away with a characteristic point of difference between the two animals insisted upon by some naturalists. But there is a deeper affinity between the two animals than mere outward resemblance or habit, which, tested by the ordinary definition of a species, would at once decide that they belong to one and the same. The Esquimaux frequently take the whelps of wolves† to improve their breed of dogs, and therefore the two freely intercross. The Hare Indian dog, also, is another case in point, bearing the same relation to the prairie wolf that the Esquimaux bears to the great grey wolf. In Guiana the natives have partially domesticated two aboriginal species, and still cross their offspring with wild stock. The shepherds' dogs of the Old World have a strong resemblance to the wolf. That of Hungary has been mistaken for the latter animal; and in the days of Columella the two animals must have been remarkably alike in Italy, for he advises shepherds to keep white dogs, that they might not be killed in mistake for wolves. Pennant also describes a breed of curs in Scotland of a most wolfish aspect, derived from a cross between a dog and a wolf.

'With respect to jackals,' Mr. Darwin writes, vol. i. p. 24, 'Isidore Geoffroy Saint-Hilaire says that not one constant difference can be pointed out between their structure and that of the smaller races of dogs. They agree closely in habits: jackals when tamed

* Fauna Borealis Americana, p. 64.

† Darwin p. 23.

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and called by their master wag their tails, crouch, and throw themselves on their backs; they smell at the tails of dogs, and void their urine sideways. A number of excellent naturalists from the time of Güldenstädt to that of Ehrenberg, Hemprich, and Cretzschmar, have expressed themselves in the strongest terms with respect to the resemblance of the half-domestic dogs of Asia and Egypt to jackals. M. Nordmann, for instance, says, "Les chiens d'Awhasie ressemblent étonnement à des chacals." Ehrenberg asserts that the domestic dogs of Lower Egypt, and certain mummied dogs have for their wild type a species of wolf (C. lupaster) of the country: whereas the domestic dogs of Nubia, and certain other mummied dogs, have the closest resemblance to a wild species of the same country, vix. C. sabbar, which is only the form of the common jackal. Pallas asserts that jackals and dogs sometimes naturally cross in the East; and a case is on record in Algeria. The greater number of naturalists divide the jackals of Asia and Africa into several species, but some few rank them all as one.'

All these cases are in favour of the truth of Mr. Darwin's conclusion that the dog is not derived from one wild progenitor, but from many belonging to distinct species. The strong resemblance between the domestic and wild Canidæ, both in the Old and New Worlds, can hardly be accounted for by modification caused by both being exposed to the same climatal conditions in the several countries; an hypothesis which must be assumed to be true on the theory of the domestic dogs having sprung from some one wild species.

Whichever of these views be entertained, the free intercrossing in America with the Arctic and prairie wolves and other Canidæ, and in the Old World with the wolf and the jackal, proves the very important fact that the dog, somehow or another, has the reproductive system so profoundly affected as to cause it to breed freely with diverse wild species which have never been known to breed together in a state of nature. There is not a single case on record of a hybrid between a wolf and jackal, although both inhabit the same area in Asia and Africa. The cases of sterility between some dogs and these two animals observed in the Jardin des Plantes have very little or no weight in the argument, because in both cases the animals were kept in close confinement, and because the wild origin of the dog was not ascertained in each experiment. Had a modified descendant of a wolf, such as the Esquimaux dog, been submitted to the jackal, or that of the jackal to the wolf, either less fertility or absolute sterility might be expected to occur, because in both there must exist, in a greater or less degree, the hidden cause of the wolf and the jackal remaining distinct in their wild state. This point has not been noticed by Mr.

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Darwin when he infers, from the experiments of M. Flourens and others, that between certain breeds of dogs and some of their supposed aboriginal parents a certain degree of sterility 'has been retained or even acquired.'

The differences between the various breeds of dogs are almost too obvious to need special remark. If, as is most probable, they are descended from different species, the specific form will account to a certain extent for their diversity.

'For instance, the form of the greyhound may be partly accounted for by descent from some such animal as the slim Abyssinian canis simensis with its elongated muzzle; that of the larger dogs from the larger wolves, and the smaller and slighter dogs from jackals, and thus perhaps we may account for certain constitutional and climatal differences.' (Vol. i. p. 33.)

In the case, however, of the dogs belonging to civilised communities, free intercrossing has so obscured the original stocks that they cannot be recognised with certainty. By far the greater number of the breeds in civilised countries have been formed by careful selection. We seek in vain for thorough-bred terriers, spaniels, pugs, &c. among savages, because they are the result of the art of the trainer directed to a special end, which in all these cases is that ministering not to the necessity but to the pleasure of man. While man subsisted by hunting, the dog never passed beyond the hunter state; and even long after he took to a pastoral life, as in the case of the Stone-folk living in the Swiss Pfahlbauten, the dog was not trained to any other purpose. The gradual increase, therefore, in the number of breeds, other than those used for hunting, is direct evidence of the progress of man from the hunter state towards the higher forms of civilisation.

The dog presents variations from the ordinary canine type, apart from mere size, form, or colour, which if observed in a state of nature would be considered of specific value. Thus the Turkish or Egyptian dog is naked and possessed of few teeth, which in some cases are reduced to one molar in each jaw; others, again, have more than their full complement of teeth, the supplementary one being developed either in the lower or the upper jaw. Sometimes also there is an additional fifth toe added to the hind foot. These characters have not been rendered constant because man does not care much about them. Had they contributed to his pleasure or profit, as much as the form and fleetness of his greyhounds, the size of his mastiffs, or the stubbornness or ferocity of his bulldogs, they would probably have characterised breeds as distinct from other dogs as the recent hyæna from the extinct hyænodon. The English

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pointer and the Newfoundland dog show how completely the form may be altered within a comparatively short time.

'Our pointers are certainly descended from a Spanish breed, as even their names, Don, Ponto, Carlos, would show; it is said that they were not known in England before the revolution of 1688; but the breed since its introduction has been much modified, for Mr. Borrow, who is a sportsman and knows Spain intimately well, informs me that he has not seen in that country any breed "corresponding in figure with the English pointer; but there are genuine pointers near Xeres which have been imported by English gentlemen." A nearly parallel case is offered by the Newfoundland dog, which was certainly brought into England from that country, but which has since been so much modified that, as several writers have observed, it does not now closely resemble any existing native dog in Newfoundland.'(Vol. i. p. 42.)

The most important inferences affecting the question of selection, that can be drawn from the study of the dog, are, that breeds as widely diverse as species in nature have been formed artificially, and that they cross freely with wild allied species, which will not naturally breed together.

The domestic cat, on the other hand, known more than two thousand years ago by our Aryan ancestors in India, and in Egypt for a considerably longer period, presents but very few variations. This probably is brought about by the continual intercrossing that flows from the habit of nocturnal prowling, which renders it almost impossible to preserve the purity of a breed. It breeds freely with the wild cat (F. sylvestris) in North Britain, in Algiers with F. Libica, in South Africa with F. cafra, in India with F. chaus. The mummied cats of Egypt belong, according to M. de Blainville, to three distinct species, F. bubastes, F. caligulata, and F. chaus. Our domestic cat is probably the result of the crossing of the descendants of many distinct aboriginal stocks, which, as in the case of the dog, have not been known to breed together under natural conditions of life.

The parent form, or forms, from which our horses are descended, are not known with certainty; but the fact that in the Post-glacial epoch there were wild horses varying in size throughout Europe and Northern Asia, renders it very probable that the so-called Equus fossilis was the original progenitor. The animal first sprang into being in the Pleiocene Age, split off into varieties after the emergence of Europe from the glacial sea, and became the servant of man in the Neolithic or later Stone Age, during which two varieties were used by the dwellers in the Pfahlbauten. Since that time the varieties

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have gradually been multiplied, and the forms altered, by the care and attention of man. Like the dog, the horse can stand all the extremes of temperature and is spread nearly over the whole world.

'Aboriginally,' Mr. Darwin sagaciously observes (p. 53), 'the horse must have inhabited countries annually covered with snow, for he long retains the instinct of scraping it away to get at the herbage beneath. The wild Tarpans of the East have this instinct, and as I am informed by Admiral Sulivan, this is likewise the case with the horses which have run wild on the Falkland Islands; now this is the more remarkable as the progenitors of these horses could not have followed this instinct during many generations in La Plata.'

This very remarkable habit adds to the probability of the post-glacial origin of the domestic horse, which ranged through just those countries, in Europe and Asia, which were annually covered with snow. It is an open question whether the mouse-coloured horses still inhabiting the North Asiatic Steppes are the wild descendants of the aboriginal stock, or the descendants of runaways from man, as in America and Australia. Most naturalists incline to the latter opinion. The last notice of the wild horse in Europe is found in a remarkable list of graces of the Abbey of St. Galle, written between the years 980 and 1036:—

'Sit feralis equi caro dulcis in hac cruce Christi.'*

But in this case also there is no evidence of this horse not having been descended from a runaway. On the whole Mr. Darwin's conclusion from the study of the colour of different domesticated breeds is probably true:—

'The similarity in the most distinct breeds in their general range of colour, of their dappling, and in the occasional appearance, especially in duns, of leg-stripes, and of double or triple shoulder-stripes, taken together, indicate the probability of the descent of all the existing races from a single duncoloured, more or less striped, primitive stock, to which our horses still occasionally revert.' (P. 61.)

The horse in the service of man presents great and deep-seated variations from the equine type. In Paraguay, individuals are occasionally born with crisp woolly hair and short manes and tails, and hoofs shaped like those of the mule. Sometimes there are eight incisor teeth instead of six, at others an additional rib is developed. According to M. Gaudry they

* Benedict. ad Mensas Ekkehardi Monachi Sangallensis (Du Chesne), line 83.

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sometimes possess a trapezium, and a rudimentary fifth metacarpal, structures normally developed in the foot of the Hipparion, which is considered by that eminent naturalist to have been the Miocene ancestor of the horse.

The domestic cattle of Europe beyond all doubt have descended from at least two distinct wild forms—the gigantic urus quoted by Cæsar as being of a size little less than that of an elephant, and the small short-horn, Bos longifrons. Mr. Darwin, following Nillson and Rutimeyer, adds to these a third—Bos frontosus—which we cannot admit because it passes by insensible gradations gradually into the latter of these two animals. The urus boasts a far higher antiquity in Europe than the short-horn. During the Pleiocene epoch it dwelt in France and Italy, and before, as well as after, the Glacial period it was abundant in Britain. On the main land of Europe it was very numerous both in prehistoric and historic times, while in our own country insulated from the continent at the close of the Pleistocene epoch, it was exposed to exterminating causes that did not exist in the far larger area of the European mainland, and consequently it became very rare, and most probably was extinct as a wild species several centuries before it was driven away from the Hercynian Forest and the banks of the Danube. The first evidence of its domestication is afforded by the remains discovered in the pile-dwellings of Switzerland, which prove that before the use of bronze was known in central Europe, there was not only one domestic form but several varieties, probably formed by crossing. Thus in the Stone Age, the men who were the first to introduce the use of the dog and the horse into Europe, gave their attention to the breeding of cattle and to the formation of varieties. The wild animal, however, held its own ground in the forests of Switzerland and Germany, at least down to the tenth century, for it is mentioned in a vivid description of a great hunt held by Charlemagne in honour of the advent of the Persian ambassadors, as charging the Emperor, tearing his hose, and putting his suite to flight.* In Switzerland the monks of St. Galle returned thanks to God for its flesh as late as the eleventh century. At the close of the eleventh century it is mentioned along with the elk as being met with on the route through Germany taken by the first Crusade. For four centuries after this no mention is made of the animal, and if not extinct in Germany it must have become very rare.

* Monachi Sangallensis, lib. ii.; de Rebus Bellicis Caroli Magni, folio (Du Chesne) cap. xi.

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In regard to the second source of our domestic cattle, Bos longifrons, Mr. Darwin adopts Professor Owen's error, in ascribing to it an antiquity in Europe as far back as the time of the woolly mammoth, rhinoceros, and other extinct forms. That this view is untenable has amply been proved in the 'Quarterly Geological Journal' for 1867. The animal up to the present time has been found in no geological formation older than the comparatively modern alluvia and turbaries. Like the urus, the first evidence of its domestication is afforded by the remains found in the Swiss Pfahlbauten, belonging to the Stone Age. Throughout the ages of Bronze and Iron it was the principal food of the dwellers in France, Germany, Britain, and Italy. It is commonly associated in Britain with human remains of a date anterior to the coming of the Saxons. The tumuli studding the downs of Wiltshire are full of its bones, which occur almost universally also in the hut circles or dwelling places of the period. Around Roman stations and cities it is found in far greater abundance than any other animal, and especially in London and Colchester (Camulodunum). It must, therefore, have formed the principal part of the food of the coloni throughout the length and breadth of Roman Britain. Its sudden disappearance from all the parts of our country conquered by the Saxons is of very high historic interest, because it corroborates the view taken by Mr. Freeman, that the Saxon invader extirpated as far as he could everything Keltic and Roman. Along with the Kelt the animal was swept away, or so crossed and altered by the infusion of new blood in all parts of Britain that were conquered, that the type is only now to be found in the small black cattle of Wales, Cumberland, and Scotland, or exactly those parts whither the Keltic provincials fled for refuge. From the Saxon invasion the larger breeds of cattle begin to appear, most probably because the Saxons imported oxen from their old homes between the mouths of the Rhine and Jutland, which, according to Rutimeyer and Nillson, are descended from the great urus.

Mr. Darwin in treating of the selection of trifling characters by man, falls into a curious mistake:—

'With respect to cattle, an early record, according to Youatt, speaks of a hundred white cows with red ears being demanded as a compensation by the Princes of North and South Wales. If the cattle were of a dark or black colour a hundred and fifty were to be presented. So that colour was attended to in Wales before its sub-jugation by England.' (Vol. ii. p. 209.)

This passage by no means proves that the Welsh paid parti-

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cular attention to colour from motives of taste, but simply that they kept two breeds of oxen, the one the small black Bos longifrons, the other a much larger animal of the urus type, and closely allied to the Chillingham cattle. The possession of white bodies and red ears merely implies that the larger animals were to be sent, and not the smaller and less valuable.

It is not known with certainty whether Bos longifrons is indigenous in Europe, for there is no proof that the alluvia and turbaries, in which its remains occur, had been formed before the advent of the pastoral neolithic race of men. As, however, there never existed any European stock in a fossil state from which it could be derived, and as in that respect it is closely allied to the sheep and the goat, which are acknowledged to have been imported, it was probably introduced into Europe from that great pastoral district in the temperate zone, which Professor Draper terms 'the pathway of the nations,' and subsequently relapsed into a feral state, like the oxen and horses in America and Australia.

Mr. Darwin's inference, that the ancestors, whence our cattle were derived, dwelt in a warm or temperate climate, because the domesticated breeds do not possess the instinct of scraping away the snow to get at the herbage beneath, is corroborated by what we know of the habits of the urus and the Bos longifrons, the former of which belongs to the temperate group of the post-glacial mammalia, while the latter did not arrive in Europe until the arctic conditions of climate had passed away. From the crossing of these two animals all the various breeds of oxen in Central and Northern Europe are derived. In Italy the African buffalo has also been naturalised. The breeds in Africa and India are derived from various indigenous wild species, and in one instance at least have been known to breed freely with the European herds. The late Earl of Powis imported the zebu, and found it perfectly fertile with his cattle in Montgomeryshire.

New and distinct strains have been formed within modern times by care in selection and breeding. The Galloway polled cattle, for instance, have had an important part of their structure obliterated during the last hundred or eighty years. The Earl of Selkirk writes:—

'The breed a hundred and fifty years ago was not generally "polled," i.e. without horns, though there were always a good many polled ones among them. Polled ones are found in every breed. My informant was an old man who died about thirty years ago, he being then near ninety. He was the son of the man who tended the cows for my grandfather, and had been employed among cattle

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all his life; in his old age while still able to work he tended my cows. His name was James McKinnan, and he was a man whose recollections seemed always remarkably clear. He had been with cattle as far as Norfolk, to St. Faith's fair. He told me that in the days of his childhood, a Norfolk feeder, who bought many of the Galloway cattle, fancied those without horns, and would give 2s. 6d. or so more for a polled than for a horned beast. This set the fashion, and the people began first to look for polled bulls and none other; then they preferred the polled cows, &c. &c. to breed from, and thus the change was effected in, I believe, from fifty to sixty years. The horns of the Galloway beasts were very ugly, drooping, and as thick at the point as at the root. I have myself seen one or two beasts with horns like that; but nowadays when horns appear they are generally traced to some cross with an Irish brute. Those that are born polled have a bump in the centre of the forehead, which is very hard and will break another bull's skull for him.'*

The monstrous Niata breed from La Plata, quoted by Mr. Darwin, presents a variation among cattle analogous to that of the bulldog among the dogs, in the upward curvature of the maxillary and the projection of the mandible. It was first noticed in 1760, and as cattle were first imported into South America in 1552, it must have been formed in about two hundred years. The peculiarities are strongly transmitted to their descendants, and even to crosses with other breeds.

The domestic rabbit, from the rapidity with which it breeds, might be expected to show greater variation than the horse, dog, or ox; although, since the first evidence of its domesticity is afforded by the pages of Confucius, it has been under the dominion of man for a very much shorter time. It is considered by all naturalists, with the exception of Professor Gervais, to have descended from the common wild rabbit that has dwelt in Europe and Asia from the post-glacial epoch to the present day. During the two thousand years of its domestication it has been modified in a very remarkable degree, not only in enormous increase of size, or in the colour ot its fur, but also in its osseous framework. The large lopped-eared rabbit is not only much larger than its wild progenitor, but presents a differently shaped occipital foramen and zygomatic arch, with many other points of difference. In the half-lop the bilateral symmetry of the skull is destroyed. Mr. Darwin sums up the more important modifications as follows:—

'By the supply of abundant and nutritious food, together with little exercise, and by the continual selection of the heaviest individuals, the weight of the larger breeds has been more than doubled.

* Extract from a letter of the Earl of Selkirk, dated March 6th, Quart. Geol. Journ. Feb. 1867.

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The bones of the limbs have increased in weight (but the hind legs less than the front legs) in due proportion with the increased weight of body; but in length they have not increased in due proportion, and this may have been caused by the want of proper exercise. With the increased size of the body the third cervical vertebra has assumed characters proper to the fourth cervical; and the eighth and ninth dorsal vertebræ have similarly assumed characters proper to the tenth and posterior vertebræ. The skull in the larger breeds has increased in length, but not in due proportion with the increased length of body; the brain has not duly increased in dimensions, or has even actually decreased, and consequently the bony case for the brain has remained narrow, and by correlation has affected the bones of the face and the entire length of the skull. The skull has thus acquired its characteristic narrowness. From unknown causes the supra-orbital processes of the frontal bones and the free end of the molar bones have increased in breadth; and in the larger breeds the occipital foramen is generally much less deeply notched than in wild rabbits. Certain parts of the scapula and the terminal sternal bones have become highly variable in shape.' (Vol. i. p. 129.)

The evidence afforded by the study of domestic pigeons and fowls does not differ in kind from that of the rabbit. The peacock, however, affords proof that a bird so completely differing from its parents as to have been described under the name of a distinct species by Mr. Sclater, an eminent English ornithologist, may suddenly make its appearance. 'This black-shouldered or japanned variety' differs from the common peacock 'in the colour of the secondary wing feathers, scapulars, wing coverts, and thighs,' and breeds perfectly truly. There are five cases on record of its sudden appearance within the last fifty years:—

'Sir R. Heron states that this breed suddenly appeared within his memory in Lord Brownlow's large stock of pied, white, and common peacocks. The same thing occurred in Sir J. Trevelyan's flock, composed entirely of the common kind, and in Mr. Thornton's stock of common and pied peacocks. It is remarkable that in these two latter instances the black-shouldered kind increased "to the extinction of the previously existing breed." I have also received, through Mr. Sclater, a statement from Mr. Hudson Gurney that he reared many years ago a pair of black-shouldered peacocks from the common kind; and another ornithologist, Professor A. Newton, states that five or six years ago, a female bird, in all respects similar to the female of the black-shouldered kind, was produced from a stock of common peacocks in his possession, which during more than twenty years had not been crossed with birds of any other strain. Here we have five distinct cases of japanned birds suddenly appearing in flocks of the common kind in England. Better evidence of the first appearance of a new variety could hardly

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be desired. If we reject this evidence and believe that the japanned peacock is a distinct species, we must suppose in all these cases that the common breed had at some former period been crossed with the supposed P. nigripennis, but had lost every trace of the cross, yet that the birds occasionally produced offspring which suddenly and completely reacquired through reversion the characters of P. nigripennis. I have heard of no other such case in the animal or vegetable kingdom.' (Vol. i. pp. 290, 291.)

We can add a parallel instance of a like suddenness of variation in the case of pheasants in the Nynehead woods in Somersetshire, noted by Mr. W. Ayshford Sanford. Some thirty years ago, a single specimen of a variety differing from the common pheasant, in its pale brown, or dark cream-coloured tint, in the inferior brilliancy of the metallic glint on the head and neck, and in the shortness of its tail, was shot and stuffed. Two or three years afterwards, a dozen or more made their appearance in the same woods, and were all killed by the keepers, because they drove the other pheasants. The variety is known to most pheasant preservers as the Bohemian, a term which is synonymous most likely with gipsy, in the mouth of a keeper. There is no evidence of its occurrence out of Great Britain. Had it not been destroyed in this particular case, it would have taken possession of the wood and driven away the common pheasant. The sudden genesis of the japanned peacock and the Bohemian pheasant cannot be accounted for on Mr. Darwin's theory of selection. In the one there was no artificial, and in the other no natural selection, for there were no intermediate varieties observed; selection only came into play when the newly-formed variety began to compete with the parent form; which would, probably, in the case of the pheasant, have been extirpated on the Nynehead estate, had not Mr. Sanford preferred the normal breed. These two cases illustrate a very large class of facts which cannot be explained on Mr. Darwin's view of the preponderating share taken by selection in forming new varieties and species.

In the vegetable, as in the animal world, our knowledge has been gained by direct experience. All the vegetable productions that now minister to the need or luxury of man have been the result of the cultivation of wild species, combined with a careful selection of the best varieties thereby produced. There is no reason to suppose that any of our cultivated plants ever existed naturally in their present form; but, probably, all have been more or less modified. The wonderful stone-using folk who dwelt in the lakes of Switzerland, and who were the first to use the ox, horse, and dog, cultivated no less than

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'Ten cereal plants—namely, five kinds of wheat, of which at least four are commonly looked on as distinct species; three kinds of barley, a panicum, and a setaria. If it could be shown that at the earliest dawn of agriculture five kinds of wheat and three of barley had been cultivated, we should, of course, be compelled to look at these forms as distinct species. But as Heer has remarked, agriculture even at the period of the lake-habitations, had already made considerable progress; for besides the ten cereals, peas, poppies, flax, and apparently apples, were cultivated. It may also be inferred, from one variety of wheat being the so-called Egyptian, and from what is known of the native country of the panicum and setaria, as well as from the nature of the weeds which then grew mingled with the crops, that the lake-inhabitants either still kept up commercial intercourse with some southern people, or had originally proceeded as colonists from the South' … 'Heer gives an interesting account of the first appearance and final disappearance of the several plants which were cultivated in greater or less abundance in Switzerland during former successive periods, and which generally differed more or less from our existing varieties. The peculiar small-eared and small-grained wheat, already alluded to, was the commonest kind during the Stone period; it lasted down to the Helvetic Roman age, and then became extinct. A second kind was rare at first, but afterwards became more frequent. A third, the Egyptian wheat (T. turgidum), does not agree exactly with any existing variety, and was rare during the Stone period. A fourth kind (T. dicoccum) differs from all known varieties of this form. A fifth kind (T. monococcum) is known to have existed during the Stone period only by the presence of a single ear. A sixth kind, the common T. spelta, was not introduced into Switzerland until the Bronze Age. Of barley, besides the short-eared and small-grained kind, two others were cultivated, one of which was very scarce, and resembled our present common H. distichum. During. the Bronze Age rye and oats were introduced; the oat-grains being somewhat smaller than those produced by our existing varieties. The poppy was largely cultivated during the Stone period, probably for its oil; but the variety which then existed is not now known. A peculiar pea with small seeds lasted from the Stone to the Bronze Age, and then became extinct; whilst a peculiar bean, likewise having small seeds, came in at the Bronze period, and lasted to the time of the Romans.' (Vol. i. pp. 317–9.)

Thus, even at this remote epoch, by the combined labours of the archæologist and naturalist, a large number of the most useful vegetables are proved to have been under cultivation and to have varied in direct proportion to the increase of civilisation. But we are as ignorant of the wild progenitors of all these cultivated forms as we were before, for we do not know how long or in what country they were first cultivated. They have been so obscured by thousands of years of cultivation

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that they cannot be identified with certainty. With regard to oats, Mr. Buckman has proved that the wild English Avena fatua can be converted into forms strongly resembling those under cultivation. The plasticity of organisation of the wheats and barleys is shown most remarkably by the results of the careful selection of seeds by Mr. Hallet of Brighton, who has formed within the last few years several varieties, such as the famous pedigree wheat, deviating very considerably from the original stocks.

Among the fruits the peach is the most remarkable product of long-continued cultivation. Its descent from a sweet almond is inferred by Mr. Andrew Knight, from the fact of a sweet almond-seedling fertilised with peach-pollen yielding peaches.

'In France there is a variety called the peach-almond, which Mr. Rivers formerly cultivated, and which is correctly described in a French catalogue as being oval and swollen, with the aspect of a peach, including a hard stone surrounded by a fleshy covering, which is sometimes eatable. A remarkable statement by Mr. Luizet has recently appeared in the "Revue Horticole"—namely, that a peach-almond, grafted on a peach, bore during 1863 and 1864 almonds alone, but in 1865 bore six peaches and no almonds. M. Carrière, in commenting on this fact, cites the case of a double-flowered almond which, after producing during several years almonds, suddenly bore for two years in succession spherical fleshy peach-like fruits, but in 1865 reverted to its former state and produced large almonds.' (Vol. i. p. 338.)

The evidence brought forward by Mr. Darwin proves that there is a regular gradation from inferior peaches, 'through cling stones of poor quality to our best and most melting kinds,'—a fact that, coupled with the cases of sudden variation above recorded, renders it highly probable that the peach is the highly improved and modified descendant of the almond.

Whether we allow that the peach descended from the almond or not, we cannot help admitting that the nectarine is a variety of the peach, although it differs so remarkably from its parent form, that it is considered by M. Godron a distinct species. Mr. Darwin adduces evidence conclusive on the point:—

'Mr. Rivers states that from stones of three distinct varieties of the peach he raised three varieties of the nectarine; and in one of these cases no nectarine grew near the parent peach-tree. In another instance Mr. Rivers raised a nectarine from a peach, and in the succeeding generation another nectarine from this nectarine. Other such instances have been communicated to me, but they need not be given. Of the converse case, namely, of nectarine stones yielding peach-trees, both free and cling-stones, we have six undoubted instances recorded by Mr. Rivers; and in two of these instances the

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parent nectarines had been seedlings from other nectarines. … Peter Collinson in 1741 recorded the first case of a peach-tree producing a nectarine, and in 1766 he added two other instances. In the same work (the "Correspondence of Linnæus", 1821) the editor, Sir J. E. Smith, describes the more remarkable case of a tree in Norfolk, which usually bore both perfect nectarines and perfect peaches; but during two seasons, some of the fruit were half and half in nature.' (Vol. i. p. 340.)

These remarkable facts cannot be accounted for by reversion to an original form, for in that case the nectarine ought to revert more often to the peach than the peach to the nectarine. Nor can they be explained by the hypothesis that the parent forms were in every case hybrid, and that the hybridity had lain dormant up to the time of the bud-variation, for six well-known different varieties, in different places, yielded the same result. Nor can they be ascribed to the fertilisation of the peach by the pollen of the nectarine, because a branch that has once produced nectarines has been known to continue to produce them for several years, and could hardly have been fertilised without the other branches also being similarly affected. Similar instances of bud-variation are presented by grapes, apples, and very many plants such as the rhibes, purple thorn, pelargonium, Sweet William, and others, that cannot be accounted for on any current hypothesis. In some cases, however, the bud-variation reverts to the original form, as in the oak-leaf laburnum, the parsley-leaved vine, the fern-leaved beech, and others.

'With seedlings raised from the more variable cultivated plants, the variations are almost infinitely numerous, but their differences are generally slight; only at long intervals of time a strongly marked modification appears. On the other hand, it is a singular and inexplicable fact that, when plants vary by buds, the variations, though they occur with comparative rarity, are often, or even generally, strongly pronounced. It struck me that this might perhaps be a delusion, and that slight changes often occurred in buds, but from being of no value were overlooked or not recorded. Accordingly, I applied to two great authorities on this subject—namely, to Mr. Rivers with respect to fruit-trees, and to Mr. Salter with respect to flowers. Mr. Rivers is doubtful, but does not remember having noticed very slight variations in fruit-buds. Mr. Salter informs me that with flowers such do occur, but, if propagated, they generally lose their new character in the following year; yet he concurs with me that bud-variations usually at once assume a decided and permanent character.' (Vol. i. p. 410.)

The phenomenon of bud-variation is precisely analogous to the sudden appearance of the japanned peacock and Bohe-

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mian pheasant in the animal kingdom, and both are probably due to the same mysterious cause. In both the direct action of the external conditions of life appears 'to have played a quite subordinate part, of not more importance than the nature of the spark which ignites a mass of combustible matter.'

In these examples of Mr. Darwin's method of studying the origin and growth of each domestic species, it is impossible to deny the learning and ability with which he has approached the subject. That the facts are as he states them to be, there can be no doubt. We have now to discuss the principles based upon them. The first to be noticed is that of artificial selection. Mr. Darwin proves that the art has been practised since the very dawn of history:—

'In a well-known passage in the thirtieth chapter of Genesis, rules are given for influencing, as was then thought possible, the colour of sheep; and speckled and dark breeds are spoken of as being kept separate. By the time of David the fleece was likened to snow. Youatt, who has discussed all the passages relating to breeding in the Old Testament, concludes that at this early period "some of the best principles of breeding must have been steadily and long pursued." It was ordered, according to Moses, that "Thou shalt not let thy cattle gender with a diverse kind;" but mules were purchased, so that at this early period other nations must have crossed the horse and the ass. It is said that Erichthonius, some generations before the Trojan war, had many brood-mares, "which by his care and judgment in the choice of stallions, produced a breed of horses superior to any in the surrounding countries." Homer, book v., speaks of Æneas' horses as bred from mares which were put to the steeds of Laomedon. Plato in his "Republic" says to Glaucus, "I see that you raise at your house a great many dogs for the chase. Do you take care about breeding and pairing them? Among animals of good blood, are there not always some which are superior to the rest?" to which Glaucus answers in the affirmative. Alexander the Great selected the finest Indian cattle to send to Macedonia to improve the breed. According to Pliny, King Pyrrhus had an especially valuable breed of oxen; and he did not suffer the bulls and cows to come together till four years old, that the breed might not degenerate.' (Vol. ii. pp. 201, 202.)

At the present day there is scarcely any savage tribe by which selection is not more or less practised. Even the Fuegians take pains to pair the finest of their dogs together to produce as fine and healthy a breed as possible. The most insignificant characters have been valued by ancient and semi-civilised peoples. Xenophon proscribed slate-coloured and white hunting dogs. The gourmands of ancient Rome preferred the liver of a white goose, and at the present day the Kaffirs admire the musical low of a heifer.

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It is impossible not to attribute to selection, thus carried on during enormously long periods, very great power in the formation of new breeds, but Mr. Darwin goes too far when he writes, ' whenever and wherever selection is not practised, distinct races are not formed.' So far from this being true, there are many instances of the genesis of varieties or races without any selection whatever. What share, for instance, could it have had in the origin of the japanned peacock and Bohemian pheasant; or in the many recorded cases of budvariation, or in the growth of a nectarine from the stone of a peach? It must be admitted, therefore, that there are principles at work in the formation of breeds and varieties other than that of selection. Mr. Darwin subsequently qualifies this statement by ascribing to selection 'a paramount power' only, and bases its action 'on what we in our ignorance call 'spontaneous or accidental variability':—

'Let an architect' (he writes), 'be compelled to build an edifice with uncut stones fallen from a precipice. The shape of each fragment may be called accidental, yet the shape of each has been determined by the force of gravity, the nature of the rock, and the slope of the precipice, events and circumstances all of which depend on natural laws; but there is no relation between these laws and the purpose for which each fragment is used by the builder. In the same manner the variations of each creature are determined by fixed and immutable laws; but these bear no relation to the living structure, which is slowly built up through the power of selection, whether this be natural or artificial selection.' (Vol. ii. p. 248.)

In this passage we fail to see the parallel between a block of stone lying at the foot of a precipice and the variation presented by a plant or animal. In the building the individual stones are removed from the parent rock and used according to the taste of the builder; in the breed the variations are not isolated from the form in which they are manifested, nor can they be used as the breeder chooses. They cannot be looked upon as so many independent entities, but as some only of the many phenomena manifested in each individual Nor can we understand the argument, that because the stones in question are shaped in dependence on natural laws, therefore variations are determined by fixed and immutable laws, bearing no relation to the living structure. How, moreover, can an ignorance of the laws of variation be combined with the knowledge that they are fixed and immutable? Mr. Darwin has clearly been led astray by his attachment to the building metaphor, which he reproduces at the end of his work.

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Variation has at least a co-ordinate power with selection in the formation of varieties in breeds. In the four chapters treating of this subject the only principle that can be considered fully established is that excess of nutriment, or change in conditions of life in the parent forms, cause variability, which however is frequently not manifested for several generations. Turkeys raised from the eggs of wild species lose their metallic tints in the third generation and become spotted with white:—

'An excellent observer, who has often reared birds from the eggs of the wild duck, and who took precautions that there should be no crossing with domestic birds, has given, as previously stated, full details on the changes which they gradually undergo. He found that he could not breed these wild ducks true for more than five or six generations, "as they then proved so much less beautiful. The white collar round the neck of the mallard became much broader and more irregular, and white feathers appeared in the duckling's wings." They increased also in size of body; their legs became less fine, and they lost their elegant carriage.' (Vol. ii. p. 262.)

This generally holds good also in the case of flowers. The zinnia after several years' culture only began to vary in 1860, while the Swan River daisy varied after seven or eight years of very high cultivation. In these and the like cases the variability apparently is the direct result of a change in the conditions of life, the effect of which has gradually accumulated until at last the constitution of the plant or animal has broken down.

Variation is in some cases directly traceable to the use or disuse of parts. Thus in the domestic duck the wings weigh less, and the legs more, in proportion to the whole skeleton, than do the same bones in the wild duck. The brain of the domestic rabbit weighs less relatively to the whole body than in the wild animal, because it is not compelled to use its faculties in the acquisition of food:—

'It is well known that several animals belonging to the most different classes, which inhabit the caves of Styria and of Kentucky, are blind. In some of the crabs the foot-stalk for the eye remains, though the eye is gone; the stand for the telescope is there, though the telescope with its glasses has been lost. As it is difficult to imagine that eyes, though useless, could bo in any way injurious to animals living in darkness, I attribute their loss wholly to disuse.' (Origin of Species, p. 137.)

There are no reasons for supposing that selection, either natural or artificial, had anything to do with any of these cases.

With regard to bud-variation, Mr. Darwin halts between

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two opinions. In the 'Origin of Species' (p. 131) he attributes for the most part the varying or plastic condition of the offspring to a functional disturbance in the reproductive system of the parents. 'The male and female sexual elements seem to be affected before that union takes place which is to form a new being. In the case of sporting plants the bud, which in its earliest condition does not essentially differ from an ovule, is alone affected.' In this passage he implies that there is no radical physiological difference between the ovule and the bud. On the other hand, in the work under consideration, he writes (vol. ii. p. 267):—'It is at least clear that in all cases of bud-variation the action cannot have been through the reproductive system.' He reverts to the former of these views, which probably is the true one, in his chapter containing the provisional theory of pangenesis.

Although the precise cause of variation in this or that organ cannot be pointed out, it is, on the whole, fair to assume that it is identical with that which gives to each individual those differences by which he is separated from his fellows, and which are either inherited or the result of the direct action of the external conditions. Mr. Herbert Spencer forcibly argues that variation must take place by the law of the persistence of force:—

'The members of a species inhabiting any area cannot be subject to like aggregates of forces over the whole of that area. And if, in different parts of the area, different kinds, or amounts, or combinations of forces act on them, they cannot but become different in themselves, and in their progeny. To say otherwise is to say that differences in the forces will not produce differences in the effects; which is to deny the persistence of force. Whence it is also manifest that there can be no variation of structure, but what is directly or indirectly consequent on variation of function. On the one hand, organisms in complete equilibrium with their conditions, cannot be changed except by change in their conditions, since to assert otherwise is to assert that there can be an effect without a cause; which is to deny the persistence of force. On the other hand, any change of conditions can affect an organism only by changing the actions going on in it—only by altering its functions. The alterations of functions being necessarily towards a reestablishment of the equilibrium (for if not the equilibrium must be destroyed and the life cease, either in the individual or in the descendants), it follows that the structural alterations directly caused are adaptations; and that the correlated structural alterations indirectly caused are the concomitants of adaptation. Hence, though by the intercourse of organisms that have been functionally and structurally modified in different directions, there may result organisms that deviate in compound ways which appear unrelated to external conditions, the deviations of such organisms must still be regarded as indirect results

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of functional adaptations. We must say that in all cases adaptive change of function is the primary and ever-acting cause of that change of structure which constitutes variation; and that the variation which appears to be "spontaneous" is "derivative and secondary."' Principles of Biology, vol. i. p. 271.)

Whether this view be held as proved or not, it explains the phenomena of variation far better than the view taken by Mr. Darwin, that 'in most cases the conditions of life play a subordinate part in causing any particular modification;' while in the case of bud-variation and of the sudden appearance of offspring unlike the parents, which he is content to look upon as inexplicable, 'accidental or spontaneous,' it supplies an adequate cause for the results produced. The fact that peaches, nectarines, apricots, roses, and camellias under cultivation have yielded closely analogous bud-varieties, would imply some one cause affecting all pretty much in the same way; that is to say, a constitutional change brought about by unnatural conditions of life. But, whatever view we take of variation, we must admit that in some cases it can produce a variety or breed without the intervention of selection, and that therefore it by no means occupies the subordinate position which is assigned to it by Mr. Darwin among the causes of the appearance of new forms of life.

The principle of heredity also has at least a co-ordinate power with variation and selection:—

'It is hardly possible, within a moderate compass, to impress on the mind of those who have not attended to the subject, the full conviction of the force of inheritance which is slowly acquired by rearing animals, by studying the many treatises which have been published on the various domestic animals, and by conversing with breeders. I will select a few facts of this kind which, as far as I can judge, have most influenced my own mind. With man and the domestic animals, certain peculiarities have appeared in an individual, at rare intervals, or only once or twice in the history of the world, but have reappeared in several of the children and grandchildren. Thus Lambert, the "porcupine-man," whose skin was thickly covered with warty-projections, which were periodically moulted, had all his six children and two grandsons similarly affected.' (Darwin, vol. ii. p. 4.)

Gait, gestures, handwriting, features, colour, disease, and the like are transmitted faithfully to the offspring. The art of horse-breeding depends altogether on the force of inheritance. The English racehorse, for instance, invariably inherits his vigour and endurance from his ancestors:—

'Eclipse begot 334, and King Herod 497, winners. A cock-tail is a horse not purely bred, but with only one-eighth or one-sixteenth

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impure blood in his veins, yet very few instances have ever occurred of such horses having won a great race. They are sometimes as fleet for short distances as thoroughbreds, but as Mr. Robson, the great trainer, asserts, they are deficient in wind and cannot keep up the pace. Mr. Lawrence also remarks, "perhaps no instance has occurred of a three-part bred horse saving his distance in running two miles with thoroughbred racers." It has been stated by Cecil, that when unknown horses, whose parents were not celebrated, have unexpectedly won great races, as in the case of Priam, they can always be proved to be descended on both sides, through many generations, from first-rate ancestors. On the Continent Baron Cameronn challenges, in a German veterinary periodical, the opponents of the English racehorse to name one good horse on the Continent which has not some English race-blood in his veins.' (Vol. ii. p. 11.)

The power of direct inheritance is, however, sometimes overborne by atavism or reversion, in which the plant or animal does not resemble the parent form so much as that of an ancestor more or less remote. For instance, in variously coloured pure breeds of pigeons, the characteristic plumage of the wild rock pigeon occasionally appears. In the hornless breed of cattle the ancestral horns are sometimes developed. A reversion to the ancient dark or tawny colour is frequently seen in all breeds of sheep. In the vegetable world also,

'by the aid of a little selection carried on during a few generations, most of our cultivated plants could probably be brought back, without any great change in the conditions of life, to a wild or nearly wild condition. Mr. Buckman has effected this with the parsnip; and Mr. Hewitt C. Watson, as he informs me, selected during three generations "the most diverging plants of Scotch kail, perhaps one of the least modified varieties of the cabbage;" and in the third generation some of the plants came very close to the forms now established in England about old castle walls and called indigenous.' (Vol. ii. p. 31.)

Mr. Darwin takes very just exception to the general assumption that domesticated plants and animals which have run wild invariably revert to their primitive specific type. There are many cases that disprove its truth. Feral rabbits, in Jamaica and Porto Santo, assume new colours and new characters, instead of reverting to their wild progenitor of Europe and Asia. The guinea-fowl, naturalised in the West Indies, varies more than in the domestic state. Pigs

'have run wild in the West Indies, South America, and the Falkland Islands, and have everywhere acquired the dark colour, the thick bristles, and great tusks of the wild boar; and the young have reacquired longitudinal stripes. But even in the case of the pigs, Roulin describes the half-wild animals in different parts of South

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America as differing in several respects. In Louisiana the pig has run wild, and is said to differ a little in form and much in colour from the domestic animal, yet does not closely resemble the wild boar of Europe.' (Vol. ii. p. 33.)

While therefore we must admit that there is a tendency in all these cases to revert to an ancestral type, there is no proof that it has been fully carried out. The characters acquired by long domestication being in no case wholly lost, and the variability caused by the change from feral to cultivated conditions of life being maintained after the change from the domestic to the feral.

Reversion is often caused by intercrossing two breeds. Thus the Himalayan breed of rabbits, with its snow-white body, black ears, nose, tail, and feet, formed by the union of two varieties of silver-greys, contrary to what is generally received on the subject, breeds perfectly truly. When crossed with a sandy-coloured buck the progeny reverts to the silvergrey variety. Not only lost characters but lost instincts may be recovered by crossing. The breeds of fowls called the everlasting layers have lost the instinct of incubation, but when two of these are crossed the result is a mongrel that, according to the great authority of Mr. Tegetmeier, becomes 'broody and sits with remarkable steadiness.'

The hybrids of our domestic animals reproduce the instincts of the primitive wild stocks in a remarkable degree. The descendants of the Indian zebu, crossed by the late Earl of Powis with English cattle, were extraordinarily wild. Mules are notoriously obstinate and vicious. The progeny of the musk and common duck exhibit migratory propensities. Mr. Darwin applies this principle of reversion to the explanation of the savage and brutal character of crossed races of men.

'Many years ago, long before I had thought of the present subject, I was struck with the fact that, in South America, men of complicated descent between Negroes, Indians, and Spaniards seldom had, whatever the cause might be, a good expression. Livingstone—and a more unimpeachable authority cannot be quoted—after speaking of a half-caste man on the Zambesi, described by the Portuguese as a rare monster of inhumanity, remarks, "It is unaccountable why half-castes such as he are so much more cruel than the Portuguese, but such is undoubtedly the case." An inhabitant remarked to Livingstone, "God made white men, and God made black men, but the Devil made half-castes." When two races, both low in the scale, are crossed, the progeny seems to be eminently bad. Thus the noble-hearted Humboldt, who felt none of that prejudice against the inferior races now so current in England, speaks in strong terms of the bad and savage disposition of Zambos, or half-

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castes between Negroes and Indians; and this conclusion has been arrived at by various observers. From these facts we may perhaps infer that the degraded state of so many half-castes is in part due to reversion to a primitive and savage condition, induced by the act of crossing, as well as to the unfavourable moral conditions under which they generally exist.' (Vol. ii. p. 46.)

All the highly complex phenomena presented by plants and animals under domestication fall naturally under these three great principles—selection, variation, and heredity—which may be viewed as a trinity of causes, in which variation sometimes acts without selection. There seems to be full evidence that external conditions of life operating on slightly different individuals, cause them to vary in different degrees and directions; that these variations are transmitted in accordance with the laws of heredity, and become more or less firmly stamped on each organism; and lastly, that selection merely gives a definite direction to variations thus impressed on the constitution of each plant and animal. In this way the formation of each breed and variety is brought about. Mr. Darwin gives an undue prominence to selection, and degrades the two other principles to a much lower position, although when treating of them separately he is compelled to recognise their true value.

We can give merely a faint outline of the bearing of variation under domestication on the origin of species, because Mr. Darwin reserves its discussion for a future work. We have seen that three great principles lie at the root of all the phenomena presented by plants and animals under the dominion of man, two of which—heredity and variation—are inseparable from life itself. Is the third, or selection by which breeds arise, identical in kind with natural selection, to which Mr. Darwin ascribes the origin of species? At first sight there appears to be this difference, that by one the variations are guided according to the will of man, by the other for the well-being of the individual in the struggle for life which is incessantly going on in nature. This difference is also shown in the appearance of monstrous forms under domestication, such as the hairless and edentulous dogs, poodles, and the like, which could not have existed under natural conditions. Apart from this difference of end, there seems to be none other. Man takes a plant or animal out of the province of natural selection, by which its variations were curbed and restrained according to its environment, and substitutes for that principle his own will and pleasure; he merely developes the capacity for adaptation to external circumstances by a sudden change in the condition of life, but he does not create that capacity. All

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naturalists are agreed that there are natural varieties caused in some cases by the direct influence of external conditions of life. The restricted range, for instance, of the Singalese elephant has left its mark in the small development of the tusks as compared with those of the Indian peninsula. Baron Cuvier himself admits the very principle for which Mr. Darwin and M. I. G. Saint-Hilaire contend when he writes,* that domestication 'développetoutes les variations dontle type de chaque espèce est suceptible, et en tire des produits que les espèces, livrées à elles-mêmes n'auraient jamais donné.' That is to say, that there is a latent power of variation in each species. The study of domestic productions, therefore, shows to what extent this may be developed, and therefore has a very important bearing on the origin of species.

It is undoubtedly true that in nature the pronounced variations visible under domestication are absent; but, on the other hand, it is equally true that there is no sudden change of external conditions to produce them. The breed is frequently of equal classificatory value with the species, as, for instance, in the case of pigeons, cattle, and the like. The test of breeding does not even afford a means of definition; for, on the one hand, the feral Porto Santo rabbits refuse to breed with their tame English progenitors; while, on the other hand, in the vegetable world, some species, such as Cactus, Salix, Saxifraga, are even admitted by Linnæus to be capable of crossing. There is therefore a parallel between breeds and species, and it may be fairly argued that as the one is the product of the operation of artificial selection on heredity and variation, so the other may have been formed by a like operation of natural selection on the same principles.

There is another point of view from which the mutability of species may be examined. All the varied forms of life in the world around us are exquisitely adapted to the external conditions, which either remain unchanged, or change so slowly as to escape notice. An appeal to the earth's crust proves that the latter have been constantly changing; continents have been elevated and depressed, climates altered; at one time the sea has encroached on the land, at another the land on the sea—

'There rolls the deep where grew the tree.
Oh, earth! what changes hast thou seen:
There where the city roar hath been,
The stillness of the central sea.'

* Discours sur les Révolutions, Oss. Foss. tom. i. p. 61. 4to. 1825.

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With each change of circumstance there is full geological proof that there has been a corresponding modification in the animal and vegetable world, so that the harmony between life and its environment has always been maintained. The common red deer, for instance, at the time when Britain formed part of the mainland of Europe, during the Post-glacial epoch, in consequence of the large extent of its feeding-grounds, grew to an enormous size, and possessed antlers so much larger than those now borne by the English varieties, that Professor Owen did not hesitate to ascribe it to a distinct species* (Strongylocerus spelœus). During prehistoric times, after the insulation of Britain and the consequent submergence of the low-lying districts, the restricted range is manifested in its diminished size; but even then it was far superior to any now living in Great Britain, for the cultivated lands were but oases in one large forest. From that time down to the present, it has been growing smaller exactly in proportion to the restriction of its area. The difference in the size of the antlers is so marked, that it would be possible to ascertain approximately the antiquity of a deposit in which they might be found, from that fact alone. There is also another cause of its reduction in size. During post-glacial times men were few, and the lion and hyæna preyed only on the weakest and less active: while in the prehistoric period man increased and multiplied to such a degree that he made an impression on the wild animals, and, as far as he could, selected the largest and finest for his prey. At the present day, in Scotland, it is steadily deteriorating in size, because the largest bucks are invariably shot off. In this case there is a direct correlation between the size of the animal and its environment, from the Post-glacial epoch down to the present day.

If we deny that change of conditions operating on the latent power of adaptation is a cause adequate to the making of new groups of animals, we must fall back upon the theory that the latter have been created from time to time in harmony with the external conditions from the very beginning of things. But if this be true, how can we account for the destructions of old forms of life? The cataclysms and convulsions of nature, that were formerly invoked to the aid of the special creation theory, have now been banished from the schools of philosophic geology. A sudden destruction, overtaking the whole of a fauna or flora, is unknown in the past history of the world. The horse, urus, and Elephas antiquus, for instance, that inhabited France,

* Brit. Foss. Mammals.

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Germany, Italy, and Britain, escaped the destruction brought upon their fellows by the lowering of the temperature, and the concomitant invasion of the reindeer, musk-sheep, and other Arctic mammalia. Their survival can only be accounted for on the hypothesis that their elasticity of constitution adapted them to the new order of things; while certain species of rhinoceros and elephant, and many species of deer, became extinct because they were not able to modify their habits so as to become in harmony with the new conditions of life. To say with M. Lartet,* that species disappear 'en conformité sans doute des lois qui, en réglant la longévité des individus, limitent en même temps la durée des espèces,' is to leave the problem unsolved and hampered with a very wide question, as to whether its life obeys the same laws as that of the individual. Few would be prepared to explain this class of facts by the assumption that at stated times the destroyer walks over the whole earth, choosing out species for extermination. Yet we must admit this if we adhere to the theory of special creation.

So far as our experience goes, change of conditions whether natural or artificial must cause corresponding change in the individual. If a variety of elephant can be formed by the insulation of Sumatra and Ceylon from the mainland of Asia, sufficiently marked to cause Schlegel to consider it distinct from the Indian species, in the short time, geologically speaking, that has elapsed since those two islands formed part of the same continent, can we venture to assert that no lapse of time and no further changes in condition would suffice to widen and deepen the chasm between the species and the variety, until the latter ranked also as a species? This is really what the believers in the invariability of species assume. They ask us to believe that because slight modification in the environment during the fleeting life of man produces only slight varietal modifications in the individual, greater changes in the environment operating on the individual during an inconceivably long period could not produce any greater effect. The fallacy of this argument it is unnecessary to point out. As plants and animals now invariably live in exact harmony with their external conditions, and exhibit a power of variation in exact proportion to slight modifications in them, the inference may fairly be drawn that in past time the magnitude of the variation corresponded to the magnitude of the change in their external conditions, or, in other words, that the cause which

* Comptes Rendus, 1858, p. 413.

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produces a variety in limited time, in unlimited is adequate to the production of a species.

If this be true, we ought to find among the scraps and tatters of former faunas and floras, stored up in the rocks, intermediate forms to bind together divergent species and genera. It has usually been assumed that such forms do not exist; their existence, however, has been placed beyond all doubt by recent discoveries, and especially by those of M. Gaudry* in the Upper Miocene strata of Pikerni on the plains of Marathon. In the case of the Quadrumana, a fossil monkey (Mesopithecus Pentelici) links together the two genera Macacus and Semnopithecus. In the Carnivora, the family of the hyæna and that of the weasel, at the present day widely divergent, are connected by three distinct genera (Lychyœna, Hyœnictis, and Ichtiherium). The wolf and the bear by the Metarctos diaphorus. Although there is little outward resemblance between the existing birds and reptiles, their inner affinities are known to every comparative anatomist. The chasm between them is to a certain extent bridged over by the discoveries in the Solenhofen slates. On the one hand, the extraordinary fossil bird, archæopteryx, is more reptilian in character than any now alive, having feathers and other characters of a bird, combined with the tail of a reptile. From the same formation a remarkable reptile has been derived, more bird-like than any with which we are now acquainted. 'It is impossible,' writes Professor Huxley, 'to look at the conformation of this strange reptile, and to doubt that it hopped or walked in an erect or semi-erect position, after the manner of a bird, to which its long neck, slight head, and small anterior limbs must have given it an extraordinary resemblance.'* The whole Deinosaurian class is proved by the same eminent authority to have been more ornithic in character than any existing reptiles. Intermediate forms are undoubtedly few and far between; but could we expect them to be otherwise? A very small portion of the animal or vegetable kingdom chances to become entombed in the rocks, and to be

* Animaux Fossiles et Géologie de l'Alligne, Part I. Animaux Fossiles, livraisons 1–16. 4to. 1862–7. M. Gaudry has based his conclusions in this magnificent work for the most part on variations in the number and form of the teeth, and in the form of the bones. It is the most philosophical exposition of an extinct fauna that has yet been published. See Quart. Journ. Geolog. Soc. vol. xxiv. Part I. Memoirs, p. 1.

* Lecture at the Royal Institution of Great Britain, Friday, Feb. 7, 1868.

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thus preserved for future time. The rocks themselves are exposed to the incessant wear and tear of the waves and of the streams and atmosphere from the very moment they become dry land. A very small area, moreover, of the earth's surface has been scientifically explored. From these three causes intermediate forms must necessarily be scarce. Again, two consecutive formations do not represent an unbroken sequence of time, but epochs indefinitely removed from each other, and they contain suites of fossils distinct from each other, in proportion to the length of the interval between the times of their deposition. As therefore an unbroken sequence of time is not represented in the rocks, we cannot expect to find a perfect series of gradations between any one living species and its fossil ancestors. The evidence therefore of intermediate forms, so far as it goes, is corroborative of the hypothesis that species are transmutable, and that all the varied forms of life now on the earth are lineally descended from ancestors which have varied exactly in proportion to the change in their external conditions. Additional proof tending in the same direction may be obtained from the classification and distribution of plants and animals which Mr. Darwin reserves for a future work. Whether his views be accepted or not, it must be admitted that he has given a most valuable impulse to the 'philosophical investigation of the most backward and obscure branch of the biological sciences of the day,'* by his careful researches and earnest writings. In all probability the naturalists of the future, while endorsing his principle, will deny to selection the paramount power with which it is invested in his theory of evolution.

Mr. Darwin concludes with an attempt to account for the obscure facts presented by reproduction, heredity, and variation, by the following hypothesis, which is very likely to be true, although it is not capable of direct proof:—

'It is almost universally admitted that cells, or the units of the body, propagate themselves by self-division or proliferation, retaining the same nature, and ultimately becoming converted into the various tissues and substances of the body. But besides this means of increase, I assume that cells, before their conversion into completely passive or "formed material," throw off minute granules or atoms, which circulate freely throughout the system, subsequently becoming developed into cells like those from which they were derived. These granules, for the sake of distinctness, may be called cell-gemmules, or, as the cellular theory is not fully established, simply gemmules. They are supposed to be transmitted from the

* Falconer's Memoirs, vol. ii. p. 254.

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parent to the offspring, and are generally developed in the generation which immediately succeeds, but are often transmitted in a dormant state during many generations, and are then developed. Their development is supposed to depend on their union with other partially developed cells or gemmules which precede them in the regular course of growth. … Gemmules are supposed to be thrown off by every cell or unit not only during the adult state, but during all stages of development. Lastly, I assume that the gemmules in their dormant state have a mutual affinity for each other, leading to their aggregation either into buds or into the sexual elements. Hence speaking strictly, it is not the reproductive elements nor the buds which generate new organisms, but the cells themselves throughout the body. These assumptions constitute the provisional hypothesis which I have called Pangenesis.' (Vol. ii. p. 374.)

Similar views to these had already been advanced by Mr. Herbert Spencer in 1863.† The existence of free gemmules, or physiological units as they are called by the latter author, 'is a gratuitous assumption,' but can hardly be considered improbable, since it is universally admitted that cells have the power of multiplication through the self-division of their contents. An atom of small-pox poison inconceivably minute is able to affect the whole blood by self-multiplication. By the same process also, an atom of diseased matter from an animal affected with rinderpest, increases so fast, 'that in a short space of time the whole mass of blood, weighing many pounds,' is infected in the body of a healthy animal. When we remember how long seeds lay dormant in the earth, the idea that these free gemmules may remain dormant in the organism, is not so improbable as it appears at first sight. Their minuteness and numbers, rendered necessary by the hypothesis, is no stumbling-block to its being accepted. The common Ascaris lumbricoides, according to Dr. Carpenter, has been known to contain no fewer than sixty-four million ova at one time. The revelations of the microscope prove that size is merely comparative and depending upon our powers of vision. In the case of odours, such as musk and assafœtida, small atoms may be given off for a long period, without causing any visible diminution of the bulk. The gemmules must be thoroughly diffused throughout the body, and must possess an 'elective affinity' or 'polarity' for those particular cells that precede them in order of development. If we cut off the tail of a lizard, a fresh tail buds forth and passes through all the stages of development until it acquires its perfect form; a fact that can only be explained by the hypothesis that there exists in the

† Principles of Biology, vol. i.

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whole body gemmules thrown off by each individual cell in the lost tail, and capable of assuming the same position in the new one as the parent cells in the old. A common polyp may be cut to pieces, and each fragment will form the basis of growth for a fresh individual. From a scrap of begonia leaf stuck in the ground, a whole plant is capable of being formed. In the case of abnormal growths, the elective affinity of the first set of gemmules has changed in such a way as to cause them to combine with others of a different kind; and when this combination has been once effected, the aggregation of the succeeding ones is carried on as if their predecessors occupied their normal positions. The growth of hairs in the brain, and of teeth in ovarian tumours, or in the orbit of the eye, can only be explained on this hypothesis. No one can deny that the various tissues possess an affinity for certain organic substances. The kidney cells attract urea from the blood, the nerves are affected by worrara, the muscles by upas, digitalis, and the like. If, then, each cell possess certain affinities, the gemmule or hypothetical offspring of that cell must possess them to a greater or less degree.

There seems to be sufficient evidence that each cell in the body has a quasi-independent existence; the spur of a cock inserted into the eye of an ox, lived for eight years, and acquired a weight of nearly fourteen ounces. The tail of a pig has been grafted into the middle of its back, and that belonging to a rat into the cartilage of its nose, and both have reacquired sensibility. A strip of periosteum from the bone of a young dog placed under the skin of a rabbit has been known to develope true bone.

Let us now see how this theory accounts for other classes of facts. All the forms of reproduction graduate into each other. According to Professors Huxley and Clark, fission is little more than a peculiar mode of budding. That the union of two sexual elements is not indispensable, is proved by the well-known facts of parthenogenesis. Ovules and buds are admitted to have the same essential nature by the high authority of J. Müller. In M. Jourdain's experiment on 5,800 eggs, laid by unimpregnated silkmoths, many passed through their embryonic stages and thus showed that they were capable of self-development; but of the whole number only twenty-nine produced caterpillars. From these and the like cases it is clear that the belief in the function of the spermatozoa to communicate life to the ovule is groundless. The phenomenon of budding in the lower animals, such as the medusæ, proves that the belief that the sexual elements are created by the

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reproductive organs is equally unfounded. All these facts are rationally explained by the doctrine of Pangenesis. It also accounts satisfactorily for the facts that the offspring is more or less like the parents, and yet sometimes more like an ancestor. That the gemmules have a power of remaining latent is proved by male characters handed down through the female, from the grandfather to the grandson, as well as by the inheritance of certain diseases peculiar to one, through the opposite sex. There appears, indeed, to be evidence that every character that occasionally reappears is present in a latent form in each generation. On this theory each individual contains gemmules of his ancestors on each side, which are capable of manifesting themselves according to their prepotency.

The transmission of variations is unaccountable by the current views of reproduction. How, for instance, can the use or disuse of particular organs be inherited unless it be through the gemmules of that organ? 'A horse is trained to certain paces, and a colt inherits similar consensual movements.' The offspring of dogs taught to beg have been known to beg without any teaching. The legs of the domestic duck have increased in size while its wings have decreased as compared with those of its wild ancestor. 'How,' Mr. Darwin pertinently asks, 'can the use or disuse of a particular limb, or of the brain, affect a small aggregate of reproductive cells, seated in a distant part of the body, in such a manner that the being developed from those cells inherits the character of either one or both parents?' To this question the theory of Pangenesis affords an imperfect answer.

This theory is one that can be neither proved nor disproved, but may be considered true in exact proportion as it explains the facts. According to it each plant and animal 'may be compared to a bed of mould full of seeds, most of Which soon germinate, some lay for a period dormant, while others perish… Each living creature must be looked upon as a microcosm formed of a host of self-propagating organs inconceivably minute and as numerous as the stars of heaven.' But even if the truth of the theory of Pangenesis be granted, it leaves us as far off as ever from the knowledge of the method by which the first cell or gemmule became endowed with its mysterious properties. Polarity or elective affinity are merely terms that cover our own ignorance. We can but fall back on the old doctrine of a First Cause and a Supreme Will: that life itself sprang in the beginning from the great Life-giver, the great Maker and Sustainer, 'by whom, through whom, and for whom all things were made.'

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THE

EDINBURGH REVIEW,

OR

CRITICAL JOURNAL:

FOR

JULY, 1868.….. OCTOBER, 1868.

TO BE CONTINUED QUARTERLY

JUDEX DAMNATUR CUM NOCENS ABSOLVITUR.

PUBLIUS SYRUS.

VOL. CXXVIII:

LONGMANS, GREEN, READER, AND DYER, LONDON.
ADAM AND CHARLES BLACK,
EDINBURGH.

1868.