250 NERVIi COMPONENTS OF BONY FISHES. 



formerly; and it has a morphological value which is not 

 as yet fully recognized. The fibres of this plexus will 

 tend to gather about and distribute with the larger nerve 

 trunks of whatever type simply because these afford the 

 paths of least resistance; and if two nerves cross, even 

 though they be of unlike composition and do not exchange 

 fibres with each other, yet this will form a nodal point in 

 this plexus of visceral fibres. This factor will operate to 

 draw contiguous nerves together, even though they may 

 be of totally dissimilar composition, and may account for 

 the tendency, everywhere noticeable, for nerves of the 

 several components to accompany each other, often com- 

 ing from widely separated origins and deviating from 

 their natural courses to do so. 



The ramus lateralis accessorius originates in Menidia in 

 an elaborate plexus of communis fibres, arising partly 

 from the facial nerve and partly from the vagus complex. 

 This plexus is exceedingly rich and intricate in the men- 

 inges and under the skin of the dorsal part of the head 

 and trunk, only the main nerves being indicated on the 

 plots. This nerve was, doubtless, primarily visceral in its 

 proximal portions at least, while in that portion which 

 leaves the head to enter the trunk I incline to the belief 

 that the terminal bud fibres appeared first. But be that 

 as it may, the visceral fibres followed and when the r. 

 lateralis accessorius crossed the dorsal rami of the spinal 

 nerves, connections of their visceral fibres were secondarily 

 effected. In cases where the r. lateralis accessorius sends 

 a ventral branch to the anal fin, as in Gadus, that branch 

 effects similar connections with the ventral rami of the 

 spinal nerves. 



The r. lateralis vagi may effect similar quite secondary 

 connections with the r. medius of the spinal nerves; but> 



