Method of Origin of New Species and Structures 419 



Such new kinds were supposed by de Vries to be species, of an 

 ultimate or elementary sort, and, in reference to their mode of 

 origin he designated them mutants, while the parent species he 

 described as being in mutation. As to the exact relation of muta- 

 tion to evolution, that was supposed by de Vries to be this, that 

 mutants, or elementary species, and not single variations, are 



FIG. 173. Groups of the mutants of (Enothera, growing in de Vries' experimental garden 

 at Amsterdam. The parent species, (E. Lamarckiana, is the single one on the extreme 

 left. In one group two flowers are covered with bags for experimental purposes. Ob- 

 serve the distinctness of the groups from one another, in conjunction with a certain 

 amount of variability within each group. (Photographed from a colored picture in 

 de Vries' book, The Mutation Theory, Vol. II.) 



the material upon which selection works. Darwin thought the 

 basal variations were mostly single, finely-graded, and more or 

 less unstable, while de Vries offers instead collections of varia- 

 tions large, definite and permanent; but otherwise their views are 

 in full harmony, both agreeing that natural selection is the final 

 factor which determines survival. Like variations, the mutations 



