DARWIN, NAEGELI AND DE VRIES 131 



of micellar cords without which neither ontogenetic 

 development, nor heredity, nor variation can be ex- 

 plained. The absurdity of that premise compromises 

 the whole theory. It is not worth our while to ex- 

 amine in detail his theory of phylogenetic evolution; 

 "internal evolutionary tendencies" explain nothing 

 unless we are told in what well-known organic prop- 

 erty they have their origin. 



De Vries designates his theory as pangenesis and 

 considers it as a direct derivation from Darwinism. 

 While Darwin's gemmules, however, represent the 

 various cells of the organism, De Vries "elementary 

 units" or "pangenes" represent characters and are 

 therefore more similar to Naegeli's micellar groups. 



De Vries has contributed very little to the solution 

 of the question at issue. Like the gemmules and mi- 

 cellar clusters, the pangenes are particles which de- 

 termine the character of the cells, but unlike the gem- 

 mules, they do not distribute themselves through the 

 organism and they differ from Naegeli's micellar 

 groups in not being made up of smaller units. The 

 pangenes are located in the nucleus; every nucleus 

 contains a complete series of them representing all 

 the potential or actual characters of the organism. 

 Previous to the cleavage of a cell, the pangenes of 

 the nucleus multiply also by cleavage so that every 

 one of the daughter-cells may receive a complete 

 series of them. If a cell becomes differentiated 



