128 THE ORIGIN OF THE NERVOUS SYSTEM 
condition at higher levels. In other words, the primi- 
tive type of axiate physiological integration is similar 
to the autocracy in social integration, but in the devel- 
opment and evolution of the organism, as in social 
development and evolution, there is a gradual approach 
toward democracy. 
While the evidence is less extensive, the data of 
normal development and of experiment indicate that 
the ontogenetic relation of the postcephalic regions of 
the central nervous system to regions lateral and dorsal 
(invertebrates) or ventral (vertebrates) to them is 
similar to the relation of the cephalic to the post- 
cephalic regions. These postcephalic regions of the 
central nervous system apparently arise from the high 
ends of the symmetry gradients (Figs. 13-17), and so 
far as these regions are dominant they must be primarily 
independent of the parts which they dominate. 
THE SIGNIFICANCE OF THE FACTS 
It is a fact of considerable theoretical interest not 
merely to the biologist but to the psychologist as well 
that the cephalic region of the central nervous system 
arises from that region of the body which primarily is 
most intensely active and most completely independent 
of other parts. In fact the development of the central 
nervous system and particularly of its cephalic portion 
represents that physiological and morphological reaction 
of animal protoplasm which is least complicated by 
physiological correlation with other parts and most 
directly related to external exciting factors. The cen- 
tral nervous system arises from the higher levels of the 
chief axial gradients in the organism, and these represent 
