108 JoURNAL OF ComPARATIVE NEuUROLOGY. 
bellum is readily followed, for in no other part of the brain are 
distinctions more clearly marked. Superficially, there is the 
molecular layer (Fig. 12, m. ¢.); the granular layer lies next to 
the ventricle, or is separated from it only by the basal fibres 
(Fig. 12, g. 2); between the two, there is the layer of PURKINJE 
(Pig, 12; 9. 7). 
The nerve-fibres of the organ are found in two well-defined 
groups, the basal fibres and the median fibres. The basal fibres 
(Fig. 12, 6. f.) enter the posterior region from the oblongata 
and soon become dissolved in the outer layers. These fibres 
lie next to the ventricle, and they supplant the granular layer 
entirely during their course, or at least displace it quite largely. 
The median fibres are disposed in scattered bundles which lie 
in the outer part of the granular layer just beneath the cells of 
PurkINJE. The bundles take two general directions: trans- 
verse, (cut across in Fig. 12, #. f/’.); and longitudinal, entend- 
ing parallel with the structural zones (Fig. 12, m. f.). 
I. The Neurones of Purkinge. 
The neurones of PuRKINJE are the largest, and by far the 
most impressive structural elements of the cerebellum. Their 
cell-bodies are disposed in a thin stratum intercalated between 
the molecular and the granular layers. At those points where 
the granular layer is absent, the PURKINJE cells come into direct 
contact with the layer of basal nerve-fibres, instead. As to 
superficial distribution, the neurones follow a well-defined rule 
(Fig. 12, ~. 7.). They are most numerous on the side of a 
cerebellar fold, often several cells in depth here, and not infre- 
quently having their cell-bodies in contact. At the summit of 
the fold, there are wider spaces between the individual cells; 
and for a small space at the bottom of a fold, the cells are ab- 
sent altogether. The posterior fold of the cerebellum has a part 
of its area without PURKINJE neurones. 
Fig. 13 illustrates the features of external morphology 
characteristic of a neurone of Purkinyz. The cell-body is sit- 
uated, as already noted, at the base of the molecular layer. The 
dendrites, therefore, grow upward into the molecular layer, and 
Pa ee a ee 
