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know propagate'ltheir 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. do not believe, as we shall presently see, that;-v 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.
t 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 ‘1) Has the little variability 0f the ass or guinea-fowl, or the small power of endurance of warmth by the reindeer, or of cold by the common camel prevented their domestication ‘2 C1 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 variedJ
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 one or several wild species; The argument mainly relied on by those who believe in the multiple origin 01 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
ago ‘I Since the recent discoveries of flint tools or celts
‘vil‘he doctrine of the origin of our several domestic races
mammal, and France but few distinct from those of
(as I have found with pigeons) extremely uniform, and ww‘t,
everything seems simple enough ; but when these mongrels
are crossed one with another for several generations, qw‘
hardly two of them will be alike; and then the extreme Q
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.
0n 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 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 a 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 oesophagus. 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 :, DOMESTIC PIGEONS 31 aborted! Several other less distinct breeds might be specified.
In the skeletons of the several breeds, the develop
ment 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 vertebrae vary in number; as d0es 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; s0 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 (esophagus; 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 scutellae on the toes, the development of skin between the toes, 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 remarkably. Lastly, in certain breeds, the males and females have come to differ to a slight degree from each other: Ghtogether at least a score of pigeons might be chosen, which, if shown to an ornithologist, and he were told that they were wild birds, would certainly limwked by him as well-defined speciesD Moreover, 1‘ not believe that any ornithologist would place the E p ‘ ' Lcai'i*ier, the short-faced tumbler, the runt, the bafli'gmuter, and fantail in the same genus; more esupe y as in each of these breeds several truly-inherited u (is, or species as he might have called them, could be pm him.
Gigath the differences are between the breeds of pi ons, j, I am fully convinced that the common opinion at turalists is correct, namely, that all have descended the rock—pigeonjfllolumba livia), including under