286 



NERVE-TISSUE. 



brain and spinal cord j they vary greatly in size and shape. The 

 smallest of these bodies are kindred to those formations of the 

 gray substance considered as nuclei. Many of them are doubt- 

 ful in their nature f. i., the " cells of Deiters," which by some 

 observers are considered as nervous, by others as connective- 

 tissue, corpuscles. The larger ganglionic bodies exhibit a dis- 

 tinct angular or fusiform shape, and give rise to nerve-fibers, 

 therefore are real nerve-centers. The largest ganglionic elements 

 are found in the lateral portion of the anterior or motor horn of 

 the spinal cord. 



In the spinal cord, the groups of ganglionic elements are dis- 



Cc 



/sc 



FIG. 119. SPINAL CORD OF FROG. TRANSVERSE SECTION. 



A F, anterior longitudinal fissure ; PF, posterior longitudinal fissure ; W, white substance ; 

 A C, anterior commissure of the gray substance ; MO, anterior or motor horn of the gray col- 

 umn, rich with ganglionic elements ; SC, posterior or sensitive horn ; CO, central canal ; PC, 

 commissure layer, with fibers of the posterior commissure ; MR, anterior or motor roots; PR, 

 posterior or sensitive roots of nerves; MN, intervertebral ganglion, the connection with PR 

 broken ; V, pia mater, holding a blood-vessel. Magnified 50 diameters. 



tributed in the following way : In the anterior horn we notice 

 three groups of ganglionic elements, not distinctly marked 

 throughout the whole ; the largest group lies in the lateral por- 

 tion ; a smaller group in the anterior portion, near the greatest 

 protrusion of the anterior horn, and a third group, the smallest. 



