82 ARE THE EFFECTS OF USE INHERITED ? 



MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO 

 SELECTION. 



Innumerable modifications in accordance with 

 altered use or disuse, such as the enlarged udders 

 of cows and goats, and the diminished lungs and 

 livers in highly bred animals that take little ex- 

 ercise, can be readily and fully explained as de- 

 pending on selection. As the fittest for the natural 

 or artificial requirements will be favoured, natural 

 or artificial selection may easily enlarge organs 

 that are increasingly used and economize in those 

 that are less needed. I therefore see no necessity 

 whatever for calling in the aid of use-inheritance 

 as Darwin does, to account for enlarged udders, or 

 diminished lungs, or the thick arms and thin legs 

 of canoe Indians, or the enlarged chests of moun- 

 taineers, or the diminished eyes of moles, or the 

 lost feet of certain beetles, or the reduced wings of 

 logger-headed ducks, or the prehensile tails of 



