272 Theories Treating of Inheritance 



whatever; but natural selection (which acts in each cell 

 of the organism among the different plastidular varia- 

 tions) intervenes and fixes only those which are adapted 

 to the new conditions of equilibrium." 206 



We would just remark here, that the alteration 

 undergone by the molar movements within each cell will 

 be different in the different cells. For it would be incom- 

 prehensible how in the very complex structure of the 

 organism, a local change of form, imposed by external 

 agents, could induce quite identical alterations in the 

 molar movements of all the other cells of the body 

 indiscriminately. Consequently the alterations of the liv- 

 ing substance which internal natural selection preserves 

 as fittest will likewise be different in different cells. How 

 then can there be any question of the survival, in con- 

 sequence of this internal natural selection, of one single 

 plastidular variation identical at all points of the 

 organism ? 



LeDantec, like Hertwig, has recourse to the example 

 of immunization. But as we have already seen, this 

 case is quite different from the more or less local changes 

 of form, which individuals experience in consequence of 

 particular functional adaptations. In the case of immuni- 

 zation the transforming cause, i. e. antibacterion, is the 

 same for all cells. In the case of a morphological 

 alteration on the contrary the transforming cause, that 

 is, as we would concede it, the variation experienced by 

 the molar movement concerned, is different in each cell. 



Even if one were willing to assume an identical 

 variation of the living substance at all points of the 

 organism indiscriminately, that would not explain the 



80a Le Dantec : Ibid. P. 270, 298. 



