PROPERTIES OF THE NERVE CELL. 



125 



axis of the central nervous system. The sensory impulses brought 

 to the cell by the process arising in the peripheral tissue doubtless 

 pass into the body of the cell before entering the process that 

 leads to the cord or brain, that is, it is not probable that the im- 

 pulse passes from one process to the other at the T junction, since 

 the really conducting elements in the axis cylinder, the neurofibrils, 

 are not in connection at this point but in the network or reticulum 

 of the cell itself. 



II. The multipolar cells. The processes of these cells fall into 

 two groups: the short and branching dendrites with an inner 

 structure resembling that of the cell body, and the axon or axis 

 cylinder process (Fig. 54). According to the structure of this last 

 process, this type may be classified under two heads : Golgi cells of 



Fig. 55. Bipolar cells in the posterior root ganglion. Section through spinal gan- 

 glion of newborn mouse (Lenhossek) : a, The spinal ganglion ; 6, the spinal cord ; c, the 

 posterior, d, the anterior root. 



the first and the second type. The cells of the first type are charac- 

 terized by the fact that the axon leaves the central gray matter and 

 becomes a nerve fiber. This nerve fiber within the central nervous 

 system may give off numerous collaterals, each of which ends in a 

 terminal arborization. By this means the neurons of this type may 

 be brought into physiological connection with a number of other neu- 

 rons. This kind of nerve cell is frequently described as the typical 

 nerve cell. Golgi supposed that it represents the motor type of cell, 

 and this view is, in a measure, borne out by subsequent investiga- 

 tion. The distinctly motor cells of the central nervous system 

 such, for instance, as the pyramidal cells of the cerebral cortex, the 

 anterior horn cells of the spinal cord, the Purkinje cells of the 

 cerebellum all belong to this type. But within the nerve axis 



