SOME INTERESTING FAILURES 



had led to seemingly more practical results. For 

 they serve to emphasize a great fundamental 

 truth of heredity, which has a more important 

 bearing on the problems of racial development 

 of all organic beings, including man himself. It 

 has become more and more clear in recent years 

 that the underlying principles of evolution apply 

 in large measure to plants and animals alike, 

 and that much may be learned about the proper 

 breeding of mankind from a direct study of the 

 breeding of the lower organisms. 



And as regards the particular case under con- 

 sideration, it is scarcely to be doubted that we 

 may draw important lessons from the obvious 

 results of the hybridizing of plants to apply to 

 the commingling of human races. 



It is commonly held that the various existing 

 races of man constitute a single species. But this 

 classification was made under the influence of the 

 old idea that sterility of offspring is a valid test 

 of speciJBc difference. No one nowadays holds 

 that view, with regard to plants at any rate, and 

 the view is probably no more valid in its appli- 

 cation to a great number of animals, including 

 man himself. 



But, in any event, the question as to whether 

 mankind constitutes a single species or several 

 species is a matter of definition of no real impor- 



[301] 



