Hertwig 230 
during ontogeny one after another in the same order as 
in phylogeny? How does each of the successive general 
states of the idioplasm, identical for the entire organism, 
exert upon each individual cell so many special actions, 
which are not only quite different from one another but 
also are the exact reverse of those which by their union 
had produced this general state during phylogeny ? 
But however that may be, it is not at all certain that 
Hertwig accepts this heaping up. For, as we have said 
above, if he seems in certain places inclined to accept it, 
he appears in others to reject it absolutely. 
He seems to accept it for example when he approves 
and adopts the following passage from Nageli: 
“The unfolding of the anlagen of the idioplasm fol- 
lows faithfully the phylogenetic order. While the or- 
ganism, developing in ontogeny, runs successively 
through the stages through which its phylogenetic stem 
has run, the idioplasmatic anlagen become developed in 
just that order in which they came into existence.” 
And this conception appears confirmed in the follow- 
ing words of Hertwig: “On account of the progressive 
multiplication of the cells, their combined action is con- 
stantly producing new embryonic states in the same serial 
order as that in which they appeared during phylogeny. 
The individual cells are brought into new relations to one 
another and to the external world, and through these 
successive reciprocal relations the anlagen latent in the 
cells become awakened.” 184 
In other places on the contrary he seems to reject 
completely this heaping up of a whole series of anlagen, 
of which each should correspond to the phylogenetic state 
184Qcscar Hertwig: Die Zelle und die Gewebe. II. P. 251, 253. 
