CH. XVI.] NERVE-CELLS 187 



shape. They are especially large and numerous in what are called 

 the motor areas of the brain. The apex of the cell is directed to the 

 surface ; the apical process is long and tapering, and finally breaks 

 up into fibrils that lie parallel to the surface of the brain (tangential 

 fibres). From the lower angles and other parts branching processes 

 originate ; the axis cylinder comes off from the base of the pyramid. 

 (See figs. 181, 182). 



The grey matter of the cerebellum contains a large number of 

 small nerve-cells, and one layer of large cells. These are flask-shaped, 

 and are called the cells of Purkinje. The neck of the flask breaks up 



Axon 



FIG. 183. Cell of Purkinje from the human cerebellum. Golgi's method. 

 (After Szymonowicz.) 



into branches, and the axis cylinder process comes off from the base 

 of the flask (fig. 183). 



The whole nervous system consists of nerve-cells and their 

 branches, supported by neuroglia in the central nervous system, and 

 by connective tissue in the nerves. Some of the processes of a 

 nerve-cell break up almost immediately into smaller branches ending 

 in arborescences of fine twigs ; these branches, which used to be 

 called protoplasmic processes, are now termed dendrons. One branch 

 becomes the long axis cylinder of a nerve-fibre, but it also ultimately 

 terminates in an arborisation ; it is called the axis cylinder process, 

 or, more briefly, the axon. The term neuron or neurone is applied to 



