Hertwig 237 



nature of which will be conditional upon the general state 

 of the organism ; this action will be felt by each individual 

 part and in so far as it amounts to a lasting modification 

 of the idioplasm it becomes a newly acquired character." 



At every fresh modification of the general state of the 

 organism, "the total heritage of the organism becomes 

 enriched by a new member, by a new anlage which mani- 

 fests itself again in the development of the succeeding 

 organism, in that now the newly developing individual 

 reproduces more or less 'from the germ out* or from 

 internal causes the character which its parents had ac- 

 quired during their lives from intercourse with the outer 

 world." 183 



Does Hertwig in this say that the reproductive sub- 

 stance is constituted by a heaping up of a whole series of 

 material modifications, which correspond to the successive 

 phylogenetic general states of the body, and constitute as 

 many potential tendencies ? 



That is hard to decide, because all that relates to his 

 conception of the idioplasm structure is obscure and often 

 contradictory. Thus in some places he seems to admit 

 that his idioplasm may be constituted by preformistic 

 germs, so that his theory would belong with that of De 

 Vries to the group of theories of epigenesis with pre- 

 formistic germs. In other places on the contrary where 

 he speaks of general states of the idioplasm, and other 

 similar things, every idea of preformistic germs seems to 

 be excluded, so that his theory appears to be very similar 

 to those of epigenesis without preformistic germs, like 

 that of Spencer. The same is true also of this heaping up 

 of different material modifications representing the suc- 



188 Oscar Hertwig: Ibid. II. P. 242, 243. 



