2IO NERVOUS SYSTEM OF VERTEBRATES. 



any connection with the sympathetic cells. The fibers are 

 finally distributed by widespread branches to the mucosa of the 

 viscera. Some of these fibers also enter the Pacinian corpuscles 

 as the fibers of those sense organs. The distribution of these 

 fibers and their lack of histological connection with the sympa- 

 thetic ganglia show that they do not belong properly to the sympa- 

 thetic system. The truth is rather that they are older than the 



intm.Z. 

 Intm.Z 



pare; 



Fig. 109. — Diagram illustrating the spinal representation of the sympathetic 

 nerves in a mammal. From Onuf and Collins. CI. Clarke's column; intm. Z., 

 intermediate zone; Bechl. N., Bechterew's nucleus; lat., lateral horn cell-group; 

 pare, paracentral cell -group. 



sympathetic system and that the sympathetic ganglia are placed 

 along the course of these primitive visceral sensory fibers. Cen- 

 trally, these fibers enter the visceral sensory column of the cord 

 or brain as already described. 



(2) Eft"erent fibers whose cells of origin are in the spinal cord 

 or brain. The location of the cells of origin of these fibers has been 

 determined with accuracy in the spinal cord of the cat. As indi- 



