The Making of Species 



types, such as happens when colour-forms are 

 crossed. 



M. Suchetet bred hybrid gold = Amherst 

 pheasants for four generations, and they retained 

 the hybrid character. The young bred by 

 Darwin from a pair of common = Chinese geese 

 hybrids " resembled," he says, " in every detail 

 their hybrid parents." 



When hybrids have been as has far more 

 usually been the case bred back to one 

 of the pure stocks, the hybrid characters have 

 shown, as might be expected, a tendency quickly 

 to disappear. The three-quarter-bred polar bear 

 now in the London Zoological Gardens is a 

 pure polar save for a brown tinge on the back. 

 A three-quarter Amherst = gold pheasant in the 

 British Museum is a pure Amherst save for the 

 larger crest, and a patch of red on the abdomen. 

 When three-quarter-bred pintail = common duck 

 hybrids were bred back to the pintail, the off- 

 spring "lost all resemblance to the common 

 duck." In the case of the Argali-urial herd of 

 wild sheep above-mentioned, after the usurping 

 Argali ram had been killed by wolves, the hybrids 

 bred with the urials, with the result that the herd 

 renewed the appearance of pure urial. 



Thus, except in the very improbable case of a 

 family of hybrids going off and starting a colony 

 by themselves, the effect of hybridism on the 

 evolution of species seems likely to have been 



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