THE RAMUS LATERALIS ACCESSORIUS. 249 



It is possible that in the case of both of the lateral line 

 nerves the relation to the spinals is purely accidental and 

 due to the fact that the paths of the nerves in question 

 cross in the inter-muscular septa. This seems especially- 

 probable in the case of the n. lateralis vagi from its course 

 in the septum between the dorsal and ventral musculature 

 and from the loose and variable nature of the anastomosis. 

 The relation of the r. lateralis accessorius in the septum 

 between the dorsal musculature and the interspinal 

 muscles is similar. Nevertheless the remarkable con- 

 stancy of these anastomoses, especially in the latter case, 

 lends credence to the belief that they have a morphological 

 and a physiological basis. Stannius was certainly correct 

 (p. 151) in rejecting the morphological equivalency of the 

 dorsal series of anastomoses related with the r. lateralis 

 accessorius and those of the ventral rami with the sympa- 

 thetic chain. Nevertheless they may have certain physio- 

 logical features in common which will justify a comparison. 



All of the viscera of the trunk and head seem to be 

 intimately related to each other and to the central nervous 

 system through the mediation of the sympathetic nervous 

 system. Now the communis system, as we have used 

 that term, contains in addition to fibres for terminal buds 

 other sensory fibres which we have termed visceral. What 

 may be the relation (if any) between these visceral fibres 

 and those of the sympathetic cannot perhaps be determined 

 at present; but, like the sympathetic, they are known to 

 have a wide distribution to exposed visceral surfaces, and 

 I think also to the internal parts as well. In short, they 

 participate in the general sub-cutaneous and internal 

 plexus which enables the body to react as a physiological 

 unit. The enormous physiological significance of this 

 universal plexus is coming to be better appreciated than 



