II HISTORICAL 13 



long before he was capable of leading a separate 

 existence. As this conception ran counter to the 

 possibility of the inheritance of " acquired characters," 

 Weismann challenged the evidence upon which it 

 rested and showed that it broke down wherever 

 it was critically examined. By thus compelling 

 biologists to revise their ideas as to the inherited 

 effects of use and disuse, Weismann rendered a 

 valuable service to the study of genetics and did 

 much to clear the way for subsequent research. 



A further important step was taken in 1895, when 

 Bateson once more drew attention to the problem of 

 the origin of species, and questioned whether the 

 accepted ideas of variation and heredity were after 

 all in consonance with the facts. Speaking generally, 

 species do not grade gradually from one to the other, 

 but the differences between them are sharp and 

 specific. Whence comes this prevalence of discon- 

 tinuity if the process by which they have arisen is 

 one of accumulation of minute and almost imper- 

 ceptible differences ? Why are not intermediates of 

 all sorts more abundantly produced in nature than 

 is actually known to be the case ? Bateson saw 

 that if we are ever to answer this c^uestion we must 

 have more definite knowledge of the nature of varia- 

 tion and of the nature of the hereditary process by 

 which these variations are transmitted. And the 

 best way to obtain that knowledge was to let the 

 dead alone and to return to the study of the living. 

 It was true that the past record of experimental 

 breeding had been mainly one of disappointment. 

 It was true also that there was no tangible clue by 

 which experiments might be directed in the present. 



