234 EVOLUTION IN NATURE AND UNDER DOMESTICATION. 



originate from a cross between two species of rats, we may ex- 

 pect very striking new characters to result from a cross 

 between two wild species of Gallus. If, therefore, the hybrids 

 between tame-chickens and a species of wild-chicken, other 

 than Bankiva, are fertile when crossed back into the tame 

 stock, this fact is sufficient to account for the remarkable varia- 

 bility in the domestic fowl. Darwin adduces an instance of a 

 hybrid G. Sonnerati-bankiva which was not completely sterile. 

 We know now that partial sterility is no bar to reproduction, 

 and eventual full fertility of the descendants. This is clearly 

 shown by the experiments of Sellings with Lyon beans, and of 

 Detleffsen with guinea-pigs. 



During our stay on Java we observed numerous hybrids 

 between Gallus varius and tame fowls. These hybrids are pro- 

 duced in regions where the natives make a speciality of them. 

 On some of the islands Karimon Djawa, laying off the North 

 coast of Java, such hybrids are produced in great numbers. 

 They are commonly produced by pegging a tame hen down on 

 the ground near a bottomless basket under which a tame Vari- 

 us male is kept. A tame Varius hen is introduced under the 

 cage, and when the male mounts this hen to copulate, it is 

 withdrawn and the cage with the male pushed over the tame 

 hen. 



The hybrids are called "Bekisar" and they are very highly 

 prized both by the natives and by Chinese and Arabs. They are 

 commonly kept in bamboo cages slung high in the air on bam- 

 boo poles, where they waken early and crow. Very high prices 

 are sometimes paid for individual birds with particularly at- 

 tractive voices. These Bekisars are by no means sterile. In 

 Pasoeroean, where a great number of Bekisars are kept by 

 Chinese, we saw several very beautilul cocks in cages, bred 

 from Bekisar fathers. We remember a white male with a long 

 bluish tail and a blue-bronze neck, of which every feather was 

 rounded as in Varius and bordered with black, and an enorm- 

 ous black cock kept by a Chinese carpenter, that had the 

 blue comb and median wattle of Varius. 



