STRUCTURE OF THE NERV( 



ITEM 



and firm, closely adhering, membranous envelope, consisting of dense areolar 

 tissue; this sheath is continuous with the perineurium of the nerves, and sends 

 numerous .processes into the interior to support the bloodvessels supplying the 

 substance of the ganglion. 





FIG. 637. Muscular fibers of Lacerta riridis with the terminations of nerves, a. Seen in profile. P, P. The nerve 

 end-plates. S, S. The base of the plate, consisting of a granular mass with nuclei, b. The same as seen in looking at 

 a perfectly fresh fiber, the nervous ends being probably still excitable. (The forms of the variously divided plate can 

 hardly be represented in a woodcut by sufficiently delicate and pale contours to reproduce correctly what is seen in 

 nature.) c. The same as seen two hours after death from poisoning by curare. 



In structure all ganglia are essentially similar, consisting of the same structural 

 elements viz., nerve cells and nerve fibers. Each nerve cell has a nucleated sheath 

 which is continuous with the neurolemma of the nerve fiber with which the cell is 

 connected. The nerve cells in the ganglia of the spinal nerves (Fig. 638) are pyri- 

 form in shape, and have each a single process. A short distance from the cell and 

 while still within the ganglion this process divides in a T-shaped manner, one 

 limb of the cross-bar turning into the medulla spinalis, the other limb passing out- 



Fio. 638. Transverse section of spinal ganglion of rabbit. A. Ganglion. X 30. a. Large clear nerve cell. 6. 

 Small deeply staining nerve cell. c. Nuclei of capsule. X 250. The lines in the center point to the corresponding 

 cells in the ganglion. 



ward to the periphery. In the sympathetic ganglia (Fig. 639) the nerve cells are 

 multipolar and each has one axis-cylinder process and several dendrons; the axon 

 emerges from the ganglion as a non-medullated nerve fiber. Similar cells are found 

 in the ganglia connected with the trigeminal nerve, and these ganglia are therefore 



