184 LUTHER BURBANK 



in our day what is doubtless the greatest migra- 

 tion in all history. The races of Europe are 

 flooding into America, and there is a more pro- 

 nounced commingling of racial strains now 

 taking place on our soil than perhaps ever 

 occurred in any one place, or in any single epoch, 

 in the history of the world. 



America owes its present greatness in consid- 

 erable measure to the mingling of moderately 

 divergent strains in the past ; but this fact should 

 not blind us to the menace that lies in the 

 mingling of races that are too divergent to blend 

 advantageously. 



It is this thought that I would put forward as 

 the most important suggestion that arises from 

 the study of the hybridizing experiments which 

 were unsuccessful in blending the hereditary 

 tendencies of certain races of plants that were 

 too widely divergent. 



