THE PHENOMENA OF ORGANIC NATURE. 147 



duce this complete physiological divergence by selective 

 breeding. I stated this very clearly before, and I now 

 refer to the point, because, if it could be proved, not 

 only that this has not been done, but that it cannot be 

 done; if it could be demonstrated that it is impossible 

 to breed selectively, from any stock, a form which shall 

 not breed with another, produced from the same stock ; 

 and if we were shown that this must be the necessary 

 and inevitable result of all experiments, I hold that 

 Mr. Darwin's hypothesis would be utterly shattered. 



But has this been done ? or what is really the state 

 of the case ? It is simply that, so far as we have gone 

 yet with our breeding, we have not produced from a 

 common stock two breeds which are not more or less 

 fertile with one another. 



I do not know that there is a single fact which would 

 justify any one in saying that any degree of sterility has 

 been observed between breeds absolutely known to have 

 been produced by selective breeding from a common 

 stock. On the other hand, I do not know that there 

 is a single fact which can justify any one in asserting 

 that such sterility cannot be produced by proper 

 experimentation. For my own part, I see every reason 

 to believe that it may, and will be so produced. For, 

 as Mr. Darwin has very properly urged, when we 

 consider the phenomena of sterility, we find they are 

 most capricious ; we do not know what it is that 

 the sterility depends on. There are some animals 

 which will not breed in captivity; whether it arises 

 from the simple fact of their being shut up and 

 deprived of their liberty, or not, we do not know, but 

 they certainly will not breed. What an astounding 



