PHYLOGENY AND ONTOGENY OF NEURON A 55 



We see how, in the batrachi, the ramifications 

 of the peripheric prolongation begin to take 

 form in the body of the neurona (p) (fig. 7), 

 and how these ramifications are well defined 

 towards the cerebral surface, and also how the 

 central prolongation turns to the internal sheath 

 of the brain. 



The cerebral neurona of the batrachi is derived 

 from a more simple form, which is the bipolar. 



The Cerebral Cortex of Reptiles. Here the body 

 of the neuronas already begins to undergo modifi- 

 cation. The superior cerebral physiology of these 

 animals, compared with the anterior group, is seen 

 in the protoplasm increasing, and that in the form 

 most calculated to multiply its contacts, ramifying 

 as we see in fig. 8, d. 



This multiplication of the protoplasm constitutes 

 a most important differentiation, and its signifi- 

 cance will be better understood when we arrive at 

 the study of the neurona in man. 



The central prolongation also presents by its 

 ramifications a modification parallel to the body 

 and of equal significance, viz. the necessity of 

 multiplying the contacts so as to establish fresh 

 functional complexities. 



In the central prolongation, C (fig. 8), the first 

 ramifications appear. The peripheric prolongation 



