CH. XVII.] 



NERVE-CELLS. 



193 



The majority of nerve-cells found in the body are multipolar. 

 Here the cell becomes angular or stellate. Fig. 199 shows the 

 usual form of cell present in sympathetic ganglia. From the 

 angles of the cell, branches originate ; the majority of these 

 branches divide and subdivide until they end in an arborescence 

 of fine twigs or fibrils ; but one process, and one process only, of 

 each cell becomes the axis cylinder of a nerve-fibre. 



fig. 190. An isolated sympathetic franglion cell of man, showing sheath with nucleated- 

 cell lining, B. A. Ganglion cell, with nucleus and nucleolus. C. Branched process. 

 D. Axis cylinder process. (Key and Ectzius.) x 750. 



Passing next to the central nervous system, we here again find 

 the multipolar cell is the principal kind present. 



The next figure (fig. 200) shows one of the typical multipolar 

 cells of the spinal cord. Here again, only one process (a) becomes 

 the axis cylinder of a nerve-fibre, and the others break up into 

 arborisations of fibrils. The cells have a finely fibrillar structure, 

 and the fibrils can be traced into the axis cylinder process and 

 the other branches of the cell. IJetween the fibrils the protoplasm 

 of the cell contains a number of angular or spindle-shaped masses, 

 which have a great affinity of basic aniline dyes like methylene 

 blue. They are known as .V/W# granule*. These nerve-cells 

 also contain, especially in the adult, granules of pigment, usually 

 yellow, the nature of which has not been determined. 



K.P. o 



