304 ORIGIN OF SPECIES 



or that their hybrids, should be perfectly fertile. Again, with 

 respect to the fertility in successive generations of the more 

 fertile hybrid animals, I hardly know of an instance in which 

 two families of the same hybrid have been raised at the same 

 time from different 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 constantly repeated admonition of every 

 breeder. And in this case, it is not. at all surprising that the 

 inherent sterility in the hybrids should have gone on in- 

 creasing. 



Although I know of hardly any thoroughly well-authen- 

 ticated cases of perfectly fertile hybrid animals, I have reason 

 to believe that the hybrids from Cervulus vaginalis and Ree- 

 vesii, 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 ofif- 

 spring, 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 in- 

 stance 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 (grandchildren of the pure geese) 

 from one nest. In India, however, these cross-bred geese 

 must be far more fertile ; for I am assured by two eminently 

 capable judges, namely Mr. Blyth and Capt. Hutton, that 

 whole flocks of these crossed geese are kept in various parts 

 of the country ; and as they are kept for profit, where neither 

 pure parent-species exists, they must certainly be highly or 

 perfectly fertile. 



With our domesticated animals, the various races when 

 crossed together are quite fertile ; yet in many cases they are 

 descended from two or more wild species. From this fact we 

 must conclude either that the aboriginal parent-species at 



