62 Indications of a Central Zone of Development 
another, it follows that at least each quarter of the 
embryo must have its own system of correlation networks 
independent of the other quarter systems. But the four 
quadrants have one zone which is common to all. Con- 
sequently at least these four independent systems of cor- 
relation networks for the four quadrants must come off 
from this common zone. 
This suffices to warrant the statement that this latter 
must belong to a central zone of development, in the sense 
which we have set forth above; and that from this zone 
must branch off and diverge independently of one another 
the different great correlation networks or principal 
branches for the general distribution of nervous energy. 
These latter divide further into progressively smaller 
ramifications, one could almost say just as the great 
arterial trunks coming off from the heart continually sub- 
divide down to the terminal capillary vessels. 
It is nevertheless advisable to study these phenomena 
more closely. We must postulate that each of the two 
blastomeric nuclei obtained in the frog’s egg after the first 
segmentation, when it once becomes completely isolated, 
is capable of giving rise to a complete embryo. But in 
the experiments of Roux, the disposition of the nutritive 
yoke or deutoplasm in the uninjured blastomere remains, 
thanks to the retention of its place by the injured blasto- 
mere, the same as the disposition which would have 
existed in this same blastomere if development had pro- 
ceeded normally. Therefore, of all the specific potential 
energies which the uninjured blastomeric nucleus would 
be capable of activating successively, there would com- 
mence and continue to be activated only those which in 
normal development would have flowed directly into the 
