The Making of Species 



Bird fanciers when crossing the canary with 

 wild species of finch, almost invariably use a hen 

 canary as the female parent, because domesticated 

 female animals breed more readily than do captive 

 wild ones. 



The domestic yak breeds frequently in the 

 Himalayas with the perfectly distinct zebu or 

 humped cow of India, and the hybrids are fertile. 

 Yet the zebu and the Indian buffalo, living con- 

 stantly side by side in the plains of India, never 

 interbreed at all. 



Among wild ruminants of this hollow-horned 

 family, the Himalayan Argali (Ovis ammon) ram, 

 a giant sheep of the size of a donkey, has been 

 known to appropriate a herd of ewes of the Urial 

 (O. vignei\ a very distinct species of the size of 

 a domestic sheep. Many hybrids were born, and 

 these, in turn, bred with the pure urials of the 

 herd. 



In our parks the little Sika deer of Japan 

 (Cervus sika], a species about the size of the 

 fallow-deer, with an even more marked seasonal 

 change of colouration and antlers having only 

 three tines, breeds with the red deer, and the 

 hybrids are fertile. 



In certain parts of Asia Minor the natives 

 cross the female one-humped camel with the male 

 of the bactrian or two-humped species. The 

 hybrids (which are one-humped) will breed with 

 the pure species ; but, although the hybrids are 



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