THEORY OF EVOLUTION 



153 





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Vu,. 78. Corn rcarod iiiidcr (litKi't-nt ((m.hii m.h^. (^At'ter 

 Blakeslee.) 



it contains only a j^art of the trutli. Any one 

 who repeats for himself tliis kind of selection 

 experiment will find that wliile 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 variahilitv are not necesarilv trans- 

 cended as the process continues even although 

 tlie average may for a while be increased. JNIore 

 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. 



