Interpretation of Partial Formations 63 
half of the egg affording such a definite deutoplasmic 
disposition. 
So it becomes clear that when once the development 
of the uninjured half of the egg has commenced, the 
central zone concerned, even though it may be exactly the 
same as in the complete embryo, would activate only the 
specific potential energies proper to the corresponding 
half embryo and would produce only a half formation. 
This half formation no matter how independent the 
great correlation networks might be, could nevertheless 
at each instant of its development, render the system of 
nuclear actions and reactions an incomplete one, without 
equilibrium, because at the plane of separation there 
would not be opposed to its own nervous tensions any 
equivalent system of tensions of the absent half. This 
incomplete system of nuclear tensions, not of itself in 
equilibrium, could nevertheless be prevented, even though 
only transiently, from equilibrating itself normally, by 
the special distribution of the nutritive yolk and by the 
presence of the injured half of the egg, still placed op- 
posite that which is developing. But as soon as the con- 
tinual increase of energy in the nuclear system overcomes 
these artificial barriers, equilibrium is once for all upset 
and postgeneration will appear. 
It is necessary nevertheless to note that some demi- 
monsters which proceed almost to the completion of their 
development would seem on the contrary to indicate for 
this incomplete system of nuclear actions and reactions a 
practical equilibrium existing from the commencement 
and persisting through all the stages of development. 
The typical example of these demimonsters is the famous 
Hemitherium anterius which Roux so thoroughly 
describes. It is constituted by the almost fully developed 
