THE NEkVOUS SYSTEM OF MAN. g~ 



untary system may be made to illustrate this also by 

 adding battery cells all along the cable within the arch- 

 way, and these also sending out wire's to intelligence 

 offices and executive offices in every part of the country 

 and controlling all necessary routine business without 

 troubling the head center except in case of extreme 

 emergency. By some stretch of the imagination they 

 may be compared to state government. 



SECTION IV. 

 Ganglionic System. 



It will be remembered that we divided the whole 

 nervous system of vertebrates into two subsystems, 

 viz., the cerebro-spinal and the ganglionic. The latter 

 we put aside for the time. We now take it up, but very 

 briefly, because it is very imperfectly understood. 



Definition. — Nerves are cylindrical bundles of fibers. 

 Every knot or swelling on these cylindrical strings con- 

 tains gray matter with cells and gives out the two kinds 

 of fibers terminating in the tissues. In a word, they are 

 little centers of force and are called ganglia. Now the 

 ganglionic system is so called because it consists en- 

 tirely of such small ganglia scattered about in the body 

 and connected by nerve strings. 



Description. — The system consists (i) of a series of 

 ganglia on each side of the spinal column (not in the 

 canal) the whole way from the base of the skull to the 

 end of the sacrum, one opposite each joint of the col- 

 umn (see Fig. 38, gg). (2) This series of ganglia is con- 

 nected throughout on each side by a nerve cord. The 

 two knotted cords thus formed are called the sympa- 

 thetic nerves (Fig. 38, n n). (3) From each spinal nerve 

 there goes off a small branch which connects with the 

 sympathetic nerve on each side, and thus the two sys- 



