TWENTIETH CENTURY EVOLUTIONISM 87 



paleontology and of pathology in the universities of Berlin* 

 Paris, Vienna, Strasburg, Tubingen, Amsterdam, Columbia 

 University, etc. 1 



Even the once indisputable theory of a gradual 

 evolution was now disregarded by many of the 

 foremost scientists, and the "saltatory theory" or 

 "theory of mutations," was widely accepted in 

 its stead. It was popularized in particular by 

 the efforts of De Vries. 2 Such changes as may 

 have taken place were now explained, not any 

 longer by a slow process of evolution, which be- 

 fore it had been heresy to deny, but by a varia- 

 tion said to have appeared suddenly. The new 

 form was thus thought to have at once been fully 

 differentiated from all previous forms, as a so- 

 called "sport" or "monstrosity" may be unex- 

 pectedly born at any time. But the new form was 

 then supposed to have remained permanent. 

 Whatever truth this hypothesis may contain, it 

 obviously is no more capable of any final proof 

 than the theory of slow mutations which it re- 

 places. Nature refuses to yield up her secret. 

 We see the new species appearing with a startling 

 suddenness, and how they came to be we do not 

 know. The rest is guess-work, more or less 

 shrewd, with a measure of probability in a very 

 restricted sphere. 



The hypothesis that new species suddenly 



1 Darwinism To-day," p. 26. 



'"Die Mutationstlieorie" (1901-1903). 



