MISPLACED RELIANCE. 153 



necessary but non-transmitted associations of 

 sensation and idea by his own experience. In a 

 well-known case, a blind man on gaining his sight 

 by an operation said that "all objects seemed 

 to touch his eyes, as what he felt did his skin " so 

 little had the universal experience of countless ages 

 impressed itself on his faculties. Under normal 

 healthy conditions use-inheritance is so slow in 

 its action that " several generations " must elapse 

 before it produces any appreciable effect, and then 

 that effect is only precisely what selection might be 

 expected to bring about without its aid. Strong 

 for evil and slow for good, it can convey epilepsy* 

 promptly in guinea-pigs, but transmits the acquire- 

 ments of genius so poorly that our best student 

 of the heredity of genius has to account for the 

 frequent and remarkable deterioration of the 

 offspring by a theory which is strongly hostile to 

 use-inheritance. It would tend to make organisms 

 unworkable by the excessive differences in its rate 



