THEORY OF EVOLUTION 



153 







Fui. 78. A race nf fiirn reai-ed under different conditions. 



it contains only a i:)ai-t of the trutli. Any one 

 who repeats for himself this kind of selection 

 ex2:)ei-iment will find that while his average class 

 will often change in the direction of his selec- 

 tion, the process slows down as a rule rather 

 suddenly (fig. 80). He finds, moreover, that 

 the limits of variability are not necesarily trans- 

 cended as the process continues even although 

 the average may for a while be increased. JMore 

 tall men may be produced by selection of this 

 kind, but the tallest men are not necessarily any 

 taller than the tallest in the original population. 



