CEREBELLUM OF URODELE AMPHIBIA 5 



Whether any of these and the few subepend5anal nuclei under 

 the cerebellar conunissure (fig. 25) are functional neurones has 

 not been determined. 



The neurones of the cerebellum of Necturus, like those of the 

 other parts of the brain, are arranged as a deep stratum griseum 

 bordering the ventricle. Both dendrites and neurites are in gen- 

 eral directed outward into the stratum album. These neurones 

 have not been exhaustively studied, but so far as observed they 

 seem like greatly simplified Purkinje neurones. No cells are im- 

 pregnated in our Golgi preparations which can be compared with 

 the granules of more highly developed cerebella. 



Some neurones of the floor of the recessus lateralis are seen in 

 figure 17. This illustrates a transverse section through the 

 lateral recess at a level between those of figures 6 and 7. The den- 

 drites of these cells are directed partly downward into the under- 

 lying tractus spino-cerebellaris and partly medialward at the 

 outer border of the stratum griseum. The former may engage 

 terminals of the tractus spino-cerebellaris and also unmedullated 

 ascending fibres from the area acustico-lateraUs. The latter 

 spread out among fascicles of coarse heavily medullated fibers 

 which pass between this portion of the cerebellum and the medial 

 raphe and may receive secondary trigemino-cerebellar fibers by 

 way of those fascicles. The neurites of these neurones can be 

 followed for only a very' short distance, probably entering the 

 tractus cerebello-tegmentalis and brachium conjunctivum. 



The collection of neurones last described is continuous forward 

 with both the medial and the lateral walls of the recessus lateralis. 

 The dorsal border of the lateral wall is very thin, containing one 

 to three layers of cells beside the ependyma. The few imperfect 

 impregnations of these cells which I have seen indicate that they 

 are greatly reduced Purkinje neurones (fig. 19). 



Figures 18 and 19 illustrate two horizontal sections taken 

 through the anterior diverticula of the lateral recesses. They 

 are from different specimens but from approximately the same 

 level, figure 18 showing the left side and figure 19 the right side. 

 The cerebellar neurones in in this region send their dendrites for- 

 ward and downward, where they engage terminals of the tractus 



