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Show 222 DOMESTIC PIGEONS. CHAP. VI. and its subsequent divergence, either in the same or more commonly in di~tant countries, into two or more strains, and their gradual com·er ion into sub-breeds, and. these into wellmarked breed..,, are events which would rarely be noticed. The death of a tree, that has attained gigantic dimensions, is recorded; tho low growth of smaller trees and their increase in number excite no attoHtion. In accordance with the belief of the groat power of selection, and of the little direct power of changed conditions oflife, except in causing general variability or plasticity of organisation, it is not surprising that dovecot-pigeons have remained unaltered from time immemorial; and that some toy-pigeons, which differ in little else besides colour from the dovecot-pigeon, have retained the same character for several centuries. For when one of these toy-pigeons had once become beautifully and symmetrically coloured,-when, for instance, a Spot had been produced with the crown of its head, its tail, and tail-coverts of a uniform colour, the rest of the body being snow-whito,-no alteration or improvement would be desired. On tbe other hand, it is not surprising that dnring this same interval of time our hio-hlybred pigeons have undergone an astonishing amount of cha~ge; for in regard to them there is no defined limit to the wi h of the fancier, and there is no known limit to the variabilitv of their characters. What is there to stop the fancier desi~·in()" to give to his carrier a ,longer and longer beak, or to his tnmule~ a shorter and shorter beak? nor has the extreme limit of variability in the beak, if tl1ere be any such limit, as yet been reached. Notwithstanding the great improvement effected within recent times in the short-faced almond tumbler, Mr. Ea~on remarks, "the field is still as open for fresh competitors as It was one .hundred years ago;" but this is perhaps an exagg~ rated assertwn, for tho young of all highly improved fancy b1rds are extremely liable to disease and death. I have heard it objected that the formation of the several domestic races of the pigeon throws no lio·ht on the orio-in of the wild species of the Columhid::e, becauseb their differenc:s are not of the same nature. The domestic races for instance do not differ, or .differ h~rdly at all, in the relative lengths and shapes of the pnmary wmg-featbers, in the relative length of the hind CnAP. VI. MANNER OF FORM"ATION OF TilE CIIIEF RACES. 223 toe, or in habits of life, as in" roosting and building in trees. But the auove objection shows bow completely the principle of selection bas been misunderstood. It is not likely that characters selecied by the caprice of man should resem l>le differences preserved under natural conditions, either from being of direct service to each species, or from standing in correlation with other modified. and serviceable structures. Until man selects birds differing in the relative length of the wing-feathers or toes, &c., no sensible chaRge in these parts should be expected. Nor could man do anything unless these part~ happened to vary under domestication: I do not positively assert that this is the case, although I have seen traces of such variability in the wing-feathers, and certainly in the tail-feathers. It would be a strange fact if the relative length of the hind toe should never vary, seeing how variable the fuot is both in size and in the number of the scutellre. With respect to the domestic races not roosting or building in trees, it is obvious that fanciers would never attend to or select such changes in habits; hut we have seen that the pigeons in Egypt, which do not for some reason like settling on the low mud hovels of the natives, are led, apparently by compulsion, to perch in crowds on the trees. We may even affirm that, if our domestic races had become greatly modified in any of the above specified respects, and it could be shown that fanciers had never attended to such points, or that they did not stand in correlation with other selected characters, the fact, on the principles advocated in this chapter, would have offered a serious difficulty. Let us briefly sum up the last two chapters on the pigeon. We may conclude with confidence that all the domestic races notwithstanding their great amount of difference, are descended from the Columba livia, including under this name certain wild races. But the differences between these latter forms throw no light whatever on the characters which distinguish the domestic races. In each breed or sub-breed the individual birds are more variable than birds in a state of nature; and occasionally they vary in a sudden and strongly-marked manner. This plasticity of organisation apparently results from changed conditions of. life. Disuse has reduced c~rta~n parts of the body. Correlation of growth so ties the orgamsat10n together, that when one part varies other parts |