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Show 188 DOMESTIC PIGEONS. CHAP. VI. gone a co~sidcrable amount of variation, as in the toy-pigeons. vVo shall moreover presently see how eminently favouraLle circumstances have been for a great amount of modification in tho more carcfuUy·tended Lreeds. The reasons for concluding that the several principal races have not descended from so many aboriginal and unlmown stochs may be grouped under the followi.ng six heads :-Firstly, if the eleven chief rooes have not arisen from the variation of some one species, together with its geographical races, they must b descended hom several extremely distinct aboriginal species; for no amount of crossi11g between only six or seven wild forms could produce races so distinct as pouters, carriers, runts, fantail , turbits, short-faced tumLlers, jacobins, and trumpeters. How could crossing produce, for instance, a pouter or a fantail) unless the two supposed aboriginal parents posses. eel the remarkable characters of these breeds? I am aware that some naturalists, following Pallas, believe that crossing gives a strong tendency to variation, independently of the characters inherited from either parent. r:l'hoy believe that it would be easier to raise a pouter or fantail pigeon from crossing two distinct species, neither of which posses eel the characters of these races, than from any single species. I can find few facts in support of this doctrine, and believe in it only to a limited degree; but in a futuro chapter I shall have to recur to this snLject. For our present purpose the point is not material. The question which coneerns us is, whether or not many now and important characters have arisen since man first domesticated the pigeon. On tho ordinary view, variability is due to changed conditions of lifo; on the Pallasian doctrine, variability, or the appearance of new characters, is clue to some mysterious effect from the crossing of two species, neither of which possess the characters in question. In some few instances it is credible, though for several reasons not probable, that well-marked races have been formed by crossing; for instance, a barb might pcrl:aps ha:e been formed by a cross between a long-beaked carqer, havmg large eye-wattles, and some short-beaked pigeon. That many races have been in some degree modified by crossing, ~ncl t?at certain ~arieties which are distinguished only by pecuhar tmts have ansen from crosses between differently-coloured CHAP. VI. THEIR PARENTAGE. 189 varieties, may be admitted as almost certain. On the doctrin\, therefore, that the chief races owe their differences to their descent from distinct species, we must admit that at least eight or nine, or more probably a dozen species, all having the same habit of breeding and roosting on rocks and living in society, either now exist somewhere, or formerly existed but have become extinct as wild birds. Considering how carefully wild pigeons have been collected throughout the world, and what conspicuous birds they are, especially when frequenting rocks, it is extremely improbable that eight or nine species, which were long ago domesticated and therefore must have inhabited some anciently known country, should still exist in the wild state and be unknown to ornithologists. The. hypothesis that such species formerly existed, but have become extinct, is in some slight degree more probable. But the extinction of so many species within the historical period is a bold hypothesis, seeing how little influence man has had in exterminating the common rock-pigeon, which agrees in all its habits of life with the domestic races. The 0. livia now exists ana flourishes on the small northern islands of Faroe, on many islands off the coast of Scotland, on Sardinia and the shores of the Mediterranean, and in the centre of Iuclia. Fanciers have sometimes imagined that the several supposed parent-species 'vore originally confined to small islands, and thus might readily have been exterminated; but the facts just given do not favour the probability of their extinction, even on small islands. Nor is it probable, from what is known of the distribution of birds, that tho islands near Europe should have been inhabited by peculiar species of pigeons; and if we assume that distant oce~tnic islands were the homos of the supposed parent-species, we must remember that ancient voyages were tediously _slow, and that ships were then ill-provided with fresh food,. so that it would not have been easy to bring home living birds. I have said ancient voyages, for nearly all the races of the pigeon wore known before the year 1600, so that the supposed wild .species must have been captured and domesticated before that elate. Secondly.-The doctrine that the chief domestic races have descended from s~veral aboriginal species, implies that several |