CHAPTER IV 



MUTATION 



1. The Mutation Theory 



Among the possible kinds of variation already 

 hinted at are so-called mutations which are clearly 

 defined from the fluctuating variations to which 

 reference has just been made. 



Darwin was fully aware of the existence of muta- 

 tions or "sports" and incidentally gave time to 

 their consideration, but the great task which he 

 accomplished in such a masterly manner was to 

 overthrow the widespread and deep-seated belief 

 of his day in a sudden special creation of distinct 

 species. To this end he marshaled evidence in 

 support of the gradual transition of one species into 

 another, emphasizing fluctuations rather than muta- 

 tions which seemed to him to play a minor role in 

 the origin of species. 



It remained for the Dutch botanist Hugo de Vries 

 to analyze the character of mutations. There is 

 something distinctly suggestive of Darwin's method 

 in the fact that de Vries worked in silence for twenty 

 years before he gave to the world the *'Mutations- 

 theorie" with which his name will forever be con- 

 nected. 



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