68 SUPER-ORGANIC EVOLUTION 



Neuroglia 



The cells of the neuroglia are like those of 

 epithelial origin. In fig. 3A we see some cells 

 which serve as a support to the young neurona, 

 and these, which owe their origin to the ectoderm 

 of the gastrula, are those that, with a less degree 

 of differentiation, are known later by the name of 

 neuroglia. 1 



In the diagrams with the sketches of the cerebral 

 cortices of batrachi, reptiles, birds, and mammiferse 

 we see these neuroglia cells, which, according to 

 the majority of histologists, constitute the separat- 

 ing element of the nerve-currents in the brain. 

 One can conceive that, the more delicate the brain 

 and the higher it ascends in the animal series, the 

 more complicated is the neuroglia cell for its adjust- 

 ment to the morphology and functioning of the 

 neurona, so as to avoid the infiltration of currents 

 which would weaken cerebral action. 



1 A cell that serves at once to sustain and isolate the neurona. 



