DARWIN, NAEGELI AND DE VRIES 129 



ment ; the idioplasm of every species not only contains 

 the micellar strands which characterise the species, 

 but it contains also, potentially, the strands which 

 characterise the one or several species which it will 

 father. External conditions concur with internal 

 tendencies in adapting organs and functions to life's 

 needs, but cannot themselves initiate any evolution. 

 Evolution results from an internal tendency toward 

 progress and perfection. In the course of phylo- 

 genesis, new micellar filaments add themselves to the 

 original ones, the structure acquires more complexity, 

 characters and functions become differentiated, be- 

 ings become more and more perfect. External con- 

 ditions influence this progress in such a way as to 

 insure its usefulness ; they are the origin of adaptation 

 but their influence can only exert itself upon what a 

 progressive evolution has already created. 



Naegeli's system, complex and inclusive, has con- 

 tributed two new ideas which later theorists have 

 taken up and developed : First, the idea of two kinds 

 of protoplasm, of which one only contains the various 

 characters of the organism, and secondly, the idea of 

 elementary characters which, through their combina- 

 tions, produce the greatest variety of properties. 

 This last suggestion in particular has made the idea 

 of representative particles more easily acceptable, for 

 it removes the necessity of supposing that those par- 

 ticles are present in unlimited numbers. Were it not 



