Permanence and Evolution. 43 



strains have been preserved and the worse 

 exterminated ; and here I may allude again to 

 the nature of the so-called changes effected by 

 modern breeders. 



It is often said that breeders have changed 

 the whole character of a particular race, and 

 the success of their endeavours is often 

 considered a proof of the mutability of living 

 forms, whereas it is a proof of the contrary. 

 First. We must part off all that comes under 

 the head of functional gymnastics, so called by 

 Sanson, namely, all that refers to organs which 

 increase in power or virtue by activity, specially 

 the muscular and nutritive system ; all, in fact, 

 that is alterable in the same adult, of the same 

 sex, at the same season of year. This corre- 

 sponds roughly with Darwin's direct effects of 

 conditions of life and with his use and disuse. 

 These effects, though often inherited, are not 

 strictly race or family characters. Thus strains 

 of various races of any animal type may be 



