DARWIN, NAEGELI AND DE VRIES 125 



order to answer the question, Naegeli imagines molec- 

 ular forces which have their origin, not in the isolated, 

 powerless micella?, but in clusters of micella? grouped 

 in a certain manner. Upon these groups of micella? 

 life is absolutely dependent. 



Every group of micella? forming a harmonised unit 

 determines only one character of one living thing. 

 There should be apparently as many groups of micel- 

 la? as there are characters; but the number of charac- 

 ters is so large that the idioplasm could not contain 

 all the groups representing them; this new difficulty 

 is solved through another clever hypothesis: The 

 only necessary groups are those which determine the 

 few characters designated as elementary characters; 

 all other characters, that is the complex characters, are 

 constituted by various combinations of the elementary 

 ones and are therefore imparted to the living tiling by 

 the simultaneous action of the groups of micellae cor- 

 responding to their component elements. 



How are the micellar groups disposed in the con- 

 tinuous idioplasmic network intersecting the whole 

 organism? The answer Naegeli gives to the question 

 is dictated by the necessity of accounting for the fact 

 that one fragment of an animal or of a plant (egg- 

 cell, spermatozoon, spora, bud, twig) can reproduce 

 by growth the entire individual with all its character?,. 

 This leads him to think that such a fragment contains 

 all the micellar groups determining every character. 



