178 THE SURVIVAL OF THE UNLIKE. [vi. 



which man has done the most to modify and improve, 

 natural forces have been guiding the human ingenuity, 

 and the operator has fallen unconsciously into the very 

 methods which nature had chosen for the same condi- 

 tions. We pride ourselves upon the increasing number 

 of varieties of fruits of American origin, and we have 

 noticed how they differ from their foreign parents; but 

 we have not thought that it is the American environ- 

 ments which have been at the bottom of the evolution. 

 Man's greatest power, I had almost said his only one, is 

 selection. He may choose the plant which suits him and 

 propagate it. This has been going on half unconsciously 

 for centuries, and this gradual evolution is no doubt the 

 cause of the permanence of many of the types or races 

 of cultivated plants. Intelligent selection, having in 

 mind an ideal form, is man's nearest approach to the 

 Creator in his dealings with the organic world. This 

 has been the greatest force in the wonderful upbuilding 

 of our cultivated flora. "The key," says Darwin, "is 

 man's power of accumulative selection: nature gives 

 successive variations ; man adds them up in certain 

 directions useful to him." 



There is dispute among scientific men as to the 

 adequacy of natural selection — which is the means so 

 successfully imitated by man — as a method of evolution 

 of the organic world. There are, no doubt, other forces 

 at work, and none of the forces operate equally in all 

 groups of organisms. For plants, I am convinced that 

 natural selection is the chief agent of progression or 

 evolution, once the initial differences given, and for 

 the same reasons I consider human selection to be the 

 one great force in the improvement of cultivated plants. 

 All theories of evolution seem to teach us that thfi final 



