CHAPTER IV 



PHYLOGENY AND ONTOGENY OF THE NEURONA 



THE embryonic history of the neurona, from the 

 time it appears in inferior animals until it is seen 

 in man, is what constitutes its phylogeny. In 

 approaching such a subject in a book of this kind 

 it is enough to present it in outline, to give a 

 sufficient idea of how the intricate human brain 

 proceeds by successive complexities from a simple 

 element, that is to say, how the concordance of the 

 external with the internal is verified throughout 

 the animal kingdom. 



On this point Herbert Spencer says : "Physical 

 or psychical life is a combination of movements, 

 which correspond to another series of movements 

 or external facts. By the law of succession they 

 necessarily coexist internally, they are in in- 

 dispensable correspondence." In other words, the 

 human brain is a progressive complex association, a 

 plastic reproduction of the movements of universal 

 mechanics. 



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