?4-0 



Hybridism. Chap. ix. 



experiments have been fairly tried: for instance, the canary-bird 

 hasbeen crossed with nine distinct species of finches, but, as not 

 one of these breeds freely in confinement, we have no right to 

 expect that the first crosses between them and the canary, 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 increasing. 



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 Eeevesii, 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 Chinese 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 (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 lor 

 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 first produced perfectly 

 fertile hybrids, or that the hybrids subsequently reared under 

 domestication became quite fertile. This latter alternative, which 



