HYBRIDISM 15 



respect to the fertility in successive generations of the 

 more fertile hybrid animals, I hardly know of an in- 

 stance in which two families of the same hybrid have 

 been raised at the same time from difiEerent parents, so 

 as to avoid the ill effects of close interbreeding. On the 

 contrary, brothers and sisters have usually been crossed 

 in each successive generation, in opposition to the con- 

 stantly repeated admonition of every breeder. And in 

 this case, it is not at all surprising that the inhereni. 

 sterility in the hybrids should have gone on increas- 

 ing. 



Although I know of hardly any thoroughly well- 

 authenticated cases of perfectly fertile hybrid animals, I 

 have reason to believe that the hybrids from Cervulus 

 vaginalis and Reevesii, and from Phasianus colchicus 

 with P. torquatus, are perfectly fertile. M. Quatrefages 

 states that the hybrids from two moths (Bombyx cynthia 

 and arrindia) were proved in Paris to be fertile inter se 

 for eight generations. It has lately been asserted that 

 two such distinct species as the hare and rabbit, when 

 they can be got to breed together, produce offspring 

 which are highly fertile when crossed with one of the 

 parent-species. The hybrids from the common and Chi- 

 nese geese (A. cygnoides), species which are so different 

 that they are generally ranked in distinct genera, have 

 often bred in this country with either pure parent, and 

 in one single instance they have bred inter se. This was 

 effected by Mr. Eyton, who raised two hybrids from the 

 same parents, but from different hatches; and from these 

 two birds he raised no less than eight hybrids (grand- 

 children of the pure geese) from one nest. In India, 

 '^l however, these cross-bred geese must be far more fertile; 



— Science — 18 



