Distribution of Energy Explains Ontogeny 51 



"in which nature destroys in a manner which may seem 

 to us cruel, cells which have just been produced." The 

 hypothesis of the distribution of trophic nervous energy 

 seems to us the only one which can give a satisfactory ex- 

 planation of this phenomenon. 



The struggle of the parts of the organism cannot in 

 fact be the exclusive cause of this involution of young 

 tissues. This struggle is not sufficient by itself to explain 

 the exactness of the epoch and of the stage of develop- 

 ment at which this physiological involution takes place. 

 Even if we were willing to admit that this struggle has 

 some effective participation in the production of this 

 phenomenon, we must nevertheless admit that in addition 

 an inciting ontogenetic stimulus, as Roux would say, 

 must at the appointed time exert its trophic action upon 

 the parts destined to victory, while it abandons others 

 previously favored, but which now are devoted to destruc- 

 tion. The distribution of trophic nervous energy with its 

 changes would thus always remain the only cause of the 

 phenomenon. 



But if ontogenetic physiological involutions are due to 

 the fact that the distribution of trophic nervous energy 

 abandons one region to turn to another, similar changes 

 and shifting of this distribution must then be likewise 

 the cause of all invaginations and evaginations, of all 

 morphological phenomena in general and, with much 

 probability, consequently, of those ontogenetic phenomena 

 also which are not exclusively morphological in nature. 



To produce each one of these serial ontogenetic mod- 

 ifications in the distribution of trophic nervous energy it 

 would suffice theoretically that at the required moment 

 there become active, were it only upon one certain point 

 of the circulatory system, a single new definite specific 



