Chap, il] OF CELLS AND OF NERTOUS FIBEES. 37? 



The nervous cells continue always with one or more fibres. 

 They are thus called, according to the number of these fibrous 

 prolongations, unipolar, bipolar, multipolar. Cells called apolar, 

 without nervous prolongations, are long admitted : but their 



Tio. 67. 



Ganglionary moltipoIaT cell of the spinal marrow of tlie ox, with a rounded nucleus and a 

 nucleole : a, cylinder axis ; h, prolongations of the cell finely striated and flbrillaiy, — 

 Very greatly magnified. 



existence is very problematical. The nervous cells having a 

 greyish tint, which they owe to their contents, the regions of 

 the nervous centres when they are gathered together in great 

 number have the same colour. Thus is constituted the grey 

 ^lervous substance, which we find on the surface of the brain and 

 in the central part of the .spinal marrow in the mammifers, and 

 so on. 



