CHAPTER XV. 



NERVOUS SYSTEM. 



Superior cervical ganglion. Man. (p. 3, s. 22 & 24, c. P., 

 m. B.) (L.) and (H.) Superficially a thin laminated perineurial 

 sheath internally nerve cells of various sizes, and many contain 

 crescentic patches of pigment granules. Each cell has a 

 nucleated capsule. There is much tissue between the cells 

 consisting of non-medullated nerve fibres and filaments and 

 capillaries. The entering nerves are of the non-medullated 

 variety for the most part. 



Posterior root ganglion. Man. (p. 3 or 11, s. 22 & 24, 

 c. P., m. B.) (L.) and (H.) The structure is fusiform, and there 

 is an entering and an emerging mass of medullated nerve fibres, 

 The perineurial sheath is well marked. The cells are somewhat 

 larger than in the sympathetic and of a more uniform size ; 

 their capsules are distinct, but there is less intervening tissue. 



Vagus Nerve, Man or Dog, T.S. of. In the neck. (p. Osmic 

 acid, c. P., m. B.) The perineurial coat is strong around the sub- 

 divisions of the nerve. Sketch the structure, and pay special 

 attention to the size of the nerves in the fibres in different 

 localities. Compare with the sciatic nerve examined earlier on. 



Spinal Cord. 



Cord of rabbit. T.S. upper thoracic region, (p. 3., s. aqueous 

 methylene blue in bulk, c. P., m. B.) 



Cord, Man, Thoracic region (p. 11, s. 19, c. G., m. F.) Examine 

 both of these for the following points of structure. (L) The 

 cord is closely invested by the thin fibrous pia mater. 



