34 E VOL UTION AND DISEASE. 



particular trades, as those of watchmakers, jewellers, 

 ivory carvers, &c., or the precision of artists and sculp- 

 tors, and, in a more marked sense, the keen ear of 

 musicians, and the wonderful faculty displayed by 

 mathematicians in their marvellous dealings with num- 

 bers and calculations, have all been slowly attained by 

 the persistent transmission of the effects of increased 

 use. 



