HYBRIDISM 227 



has been crossed with nine other finches, but as not 

 one of these nine species 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. 

 If we were to act thus, and pair brothers and sisters in 

 the case of any pure animal, which from any cause 

 had the least tendency to sterility, the breed would 

 assuredly be lost in a very few generations. 



Although I do not know of any thoroughly well- 

 authenticated cases of perfectly fertile hybrid animals, 

 I have some reason to believe that the hybrids from 

 Cervulus vaginalis and Reevesii, and from Phasianus 

 colchicus with P. torquatus and with P. versicolor are 

 perfectly fertile. There is no doubt that these three 

 pheasants, namely, the common, the true ring-necked, 

 and the Japan, intercross, and are becoming blended to- 

 gether in the woods of several parts of England. 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 (grand- 

 children 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 Captain Hutton, that 



