Blastomeres Which Acquire Formative Control 25 
to the effective germinal zone, leads us to a second 
hypothesis, namely: that the especially germinative 
energies of those nuclei destined to become somatic may 
be once for all silenced, that is once for all put in a 
potential state incapable of activation, on account of the 
preponderance which the nuclei that go to form the 
effective germinal zone or central zone acquire. 
In fact we can suppose that the first blastomeric nuclei, 
though exactly alike qualitatively, are different quanti- 
tatively, that is to say are furnished with amounts of 
energy which do not chance to be quite the same in all, 
perhaps on account of special conditions of nutrition or, 
perhaps, on account of special conditions of the proto- 
plasm in which they are placed. Then, as soon as the 
moment comes when because of the nature of the com- 
mencing transformation, such as perhaps invagination or 
some such thing, embryonal development can no longer 
proceed after the same fashion in all cells, certain ones 
will necessarily gain the upper hand, namely those which 
possess more potential energy. 
The other blastomeres whose nuclei would no longer 
be able to activate their germinal energies will from now 
on conduct themselves, in relation to the stimuli of the 
nuclei of those blastomeres which constitute the central 
zone of development, just like cells with indifferent 
nuclei. And with the progressive somatization of these 
latter the mass of their respective specific elements to 
which is due the persistence, potentially at least, of their 
germinal energies, will gradually diminish and finally 
disappear. 
There is only a single conceivable exception, namely 
the case in which at the beginning of development or in 
inferior forms, these blastomeres or cells just beginning 
