18 



ANATOMY OF THE CENTEAL XEEVOUS SYSTEM. 



The real nerve-tissue which fills the meshes of the figitred net-work 

 consists of ganglion-cells and nerve-fibers. The form of the ganglion-cells 

 is exceedingly varying. There are small, nearly-spherical forms with few 

 processes, and there are multipolar cells with numerous processes and twenty 

 times as large as the ones just described. In the lobes of the N. vagi of the 

 Torpedo and in the Medulla of the Cyclostomii are ganglion-cells so enor- 



Kg. 5. — Epithelium and neuroglia surrounding the central canal. Section 

 through the spinal cord of a human embryo of twenty-three centimeters' length. 

 Prepared by the Golgi-Cajal method. Note that only a part of the cells have 

 taken the silver precipitate, — a marked advantage mentioned above, — for only 

 through this is it possible to recognize what belongs to any one cell. (After 

 Lenhossek.) 



mous that one may easily see them with the unaided eye. Indeed, in the 

 spinal cord of the electric eel — 21 alapterurus — are two isolated ganglion- 

 cells of such size that the immense single nerve-fiber which each sends out 



