Driesch 245 
For the specific protoplasm which a certain cell has 
already acquired at a given moment of ontogeny by re- 
ceiving only one certain stimulus corresponding to its 
immediately preceding specificity, would really become 
the special cause by which among all possible nuclear 
energies only that one becomes liberated which should 
become active at that instant. The activation of this new 
nuclear energy would in its turn modify the specificity of 
the protopiasm of this cell and of its immediate descend- 
ants; and this protoplasm so altered would then become 
the cause of the reception of a new specific stimulus and 
of the consequent liberation of the next required nuclear 
energy; and so on up to the completion of development. 
Each cell of any given ontogenetic stage would thus 
come to carry in itself all that is necessary to determine 
its own future character and that of its most remote 
descendants, with the exception of the various stimuli 
which it is the duty of the protoplasm to select and to 
receive. 
One thing is not quite clear in this. Do these liberat- 
ing causes of the different nuclear energies, that is these 
stimuli, among which each protoplasm should select and 
receive only those belonging to it, come only from the 
world outside the organism, or also from the reciprocal 
actions of the individual parts in the interior of the 
organism? In the first case it would be necessary to place 
Driesch among the out and out evolutionists; in the 
second, his theory would be a mixed one, that is it would 
rest upon phenomena of evolutionistic nature combined 
with others of epigenetic nature. 
We shall not set forth any further here what enor- 
mous difficulties one would encounter in either case if one 
sought to build up in accordance with this theory any 
