268 NERVE COMPONENTS OF BONY FISHES. \ 



r. lateralis accessorius dorsally, from which they dis- 

 tribute to the skin and adjacent muscles. The r. later- 

 alis accessorius appears to serve as a collector for these 

 nerves, though there is no evidence that any fibres pass 

 in it very far from the segment in which they are related 

 to the spinal cord. 



Viscero-motor fibres are doubtless present, here as in 

 other cases, in both the dorsal and ventral roots, though 

 my methods have not differentiated them. Such fibres 

 probably originate from the cells of the paracentral nucleus 

 {pen.) lying ventro-laterally of the canalis centralis and 

 in what might be termed the cervix of the ventral cornu. 

 There are probably also viscero-sensory connections of 

 some sort in the spinal cord, though what they are in the 

 fishes remains problematical. 



2. — The Vagus. 



The relations of the components in the vagus nerve are 

 shown in Fig. 9. The motor fibres all belong to the vis- 

 cero-motor type and come from the nucleus ambiguus and 

 the commissura accessoria of Mauthner. The latter prob- 

 ably come partly from the n. ambiguus of the opposite 

 side and partly from the fasciculus longitudinalis dorsalis. 

 They distribute to the pharyngeal muscles and to the m. 

 trapezius (n. accessorious). There are probably other 

 motor fibres of smaller calibre which distribute to the 

 unstriated visceral musculature. 



The communis root from taste buds, terminal buds and 

 general visceral surfaces terminates in the lobus vagi. It 

 makes up by far the largest part of the vagus. 



The general cutaneous root arises from the jugular 

 ganglion, which gives rise peripherally to the rami 

 cutanei dorsales vagi. Centrally its fibres terminate in 



