Elasticity of Developing Organisms 93 



somatized at all, namely those whose function it is to 

 supply the reproductive cells with germinal substance. 

 And if the first nuclei become somatized by a process of 

 epigenetic nature, this process even though it involve the 

 entire organism, must leave the other nuclei unaltered. 

 But this would be possible only when this process is 

 dependent on influences proceeding from the zone of 

 germinal nuclei, and being exerted by it in such a manner 

 that the germinal substance concerned does not become 

 altered at all. 



The continuity of the germinal substance, the spec- 

 ificity of the nuclei, and the epigenetic nature of the 

 formative processes of organisms, these three concep- 

 tions which individually are favored by a great number 

 of biologists imply together the conception of centro- 

 epigenesis. 



Another fact which has been considered perhaps less 

 than it deserves, supports the hypothesis that the process 

 of development is not only of epigenetic nature, but also 

 depends upon influences coming off incessantly and suc- 

 cessively from a point which is external to all the trans- 

 forming parts, but which remains itself unchangeable; 

 namely the elasticity by virtue of which developing organ- 

 isms, much more than those completely developed, are 

 able not only to undergo without injury enormous changes 

 of form but also to resume their original form as soon as 

 the disturbing influence ceases. And just to this greater 

 elasticity of the young organism is to be attributed the 

 fact that it is much less plastic than the adult organism. 



In fact the centroepigenetic hypothesis would permit 

 one to deduce this a priori. For according to it the 

 young organism is so much more elastic, because in it 

 all the cells, being less specialized, are thus much more 



