182 LUTHER BURBANK 



cal 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 prin- 

 ciples of evolution apply to plants and animals 

 alike, and that much may be learned about the 

 better 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 specific difference. No one nowadays 

 holds that view, with regard to plants at any 

 rate, and the view is probably no more valid in 

 its application to a great number of animals, in- 

 cluding 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- 

 tance. It is beyond question that the human 



