co-tempory of Lamarck, had suggested that developments 

 might occur suddenly by leaps. Both Huxley and Galton 

 believed that nature makes jumps now and then, while 

 Bateson had accumulated a large number of instances of 

 discontinuous variations, and was convinced that such var- 

 iations were common. The importance of discontinuous 

 variations as factors in evolution was clearly shown by 

 Hugo DeVries in his "Mutations Theory," published in 

 1901. (Fig. 10). 



According to this theory species have arisen after the 

 manner of spontaneous or discontinuous variations in contra- 



A>Vv-^^'^'i&fc^ . 



Fig. 10.— HUGO DeVRIES 



distinction to their origin by the selection of fluctuating or 

 continuous variations, as proposed by Darwin. 



It is now recognized that Natural Selection does not ex- 

 plain the origin of species or that of adaptations, but rather 

 the persistence of adaptations and the elimination of the un- 

 fit. DeVries' Mutation Theory attempts to account for the 

 origin of specific characters. 



"Mutations arise suddenly and without any obvious 

 cause; they increase and multiply because the new charac- 



65 



