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Show 218 DOMESTIC PIGEONS. CHAP. VI. difTcrcd slightly in several chamctors from those kept by a~othcr. I po scssc<l ·orne excellent barbs descended from a pau which had won a prize, and another lot descended from a stock formerly kept by that famous fancier Sir John Scbri?'ht, and the e plainly differed in the form of the beak; but the differences were so slight, tha£ they could hardly bed scribed by words. AO'ain the common EnO'lish and Dutch tumbler differ in a b ' b somewhat greater degree, both in length of beak and shape of head. What first caused these slight differences cannot be explained any more than why one roan has a long nose and another a short one. In the strains long kept distinct by different fanciers, such differences are so common that they cannot be accounted for by the accident of the birds first chosen for breeding having been originally as diiTerent as they now arc. The explanation no doubt lies in selection of a slightly different nature having been applied in each case; for no two fanciers have exactly the same taste, and consequently no two, in choosing and carefully matching their birds, prefer or select exactly the same. As each roan naturally admires his own birds, he goes on continually exaggerating by selection whatever slight . peculiarities they may pos css. This will more especially happen with fanciers living in different countries, who do not compare their stocks and aim at a common standard of perfection. Thus, when a mere strain has once been formed, unconscious selection steadily tends to augment the amount of difference, and thus converts the strain into a sub-breed, and this ultimately into a well-marked breed or race. The principle of correlation of growth should never be lost sight of. l\1o t pig ons have small feet, apparently caused by their lessened usc, and from correlation, as it would appear, their beaks have likewise become reduced in length. The beak is a conspicuous organ, and, as soon as it had thus become perceptibly shortened, fanciers would almost certainly strive to reduce it still more by the continued selection of birds with the shortest beaks; whilst at the same time other fanciers, as we know has actually been the case, would, in other subbreeds, strive to increase its length. With the increased length of the beak, the tongue would become greatly lengthened, as would the eyelids with the increased development CHAP. VI. MANNER OF FORMATION OF TilE CIIIEF RACES. 219 of the eye-wattles; with the reduced or increased size of the feet the number of the scutcllro would vary ; with the length of the winO' the number of the primary wing-feathers would diiTcr; :nd with the increased length of the body in the pouter the number of the sacral vcrtcbrre \Yould be augmented. These important and correlated differences of structure do not invariably characterise any breed; but if they had been attended to and selected with as much. care as the more conspicuous external differences, there can hardly be a doubt that they would have been rendere<l constant. Fanciers could assuredly have ma<le a race of tumblers with nine instead of ten primary wing-feathers, seeing how often the number nine appears without any wish on their part, and indeed in the case of the white-winged varieties in opposition to their wish. In a similar manner, if the vertebn.e had been visible and had been attended to by fanciers, assmedly an additional number might easily have boon fixed in the poute1·. If these · latter characters had once been rendered constant we should never have suspected that they had at first been highly variable, or that they had arisen from correlation, in the one case with the shortness of the wings, and in the other case with the length of the body. In order to understand how the chief domestic mces have become distinctly separated from each other, it is important to bear in mind, that fanciers constantly try to breed from the best birds, and consequently that those which are inferior in the requisite qualities are in each generation neglected; so that after a time th~ less improved parent-stocks anJ many subsequently formed intermediate grades become extinct. This . has occurred in the case of the pouter, turbit, and trumpeter, for these hjghly improved breeds are now left without any links closely connecting them either with each other or wjth the aborjginal rock-pigeon. In other countries, indeed, where the same care has not been applied, or where the same fashjon has not prevailed, the earlier forms may long remain unaltered or altered only in a slight degree, and we are thus sometimes enabled to recover the connectjng links. This is the case in Persia and India wjth the tumbler and carrier, which there differ but slightly from the rock-pigeon in the pro- |