THE RAW MATERIALS OF EVOLUTION 107 



The first part of the Dutch botanist's great work 

 was published forty-three years after " The Origin 

 of Species," and there are many who regard the 

 Mutation Theory and Mendelism as the two 

 greatest steps of progress that have been made in 

 evolution-lore since 1859. Others, such as Alfred 

 Russel Wallace, the Nestor of the evolutionist camp, 

 are very far from sharing this view. In any case 

 we must try to understand what mutations are and 

 what their significance may be. 



The general idea is that novel characters may 

 suddenly appear, as it were, full-fledged, with con- 

 siderable perfectness from the moment of their 

 emergence, and without intergrades linking them to 

 the parents. Furthermore, the novel character of 

 the mutant, if we may use the word, is independently 

 heritable and does not blend ; it can be grafted 

 intactly on to another stock, or it can be dropped 

 out as such. Again, mutations are what may be 

 called qualitative, as contrasted with the fluctua- 

 tions which are quantitative. Thus, some of the 

 new evening primroses which De Vries got out 

 of his changeful stock of (Enothera lamarckiana 

 were very different from the parent type some had 

 few branches instead of many, some had small 

 flowers instead of large, some had quite different 

 leaves, and so on. Mutations have been recorded 

 for a number of other plants, such as violets and 

 shepherd's purse ; but the inquiry is still young. 



Among animals in nature we know as yet of few- 

 paper on " The Categories of Variation " (American Naturalist (1909), 

 vol. xliii. p. 277) : " Should it turn out to be derived from a mixture 

 of two or more forms, the mutation theory would be deprived 

 of some of its best evidence ; but there would still remain a con- 

 siderable number of mutations from pure ancestry," 



