The question next arises, whether the dog is a domesticated form of any other species of the genus Canis, e. g. the wolf; the fox, or the jackal ; or whether it is descended from an original wild stock, which has sub sequently become extinct. Now the fox may be at once excluded, as differing in the vertical elongation of the pupil, the peculiar bushiness of the tail, and in other charac ters. The affinity of the dog to the jackal is certainly not so close as that which it bears to the wolf; and there are many dis tinguished naturalists who regard the latter as its original. In support of this view, the following considerations may be urged. No specific character has yet been framed so as to be equally applicable to all the breeds of dogs, which does not include the wolf also ; and it does not seem likely that any valid specific distinction can be established upon anatomical grounds only. The various races of wild dogs, in proportion to their entire emancipa tion from the influence of man, exhibit more and more of the lank and gaunt form, the lengthened limbs, the long and slender muzzle, and the great comparative strength, which cha racterise the wolf ; and in the dingo of Aus tralia, which presents these peculiarities in the most marked degree, and which may be con sidered as the most remote from a state of do mestication, the tail assumes the slightly bushy form of that of the wolf. In no point of its osteology does the wolf differ more from dogs in general, than they differ from each other; and the interval, in fact, is much less between the wolf and the races of dogs just alluded to, than it is between these and the races which most strongly exhibit the influ ence of domestication. Further, the wolf and the dog readily breed together, and their progeny is fertile with either of the parent races ; but whether the hybrids thus produced are fertile with each other, and a new race can be thus established, has not yet been ascertained. The term of utero-gestation is the same for the wolf as for the dog, viz. sixty-three days ; that of the jackal, on the other hand, is but fifty-nine. It is a remark able fact, that the habit of barking is pe culiar to dogs which have been accustomed to intimate association with Man ; and, like variety of colour, it is soon induced in the progeny of those to whom it is not natural, when these are reared in a state of domes tication. Thus, the puppies of the Esqni maux dogs brought home by our Arctic ex plorers, being accustomed to the sound of the human voice from the earliest period, learn to bark, whilst their parents remain confined to their original sounds.
The principal objection to the idea of the specific identity of the two races, lies in their difference of psychical character; the wolf being apparently altogether destitute of that disposition to attach itself to man, and of that capacity of modification under his in fluence, which is so marked a feature in the nature of the dog. It has been asserted that the wolf is so untameably savage, that it would require ages of domestication to render it even moderately tractable, if, indeed it could ever be brought under subjection. Such an assertion, however, does not seem borne out by facts. Mr. T. Bell* relates an instance of friendly recognition towards him self and other persons, shown by a bitch wolf at the Zoological Gardens ; and cites from Mr. Fred. Cuvier a very remarkable instance of affectionate and submissive attachment shown by a young wolf towards the individual by whom he had been brought up, in a degree that scarcely seems inferior to that manifested by the dog. " Now, if we find," he remarks, " that the mere education of a young wolf, taken from its parents in a wild state, could so far change its natural disposition, and render it so fond, so intelligent, and so grate ful as this, what may we not expect from the successive transmission of improvement by the culture and training of a whole race for ages ?" On the other hand, in those races of dogs which have become emancipated from human control, the psychical nature of the wolf developes itself, in precise proportion to the approach presented to its physical charac ters. And even in the most domesticated breeds, instances of spontaneous reversion to wild habits are occasionally to he met with. " Thus," says Mr. Blyth, " I have known this to occur in a male.pointer and a female grey
hound; the latter was so fine a specimen of the breed, that on being entrapped, it was thought desirable to obtain a litter from her, which was accordingly effected ; but while her puppies were very young, she managed to escape to the woods, and never returned ; three of her progeny grew to be excellent hounds, but two others proved quite irreclaim able, and escaping from servitude, like their dam, were finally shot, for their destructive poaching propensities."* Thus it appears that, even if we hesitate in pronouncing in favour of the specific identity of the dog and the wolf, there is, at any rate, no valid ground for the establishment of a specific distinction between them ; and if it should prove that the hybrid offspring are fer tile amongst themselves, and that a vigorous mixed race is the result, the probability of their specific identity would be greatly in creased. The required proof, however, could only be afforded by the actual production from the wolf stock, of a race having the aptitude for domestication, and capacity for variation, exhibited by the dog.
There is another mode of looking at the question, however, which has been recently suggested by Professor Agassiz.t This distin guished naturalist thinks it impossible to ac count for the geographical distribution and va rieties of conformation of many existing species of animals, without having recourse to the idea that, instead of all the individuals of that spe cies having descended from a single parentage, or pair of • protoplasts,' they are the offspring of several distinct pairs of protoplasts,' first introduced in different localities, all possessing the same essential nature, but having that nature modified in accordance with the spe cial conditions in which each was destined to exist. From the definition of species, there fore, he would exclude the idea of identity of descent, and would substitute that of8inzikrity; but would still base his distinction of species, as do other naturalists, on the constant trans mission of some well-marked peculiarity com mon to all the races, and would thus as sociate all those which obviously partake of a common nature, and are disposed to free intermixture, notwithstanding the non-iden tity of their parentage.* He would probably accord with other naturalists, therefore, in regarding the different breeds of dogs as va rieties of one species ; but would attribute the origin of their several peculiarities in part to the differences in their first parents, which were not, however, sufficient to constitute specific distinctions. Although there may be cases in which such an hypothesis presents the readiest solution of the difficulty, yet it can scarcely be accepted as applicable to that of the dog ; for we do not here find that the races which most nearly approximate to the wild state in different parts of the world, do present any differences that enable us to re gard them as the respective ancestors of our most diverse domesticated breeds. If, for example, it could be shown that the Esqui maux dog peculiarly resembled the mastiff, that the Indian dhole might be regarded as the progenitor of the greyhound, that the Australian dingo was the probable ancestor of the spaniel, and that the American wild-dog gives us the type of the pug, the hypothesis of Professor Agassiz might be admitted to possess a considerable claim to our reception. But so far is this from being the case, that, as already pointed out, the several races of wild dogs present a remarkable conformity to a common type; and neither of them can be looked to, in preference to the others, as the probable source of those domesticated breeds which are most diverse from each other, and from the supposed common type. Moreover, there is a strong probability, considering the very remarkable character of the zoology of New Holland, that the dingo was not indige nous to that country, but that it was intro duced there by its human colonizers ; thus, being a descendant of the Indian dole, or of the same stock with it. Hence, even if we admit the multiplication of ' protoplasts' in the case of the dog, we are still driven back upon the influences of domestication as the direct or indirect source of those variations from the fundamental type, by which the existing races are severally characterised.