222 STUDENTS HISTOLOGY 



TYPE I. The cell has, besides the protoplasmic processes, an 

 axis - cylinder process which becomes continuous with the axis- 

 cylinder of a nerve -fiber usually having a considerable length. 

 Minute offshoots are given from the axis - cylinder process, which 

 are called collaterals (Fig. 139, A). 



TYPE II. In this case the axis -cylinder process divides repeat- 

 edly and soon after leaving the ganglion -cell, forming a network 

 within the nerve -center (Fig. 139, B). 



A ganglion -cell with its axis -cylinder process is called by many 

 writers a neurone. In the case of some of the medullated nerve- 

 fibers proceeding from the cerebro - spinal centers, the terminal 

 distribution of the axis -cylinder may be as much as a meter 

 distant from the ganglion -cell (Fig. 140). 



NEUROGLIA 



The brain and spinal cord have a supporting framework of 

 ordinary connective tissue which enters at the surface from the 

 pia mater. They possess, besides, a special form of supporting tis- 



FIG. 141. NEUROGLIA FROM BENEATH THE PIA MATER OF THE SPINAL CORD. 



(X 400.) 



A. Network of neuroglia-fibrils. 



B. Spider (Belter's) cells. 



C. Nerve-fibers in T. S. 



sue called neuroglia. It ctmsists of a fine reticulum produced by the 

 interlacing of large numbers of delicate processes, which arise from 

 neuroglia cells. These cells have a stellate outline, and, with their 



