CH. XVII.] 



NERVE-CELLS. 



195 



of the cerebral cortex also prepared by Golgi's method (fig. 202, 

 p. 196). 



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 

 into branches, and the axis 

 cylinder process comes 

 off from the base of the 

 flask (fig. 203, p. 197). 



The study of the ner- 

 vous system by the valu- 

 able method introduced by 

 Golgi has led to some new 

 conceptions as to its struc- 

 ture and to a new nomen- 

 clature. 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 immedi- 

 ately into smaller branches 

 ending in arborescences of 

 fine twigs ; these branches, 

 which used to be called 

 protoplasmic processes, are 

 now termed dendrons and 

 the fine twigs dendrites ; 

 one branch becomes the 

 long axis cylinder of a 

 nerve-fibre, but it also ulti- 

 mately terminates in an 

 arborisation. It is called 



the axis cylinder process, or, more briefly, the axon. The term 

 neuron is applied to the complete nerve-unit, that is, the body of the 

 cell, and all its branches. Some observers have supposed that 

 the axis cylinder process is the only one that conducts nerve 

 impulses, the dendrons being rootlets which suck up nutriment for 

 the nerve-cell. This exclusive view has not, however, been generally 



o 2 



Fig. 201. Pyramidal wll of human cerebral 

 corU'X. Golgi's method. 



