president's address. 27 



integral part of the process, and is no less real because it is carried out 

 by a self-acting system. It is surely a positive gain to the harmony of 

 the universe that the discordant strings should break. But natural 

 selection does more than this ; and just as a trainer insists on his per- 

 forming dogs accommodating themselves to conditions of increasing com- 

 plexity, so does natural selection pass on its pupils from one set of 

 conditions to other and more elaborate tests, insisting that they shall 

 endlessly repeat what they have learned and forcing them to learn some- 

 thing new. Natural selection attains in a blind, mechanical way the ends 

 gained by a human breeder ; and by an extension of the same metaphor 

 it may be said to have the power of a trainer — of an automatic master 

 with endless patience and all time at his disposal. 



