1 86 THE EVOLUTIONIST AT LARGE. 



points. But besides being able to modify the 

 visible and outer structure of the animal, we 

 arc also able to modify, by indirect indica- 

 tions, the hidden and inner structure of the 

 brain. We choose the best ratter among our 

 terriers, the best pointer, retriever, or setter 

 among other breeds, to become the parents 

 of our future stock. We thus half uncon- 

 sciously select particular types of nervous 

 system in preference to others. Once upon 

 a time we used even to rear a race of dogs 

 with a strange instinct for turning the spit in 

 our kitchens ; and to this clay the Cubans 

 rear blood-hounds with a natural taste for 

 hunting down the trail of runaway negroes. 

 Now, everybody knows that you cannot teach 

 one sort of dog the kind of tricks which come 

 by instinct to a different sort. No amount 

 of instruction will induce a well-bred terrier 

 to retrieve your handkerchief : he insists upon 

 worrying it instead. So no amount of instruc- 

 tion will induce a well-bred retriever to worry 

 a rat : he brings it gingerly to your feet, as if it 



