70 WHAT EVOLUTION IS 



one, and instead of looking upon evo- 

 lution as a process so slow as to be 

 imperceptible, it was soon believed, as 

 a result of experimental test, to be 

 relatively rapid at least in particular 

 instances. In fact it was declared 

 that species might be created almost 

 over night. Such a radical change of 

 view had a profound effect on the 

 growth of the subject and though the 

 new programme may not have real- 

 ized all that was expected of it, it 

 brought the science into a vastly more 

 wholesome state and led to positive 

 growth of a most encouraging kind. 

 In this revival of activity all the 

 older explanations of evolution were 

 brought to the test with the result that 

 such ideas as Elmer's orthogenesis, 

 in which variation was supposed to 

 occur in definite and predetermined 

 directions, and Naegeli's idioplasm 

 theory, in which an internal perfect- 



