io8 



Journal of Comparative Neurology. 



vous system of certain salamanders, as the neurocytes reach the 

 boundary of the cellular layer. 



Here are evidences of the plasticity of the nervous ele- 

 ments. Do they lose this property entirely after they have 

 reached maturity ? It has been pretty well demonstrated by 

 modern histological methods that these elements are morpho- 

 logically independent, and the hypothesis of co7itiguity or over- 

 lapping of the parts is now very generally accepted, instead of 

 the older view of continuity or direct anastomosis of one cell 



Fig. 7. 

 Fig. 7. After Berkley, showing a nerve cell with its processes (human); n, 

 neurite ; c, collateral ; </, d, d, dendrites ; g, gemmulce. Illustrating Berkley's 

 hypothesis of the way in which the nervous impulse may pass from one nerve 

 cell to another by contact of the gemmulte. 



with another. Contact of one element with another is sufficient, 

 it is believed, for the transference of a nervous impulse. The 



