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Show 96 ON CROSSING AS A CAUSE CHAP. XV. Hampshire sheep and Southdowns; and the long-woolled Cotswold were improved by crosses with the Leicester, which latter aO"ain is believed to have been a cross between several 0 • long-woolled sheep. Mr. Spooner, after considering the varwus cases which have been carefully recorded, concludes "that from a. judicious pairing of cross-bred animals it is practir_able to establish a new breed." On the Continent the history of several crossed races of cattle and of other animals has been well ascertained. To give one instance: the King of vVurtemberg, after twenty-five years' careful breeding, that is after six or seven generations, made a new breed of cattle from a cross between a Dutch and Swiss breed, combined with other breeds. 24 The Sebright bantam, which breeds as true as any other kind of fowl, was formed about sixty years ago by a complicated cross. 25 Dark Brahmas, which are believed by some fanciers to constitute a distinct species, were undoubtedly formed 26 in the United States, "vithin a recent period, by a cross between Chittagongs and Cochins. With plants I believe there is little doubt that some kinds of turnips, now extensively cultivated, are crossed races ; and the history of a variety of wheat which was raised from two very distinct varieties, and which after six years' culture presented an even sample, has been recorded on good authority.27 Until quite lately, cautious and experienced breeders, though not averse to a single infusion of foreign blood, were almost universally convinced that the attempt to establish a new race, intermediate between two widely distinct races, was hopeless: " they clung with superstitious tenacity to the doctrine of purity "of blood, believing it to be the ark in which alone true safety " could be found." 28 Nor was this conviction unreasonable : when two distinct races are crossed, the offspring of the first generation are generally nearly uniform in character; but even this sometimes fails to be the case, especially with crossed dogs and fowls, the young of which from the first are sometimes much 24 'Bulletin de la Soc. d'Acclimat.,' 1862, tom. ix. p. 463. See also, for other cases, M1\'L Moll and Gayot, 'Du Brnuf,' 1860, p. x.uii. 25 'Poultry Chronicle,' vol. ii., 1854, p. 36. 26 'The Poultry Book,' by W. B. Tegetmeicr, 1866, p. 58. ~7 'Gardener's Chronicle, 1852, p. 765. 28 Spooner, in 'Journal Royal Agri-cult. Soc.,' vol. xx., part ii. CruP. XV. OF THE MODIFICATION OF RACES. 97 diversif.i ed. A s cross-b red animals are generally of large s1ze ~nd VI?orous, they have been raised in great numbers for Immediate consumption. But for breeding they are found to be utterly useless; for though they may be themselves uniform in charactAr wl · d • J ' 1en paue together they yield during many gene-ratwns o~spring astonishingly diversified. The breeder is driven to d.espair, and concludes that he will never form an intermedJate :·ace. But from the cases already given, and from others whwh have been recorded, it appears that patience alone is necessary ·, as Mr · Spoon ei . remar· 1,-.s, " nature opposes no barrier to succe~sful admixture ; in the course of time, by the aid of selectwn and careful weeding, it is practicable to establish a new ?re~d." After six or seven generations the hoped-for r~sult will m. most cases be obtained; but even then an occasiOnal reversiOn, or f~ilure to keep true, may be expected. rrhe attemp~, however, w1ll assuredly fail if the conditions of life be decidedly unfavourable to the characters of either parentbreed. 29 . Although :he grandchildren and succeeding generations of cross-bre~ ammals are generally variable in an extreme degree, so.me curwus exceptions to the rule have been observed, both With crosse~ races and species. Thus Boitard and C01·bie 3o ashs'e rt that from a Pouter and a Runt " a 0 ava1 1. er w1. 11 appear w. JCh :ve hav~ classe~ ~mongst pigeons of pul'e mce, beeause i~ transmits all Its quahties to its posterity." The editor ,. th 'Po lt Cl · 1 '3 b 01 u. ry u·omc e I red some bluish fowls from a blacke Spamsh"cock an~ a Malay hen; and these remained true to cof loul' . · genemtwn. after g·eneration ·" The H.1 ma1 a yan b Teed o ra?blts was certamly formed by crossing two sub-varieties of the sil ver-gre! rabbit; although it suddenly assumed its present character, wluch differs much from that of either parent-b d t .t h . ree ' ye 1 as ever smce been easily and truly propagated. I crossed so.me Labra~or and Penguin ducks, and recrossed the mongrels WI~h Pengm~s ; afterwards, most of the ducks reared during tl~ree generatwns were nearly uniform in character, being brown W!th a white crescentic mark on the lower part of the breast, 29 See. Colin's 'Traite de Phys. Comp. des Ammaux Domestiques,' tom. ii. p. 536• where this subject is well treated. VO.L. II. 30 'Les Pigeons,' p. 37. 31 Vol. i.., 1854, p. 101. H |