NERVE-CELLS. 203 



used the terra nerve-cell is conveniently applied to the main 

 body of these cells, regardless of the extended processes. 

 Such a term as neurosome would, perhaps, be a better desig- 

 nation for the nerve-cell body. Nerve-cells are ordinarily of 

 large size, and are situated in the ganglia and cerebro-spinal 

 centres. Their cytoplasm usually consists of a network of 

 fibrils (spongioplasm), in the meshes of which is a more fluid, 

 homogeneous protoplasm (hyaloplasm), sometimes called 

 neuroplasm. 



The cell-bodies often contain granules (chromophilic gran- 

 ules) which stain deeply with various dyes, especially basic 

 stains ; pigment is also sometimes present. There is no definite 

 cell-envelope. 



Nerve-cells possess each a large vesicular nucleus, usually 

 poor in chromatin, and hence not staining deeply ; within the 

 nucleus is a large nudeolus. In shape nerve-cells vary, being 



FIG. 76. 



Body of multipolar nerve-cell from spinal cord (Nissl's stain), showing details of 

 the structure (Ramon y Cajal). a, neurite; 6, c, cytoplasm, containing coarse 

 chromophilic granules ; d, nucleus, with nucleolus ; e, dendrite. 



spherical (ganglia), oval, fusiform, pyramidal (cerebrum), or 

 stellate (spinal cord). 



