g6 Bulletin of Laboratories of Denison University [Voi. xiii 



by a broad dorsal commissure, above which is a commissure of 

 the acustico-laterahs centers lying under the lateral extensions 

 of the cerebellum. They are enveloped on all sides by tracts 

 of fibers running vertically between the cerebellum and the re- 

 gions in the brain stem below and cephalad of the nuclei, the 

 cerebellar tracts forming a sort of capsule around the grey nu- 

 clei, these relations being the same as already described for 

 cyprinoids. The relations of this nucleus and its tracts are 

 shown in Fig. 37. 



The intrinsic neurones of these nuclei are rarely well im- 

 pregnated in my Golgi preparations. The fibers of the cen- 

 tral gustatory path end for the most part in free arborizations 

 among these cells without crossing. But some of the tract 

 fibers are clearly seen to cross to the opposite nucleus through 

 the commissure of the secondary gustatory nuclei, as Mayser 

 has stated. 



The tertiary tract arises from the chief cells in the cortical 

 portions of the nucleus. These are frequently impregnated 



Fig. J7. A parasagittal section taken through the brain of Amciiirus nebu- 

 losus so cut as to pass through about the middle of one vagal and one facial lobe 

 and the lateral part of the cerebellum (cf. Figs. 5 and 20). Drawn from a single 

 GoLGi preparation. X 45- 



The section shows nearly the whole course of the central gustatory path 

 {sec. gust. t.), composed of neurites of the chief secondary gustatory neurones of 

 the vagal and facial lobes which terminate in the secondary gustatory nucleus 

 (s.g.ii.) under the cerebellum. The origin of the facial portion of the descend- 

 ing secondary gustatory tract {desc.sec. VII.) is seen in the facial lobe. In the 

 facial lobe there is also seen a portion of the lateral part of the communis root of 

 the facial nerve {com, VII) passing up to arborize within the lobe. The neurones 

 of the vagal and facial lobes, which were richly impregnated in the preparation, 

 are omitted from the drawing for the sake of simplicity. Along the cephalic 

 border of the secondary gustatory nucleus is the beginning of the secondary gus- 

 tatory commissure {s.g.c.\. The origin of the tertiary gustatory tract from the 

 secondary nucleus is not shown, but the terminations of these fibers {gust.j) are 

 illustrated in the inferibr lobe. 



Bundles of fibers from the tuberculum acusticum are seen under the facial 

 lobe, where they decussate, and their termini in the nucleus lateralis mesenceph- 

 ali (torus semicircularis or colliculus) are also shown {sec.VIII). Under the cer- 

 ebellum are the cerebellar tracts which envelop the secondary gustatory nucleus 

 (r). Granules of the cerebellum are marked gr.; those of the valvula, ^. The 

 bodies of the Purkinje Cells of the cerebellum are indicated by dotted outlines. 

 7iuc.com,,, is the commissural nucleus of C.\j.\L. 



