140 ME. P. J. COLE OX THE STEUCTUEE AND MOEPHOLOGY OF 



them) lying in the root of the palatine trunk." In my Chhncera paper I was inclined to 

 doubt the separate existence of the palatine cells described by Ewart, and considered 

 them part of the geniculate ganglion — in which is seen the evil of basing general con- 

 clusions on a special study. It is now obvious to me that these cells form a perfectly 

 distinct prsB-branchial ganglion, comparable to the facial ganglion of the Codfish. We 

 have seen that BonsdorfF compared the latter to the otic ganglion, and Ewart now 

 compares it to the spheno-palatine ganglion. Both conclusions are erroneous, although 

 both come somewhat near the truth. There is less objection to the splieno-palatine than 

 to the otic ganglion, since the former is apparently more distinctively connected with the 

 facial nerve than tlie latter. Both ganglia are essentially vagrant and largely motor, 

 and hence cannot correspond either to the facial ganglion of the Cod or Evvart's palatine 

 cells in Elasmobranchs. But Dixon's work (6i) conclusively settles the matter. He 

 shows that both ganglia are developed in connection with brandies of the trigeminal 

 nerve, and only become secondarily connected late in development with the facial. They 

 cannot therefore correspond to a ganglion belonging essentially to the facialis. Before 

 leaving Ewart's work I should like to quote a passage on p. 3 which has some bearings 

 on the jDresent issue. He says : — " In the skate there is but a single ganglionic swelling 

 on the root of the glossopharyngeal, but this swelling contains two kinds of cells. The 

 dorsal part from which the dorsal branch springs consists of large cells, loMle the deeper 

 part, from which the fibres of the pharyngeal branch proceed, consists of small cells'' 

 (Italics mine.) 



The important work piil)lished by Strong (1895, 204) helps us very considerably in 

 clearing up the morphology of the facial ganglion of the Cod. In all Eishes and Amphi- 

 bians there is an important system of fil)res entering into the composition of the Vllth, 

 IXth, and Xth cranial nerves, to which Osboi-n (147) devoted considerable attention, and 

 which was called by him the fasciculus conimunis system. These fibres were carefully 

 investigated and grouped by Strong, who showed (1) that they had a distinctive origin in 

 the brain; (2) that they formed- the palatine or visceral and prm-branchial (=^Ghorda 

 tympani in- case of facial) divisions of the branchial nerves; and (3) that they were gan- 

 glionated. It hence follows (1) that the prae-branchial ganglia described by Shore and Ewart 

 are simply the ganglia on the fasciculus communis fibres; and (2) that the prce-branchial 

 fibres have a different internal origin in the brain than the post-branchial fibres. As to 

 the nature of the fasciculus communis tract, Strong says (p. 182) that it is " composed 

 exclusively, or almost exclusively, of visceral (splanchnic) fibres innervating the ali- 

 mentary canal and its appendages " (italics mine), and considers that it is " mainly sensory '' 

 in function. Other important conclusions arrived at by Strong, after careful investi- 

 gation and consideration of the literature, are (1) that the fasciculios communis corresponds 

 ioith the mammalian fasciculus solitarius in every detail ; (2) that " as the fasciculus soli- 

 tarius is continued cej)halad into the portio intermedia, it is evident that the portio intern- 

 media is represented ui the tadpole by the fasciculus communis root of the Vllth, the 

 ganglion geniculi by the ganglion of this root, fused in the tadpole with the ganglion Gasseri. 

 l)ut separate in Amblystoma, and the chorda tympani by the portion of the fasciculus 



