36 ON THE NERVOUS SYSTEM IV. 



Vogt describes the glosso-pliaryngeal as giving a branch to the facial, "after 

 which it runs downwards, sends a branch to the region of the glottis, and branches 

 to the tongue as far as the tip " ; the branch to the glottis I have npt seen ; and 

 as he describes in addition a " recurrent branch," he evidently does not refer to 



this last. 



Wat^ner leaves us to infer that he finds a part of the accessory nerve of the 

 vao-us, when he says, " Some of the roots of the accessory nerve appear to be 



absent." 



Muller, quoting Weber, says : " In Frogs a branch from the ganglion of the 

 vao'us goes to the muscles of the lower jaw. It is the jugular branch of Volkman, 

 who has shown its motor influence to be derived from a branch of the facial nerve 

 which has coalesced with it. It is distributed partly to the hyoid muscles and 

 partly to the muscles of the lower jaw." * I have seen no other nerve to which 

 this description is applicable, than that formed by the union of a branch from the 

 vagus and the trigeminus ; the latter branch, arising from the side of the acoustic 

 nerve, joins the ganglion of the trigeminus, and afterAvard the branch from the 

 vagus. According to my dissections, none of its branches are muscular ; although 

 they pass among the muscles of the jaw, they were not traced to them, nor do they 

 cause them to contract when galvanized ; a small filament is given off" behind the 

 tympanum, which I at first thought was distributed to the masseter, bv;t afterwards 

 felt satisfied that I could trace it wholly to the membranous walls of the tympanic 

 cavity. Volkman's statement, that it is distributed partly to the hyoid muscles, is 

 also rendered improbable by the positive demonstration that these muscles get their 

 nervous filaments from the hypoglossus. 



Nerviis Lateralis. (Plate II. Fig. 9.) — There exists in Fishes, as has long 

 been familiarly known to comparative anatomists, a peculiar nerve, usually a branch 

 of the vagus, though it may sometimes be the result of the union of branches 

 from the vagus and trigeminus ; or it may be derived from the trigeminus alone, 

 which, from extending along the side of the body beneath the lateral line, has 

 received the name of lateral nerve. " In Salmo, Clupea, and Acipenser it is formed 

 exclusively by the vagus, but in many Fishes, as Belone, Cottus, Cyprinus, it is 

 formed by a branch of the vagus which receives branches from the trigeminus." f 

 In addition to this, there exists a nerve, first described by Weber, called the 

 dorsal nerve, formed generally by a union of filaments from the fifth and vagus, 

 which, escaping by an especial opening in the parietal and interparietal bones, 

 extends along the whole length of the dorsal fin, receiving filaments from the inter- 

 costals, and giving nerves to the muscles of the fin rays. In Silurus it is derived 

 from the fifth only, and in some others from the vagus. J The use of either of these 

 nerves is unknown ; Muller failed to produce muscular contractions by irritating 

 with galvanism the lateral nerve of the carp. It is then in all probability simply 

 a sensitive nerve. 



* Physiol., Vol. I. p. 838. 



+ Owen, Lects. on Comp. Anat., Vol. II. p. 196. 



f See Cuvier, Le^ns d'Anat. Comp., Tom. III. p. 212. 



