196 STRONG. [Vol. X. 



This involves questions hardly settled, as to change of function 

 of nerves, the innervation of the buds being taken up second- 

 arily in this case by sensory visceral nerves. 



{c) We may regard, with Mayser, the lobus vagi and tri- 

 gemini as equivalent structures, in which case there is no diffi- 

 culty presented by the innervation of the buds by various 

 nerves from these two structures. This ignores, however, 

 the greatly different innervation territory, which the lobus 

 vagi has, in other respects, as compared with the lobus 

 trigemini. 



A modification of the latter view seems most probable. The 

 lobus vagi and lobus trigemini cannot be regarded as entirely 

 equivalent structures, but the latter may be considered as 

 devoted to the innervation of the end buds, and the former 

 may be considered to contain similar fibres, in addition, how- 

 ever, to others of a different nature. We have already seen 

 (p. 189) that Mayser distinguishes two sets of fibres, medullated 

 and non-medullated, in the lobus vagi and have also found in 

 the tadpole, in such branches as the R. palatinus VII and R. 

 mandibularis internus VII, two sets of fibres, one somewhat 

 coarser and with a sheath staining much more darkly than the 

 other. This may partly account for the diminishing of the 

 lobus vagi, where the branchial cavities — which are supplied 

 with these buds in fishes — disappear. 



One fact is very apparent, both from the investigation of the 

 Amphibia and the comparison with the results of other workers 

 upon the fishes, namely, that there is no direct genetic connec- 

 tion between the lateral line system and its nerves and the 

 sense of taste and its nerve supply. The suggestion of Beard 

 upon this subject has already been criticised in my preliminary 

 communication in the Anatomischer Anzeiger (62). Both may 

 have been derived from a more generalized and older form of 

 sense organ, the end bud, present generally on the body and in 

 the mouth. The lateral-line system, whatever its origin, is a 

 specialized system, and its nerves are in every way sharply 

 contrasted with those connected with taste. The auditory 

 organ is the only one whose connection with the lateral-line 

 system is at all probable. 



