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- 
188Qscar Hertwig: Ibid. II. P. 242, 243. 
