26 Indications of Continued Formative Influence 
to be somatized accidentally remain isolated, in which 
case the activation of their potential germinal energies 
would be permitted, which might have been impossible 
had they remained united with the other blastomeres or 
cells. 
The possiblity of such receptive indifference toward 
somatizing stimuli in nuclei which if they were isolated 
or in other conditions would on the contrary possess and 
give practical demonstration of very definite specific 
qualities, is indicated by those cases in which all the 
nuclear material of the post generated half embryo is 
furnished by the half already developed. 
Indeed it often happens that on the side operated upon 
the nutritive yolk alone is utilized; and into this latter 
emigrate nuclei formed by normal division of the nuclei 
of already somatized cells in the developed half of the 
egg. And these emigrated nuclei then bring about the 
division of the yolk mass of the part operated upon into 
small indifferent cells only: ‘With the formation of a 
right or left half embryo,’ Roux observes in a later 
study, “the formative capacity of the uninjured half of 
the egg is not yet exhausted. On the contrary certain 
experimental results permit the conclusion that in many 
cases there is an emigration from it of nuclei, and 
perhaps indeed, of a little protoplasm also, going out 
from those points which by the accident of position have 
the most intimate contact with the side operated upon, 
toward the contiguous half of the egg deprived of its 
own capacity of development. These nuclei become 
distributed throughout the whole of the large mass of 
yolk and thereupon follows later a breaking up of the 
half operated upon into cells, and this is not as in normal 
division a division of the whole mass first into two nearly 
