GROWTH AND REPRODUCTION 63 



British Association. He says: "The great engine 

 of natural selection is taunted nowadays, as it was 

 fifty years ago, with being merely a negative power. 

 I venture to think that the mnemic hypothesis of 

 evolution makes the positive value of natural selec- 

 tion more obvious. If evolution is a process of drill- 

 ing organisms into habits, the elimination of those 

 that cannot learn is an 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 perform- 

 ing dogs accommodating themselves to conditions 

 of increasing complexity, 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 something new. Natural selection 

 attains in a blind 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." 



