NORMAL HISTOLOGY. 



FlG - 82 - 



processes is only apparent, being due either to mutilation or to the 

 process lying without the plane of the section ; where processes are 

 really wanting, an immature or pathological condition must be 

 suspected. 



The processes of nerve-cells are of two principal kinds the 

 branched protoplasmic and the axis- cylinder (Deiters's) pro- 

 cesses. When a cell possesses but one, this is always an axis- 



cylinder process. The proto- 

 plasmic processes rapidly 

 undergo dichotomous di- 

 vision, splitting up and sub- 

 dividing until the resulting 

 branches form rich net-works 

 of slender protoplasmic 

 threads, which frequently 

 interlace, but probably never 

 actually join, with similar 

 fibrils of adjacent cells. 

 Nerve-cells, in one sense, are 

 but nucleated local accumula- 

 tions of the interfibrillar pro- 

 toplasm, which latter may be 

 termed neuroplasm (K61- 

 liker) ; the large striated 

 multipolar ganglion-cells may 

 be regarded as switch-boards 

 for the redistribution of the 

 numerous ultimate fibrillae 

 continued into the axis-cylin- 

 ders. The fibrillae pass off in 

 divergent paths, along the 

 several processes of the cell, 

 to form new combinations and 

 relations. 



The peculiarities formerly supposed to constitute the distinguish- 

 ing characteristics of the axis-cylinder processes are no longer suf- 

 ficient in the light of recent advances in our knowledge regarding the 

 structure of the nervous system. The investigations of Golgi and 

 others have shown that, in addition to greater delicacy and a straighter 

 course, the axis-cylinder processes present variations which separate 

 ganglion-cells into two groups cells of the first and cells of the 

 second type. 



Nerve-cells of the first type include elements, as those of the 

 motor areas, possessing the characteristic axis-cylinder processes 



Nerve-cell from the cerebral cortex, exhibiting the 

 striations of the protoplasm and the conspicuous char- 

 acter of the nucleus and the nucleolus : /, pigment- 

 granules : a, axis-cylinder process ; b, I, apical and 

 lateral protoplasmic processes. 



