« PreviousContinue »
know propagate their kind so truly, were the offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many very closely allied natural species—for instance, of the many foxes—inhabiting different quarters of the world. I do not believe, as we shall presently see, that the whole amount of difference between the several breeds of the dog has been produced under domestication; I believe that some small part of the difference is due to their having descended from distinct species.] In the case of some other domesticated species, there is presumptive, or even strong evidence, that all the breeds have descended from a single wild stock. It has often been assumed that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates. I do not dispute that these capacities have added largely to the value of most of our domesticated productions; but how could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations, and whether it would endure other climates ? Has the little variability of the or guinea-fowl, or the small power of endurance of warmth by the reindeer, or of cold by the common camel prevented their domestication ? I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would vary on an average as largely as the parent species of our existing domesticated productions have varied.)
In the case of most of our anciently. domesticated animals and plants, it is not possible to come to any definite conclusion, whether they have descended from
several wild species. The argument mainly relied on by those who believe in the multiple origin of our domestic animals is, that we find in the most ancient records, more especially on the monuments of Egypt, much diversity in the breeds; and that some of the breeds closely resemble, perhaps are identical with, those still existing. Even if this latter fact were found more strictly and generally true than seems to me to be the case, what does it show, but that some of our breeds originated there, four or five thousand years
Since the recent discoveries of flint tools or celts in the superficial deposits of France and England, few geologists will doubt that man, in a sufficiently civilized state to have manufactured weapons, existed at period extremely remote as measured by years; and we know that at the present day there is hardly a tribe so barbarous as not to have domesticated at least the dog.
The origin of most of our domestic animals will probably for ever remain vague. But I may here state, that looking to the domestic dogs of the whole world, I have, after a laborious collection of all known facts, come to the conclusion that several wild species of Canidæ have been tamed, and that their blood, more or less mingled, flows in the veins of our many domestic breeds. In regard to sheep and goats I can form no opinion. From facts communicated to me by Mr. Blyth, on the habits, voice, and const ion, &c., of the humped Indian cattle, it is probable that these descended from a different aboriginal stock from our European cattle ; and several competent judges believe that these latter have had more than one wild parent. With respect to horses, from reasons which I cannot here give, I am with much doubt inclined to believe, in opposition to several authors, that all the races have descended from one wild stock. Mr. Blyth, whose opinion, from his large and varied stores of knowledge, I should value more than that of almost any one, thinks that all the breeds of poultry have proceeded from the common wild Indian fowl (Gallus bankiva). In regard to ducks and rabbits, the breeds of which differ considerably from each other in structure, the evidence preponderates in favour of their having all descended from the common wild duck and rabbit.
The doctrine of the origin of our several domestic races from several aboriginal stocks, has been carried to an absurd extreme by some authors.) They believe that every race which breeds true, let the distinctive characters be ever so slight, has had its wild prototype. [At this rate there must have existed at least a score of species of wild cattle, as many sheep, and several goats in Europe alone, and several even within Great Britain. One author believes that there formerly existed in Great Britain eleven wild species of sheep peculiar to it! When we bear in mind that Britain has now hardly one peculiar
mammal, and France but few distinct from those of Germany and conversely, and so with Hungary, Spain, &c., but that each of these kingdoms possesses several peculiar breeds of cattle, sheep, &c., we must admit that many domestic breeds have originated in Europe ; for whence could they have been derived, as these several countries do not possess a number of peculiar species as distinct parent-stocks ? So it is in India. Even in the case of the domestic dogs of the whole world, which I admit to have descended from several wild species, it cannot be doubted that there has been an immense amount of inherited variation ; for who will believe that animals closely resembling the Italian greyhound, the bloodhound, the bull-dog, pug-dog, or Blenheim spaniel, &c.—so unlike all wild Canidæ-ever existed freely in a state of nature ? (It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species; but by crossing we can only get forms in some degree intermediate between their parents; and if we account for our several domestic races by this process, we must admit the former existence of the most extreme forms, as the Italian greyhound, bloodhound, bull-dog, &c., in the wild state. Moreover, the possibility of making distinct races by crossing has been greatly exaggerated. Many cases on record, showing that a race may be modified by occasional crosses, if aided by the careful selection of those individual mongrels which present any desired character ; but that a race could be obtained nearly intermediate between two extremely different races or species, I can hardly believe. Sir J. Sebright expressly experimented for this object, and failed. The offspring from the first cross between two pure breeds is tolerably and sometimes (as I have found with pigeons) extremely uniform, and und everything seems simple enough ; but when these mongrels are crossed one with another for several generations, avent hardly two of them will be alike; and then the extreme J difficulty, or rather utter hopelessness, of the task becomes apparent. Certainly, a breed intermediate between two very distinct breeds could not be got without extreme care and long-continued selection ; nor can I find a single case on record of a permanent race having been thus formed.
On the Breeds of the Domestic Pigeon.-Believing that it is always best to study some special group, I have,
after deliberation, taken up domestic pigeons. I have kept every breed which I could purchase or obtain, and have been most kindly favoured with skins from several quarters of the world, more especially by the Hon. W. Elliot from India, and by the Hon. C. Murray from Persia. Many treatises in different languages have been published on pigeons, and some of them are very important, as being of considerable antiquity. I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs. The diversity of the breeds is something astonishing. Compare the English
the English carrier and the short-faced tumbler, and see the wonderful difference in their beaks, entailing corresponding differences in their skulls. The carrier, more especially the male bird, is also remarkable from the wonderful development of the carunculated skin about the head; and this is accompanied by greatly elongated eyelids, very large external orifices to the nostrils, and a wide gape of mouth. The short-faced tumbler has a beak in outline almost like that of finch; and the common tumbler has the singular inherited habit of flying at a great height in a compact flock, and tumbling in the air head over heels. The runt is a bird of great size, with long, massive beak and large feet; some of the sub-breeds of runts have very long necks, others very long wings and tails, others singularly short tails. The barb is allied to the carrier, but, instead of a very long beak, has a very short and very broad one. The pouter has a much elongated body, wings, and legs ; and its enormously developed crop, which it glories in inflating, may well excite astonishment and even laughter. The turbit has a very short and conical beak, with a line of reversed feathers down the breast; and it has the habit of continually expanding slightly the upper part of the æsophagus. The Jacobin has the feathers so much reversed along the back of the neck that they form a hood; and it has, proportionately to its size, much elongated wing and tail feathers. The trumpeter and laugher, as their names express, utter a very different coo from the other breeds. The fantail has thirty or even forty tail-feathers, instead of twelve or fourteen—the normal number in all members of the great pigeon family; and these feathers are kept expanded, and are carried so erect, that in good : birds the head and tail touch : the oil-gland is quite
aborted. Several other less distinct breeds might be specified.
In the skeletons of the several breeds, the development of the bones of the face in length and breadth and curvature differs enormously. The shape, as well as the breadth and length of the ramus of the lower jaw, varies in a highly remarkable manner. The caudal and sacral vertebræ vary in number ; as does the number of the ribs, together with their relative breadth and the presence of processes. The size and shape of the apertures in the sternum are highly variable; so is the degree of divergence and relative size of the two arms of the furcula. The proportional width of the gape of mouth, the proportional length of the eyelids, of the orifice of the nostrils, of the tongue (not always in strict correlation with the length of beak), the size of the crop and of the upper part of the æsophagus; the development and abortion of the oil-gland ; the number of the primary wing and caudal feathers; the relative length of wing and tail to each other and to the body; the relative length of leg and of the feet; the number of scutellæ on the toes, the development of skin between the tocs, are all points of structure which are variable. The period at which the perfect plumage is acquired varies, as does the state of the down with which the nestling birds are clothed when hatched. The shape and size of the eggs vary. The manner of flight, and in some breeds the voice and disposition, differ markably. Lastly, in certain breeds, the males and females have come to differ to a slight degree from each other. Altogether at least score of pigeons might be chosen, which, if shown to an ornithologist, and he were told that they were wild birds, would certainly boquanked by him as well-defined species. Moreover, I do not believe that any ornithologist would place the Este carrier, the short-faced tumbler, the runt, the barb, upouter, and fantail in the same genus ; more especially, as in each of these breeds several truly-inherited sube Freds, or species as he might have called them, could be wn him.
Grant as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under