6 'Journal of Comparative Neurology and Psychology. 



by communis fibers, we may confine our attention to this com- 

 ponent. As mentioned above, all communis fibers end in a mor- 

 phologically single center, those from the ninth and tenth nerves 

 in the lobus vagi and those from the VII nerve in the lobus facialis, 

 which correspond in the position in the medulla to the visceral 

 sensory or region of Clarke's column in the cord. All communis 

 fibers running out through the VII nerve trunk and through what 

 are commonly designated as the fifth rami come from the genicu- 

 late ganglion of the VII nerve, while those running out through 

 the ninth and tenth nerves come from ganglia situated on those 

 nerves. The communis fibers coming from the geniculate gan- 

 glion enter the brain anterior to the position of their nucleus and 

 pass back as the fasciculas communis or fasciculus solitarius of 

 mammals to the facial lobe. 



The communis component consists of unspecialized fibers sup- 

 plying mucous surfaces and specialized fibers supplying taste 

 buds situated in both ectoderm and endoderm. These specialized 

 and unspecialized divisions cannot be accurately separated cen- 

 trally although Herrick ('05) has w^orked out the reflex gusta- 

 tory paths both ascending and descending in the cyprinoids and 

 siluroids. This is the first successful attempt to trace definitely 

 the secondary and tertiary gustatory paths in any vertebrate, and 

 from being the least known system centrally, the communis sys- 

 tem, at least in teleosts, is one of the best defined systems both 

 peripherally and centrally of any of those contained in the cranial 

 nerves. 



The communis fibers running out through the IX and X nerves 

 are fairly constant in their distribution. The IX nerve may send 

 fibers to the surface of the body, as in Menidia, but the distribu- 

 tion seems usually to be confined to mucous surfaces as in 

 Ameiurus. The communis fibers arising from the geniculate 

 ganglion, however, show the greatest diversity in the number of 

 rami through which they pass to the surface and in the extent 

 and variety of the surface innervated. They may pass out through 

 only one ramus, as in Petromyzon (Johnston '05), or two as in 

 Rana (Strong '95), or three as in Amblystoma (Coghill '02) 

 and Triton (Coghill '06) and Amia (Allis '97), or five as 

 in Pleuronectes (Cole '01), Gadus (Herrick 'go), Menidia 

 (Herrick '99), or even as many as twelve rami in Ameiurus 

 (Herrick '01). 



