76 A NEW THEORY OF EVOLUTION. 



is of pure or nearly pure blood, the stock 

 will not be permanent. 



A herd of hybrids, for example, cannot, 

 within themselves, perpetuate a stock inter- 

 mediate between the two pure races from 

 which they came. 



The proposed test is quite practicable in 

 the case of domestic animals, and with 

 them its value may be ascertained in a few 

 years. 



We do not know that experiments of the 

 kind suggested have been made purposely, 

 but our propositions are based on the uni- 

 form experience of breeders. 



Cross-breeding of domestic animals has 

 been diligently pursued during the last 

 century, and yet there has not been pro- 

 duced a permanent stock intermediate be- 

 tween two pure breeds. Every cross-bred 

 stock has died out, unless bred into a pure 

 race, by continuous mating with pure blood. 



Several breeds of cattle are very closely 

 allied to each other, and a new breed in- 

 termediate between some of them would 

 certainly have been produced if Nature did 

 not prohibit persistent intermediaries. The 

 profit that would arise from an inter- 

 mediate breed of cattle, that combined the 

 excellences of two races e.g., high capacity 



