66 NERVE COMPONENTS OF BONY FISHES. 



Strand of viscero-motor cells of the spinal cord running 

 along the lateral and ventro-lateral side of the canalis cen- 

 tralis, the paracentral nucleus of Onuf and Collins. 



Fiirbringer ('97, pp. 664 and 680) assigns to these para- 

 central cells (his ventro-lateral series) and their fibres 

 which emerge with the dorsal roots (his lateral fibres) the 

 viscero-motor function throughout the Vertebrata, includ- 

 ing the Cyclostomata and Amphioxus. The visceral 

 component is larger in cyclostomes than in higher verte- 

 brates. These cells he also directly compares with the 

 viscero-motor nuclei of the oblongata. 



V. — Summary of Section 3. 



The general cutaneous nerves enter the brain by the V 

 and X roots. The trigeminal fibres terminate in part in 

 a chief trigeminal nucleus mesally of the point of entrance 

 of the root, while the larger part pass caudad as the spinal 

 V tract to terminate, after receiving the general cutaneous 

 component of the vagus, in the n. funiculi of the spinal 

 cord. This system is, therefore, the direct cranial repre- 

 sentative of the dorsal cornu of the cord. 



All nerves of the acustico-lateral system (r. lateralis 

 vagi, VIII, dorsal and ventral lateralis roots of VII) ter- 

 minate in the tuberculum acusticum, which is intimately 

 related to the cerebellum. This system has also ascend- 

 ing (cerebellar) and descending (spinal VIII) roots. 



The communis system is represented in the VII, IX 

 and X nerves. The terminal nucleus for all of its fibres 

 lies in the lobus vagi. This system is very completely 

 isolated and unified in the head, and yet is apparently 

 related to a sensory system of the trunk, closely associated 

 with the spinal viscero-motor centres (intermediate zone). 

 The communis system was primarily a viscero-sensory 



