116 JOURNAL OF COMPARATIVE NEUROLOGY. 
fibres (Fig. 18, a) have some half-dozen principal branches of 
various lengths, none of them very long nor diverging widely 
from the main stem; besides the principal branches, there are 
shorter twigs distributed sparingly along both the main stem 
and its ramifications. Other fibres (Fig. 18, c) are so beset with 
a multitude of small twigs, quite irregular in their branching, 
that the whole series is given much the appearance of a long 
and cylindrical brush. Between these two extremes, there are 
every intermediate condition of branching forms. 
The ependymal fibres lie quite near to each other, and the 
many processes from them constitute an interlacing tangle, the 
profusion and extreme delicacy of which cannot be adequately 
represented in any drawing. In order to appreciate the. signifi- 
cance of this dense supporting framework, the vast number of 
the granular neurones must be recalled. Here we find the 
means by which these nervous elements are given that support 
which is one of the primary conditions for their activity. 
b. Neurogta.—The neuroglia provides a support for the 
outer structures of a cerebeliar fold, just as the ependyma func- 
tions within. The characteristics of neurogliar elements are 
shown in Fig. 19, as¢. and dg. f. The cell-body lies at the junc- ° 
ture of the molecular and granular layers, between the cells of 
PuRKINJE. Two conditions are to be distinguished. One vari- 
ety (Fig. 19, ast.) hasa cell-body of quite irregular outline 
from which many processes radiate. These processes rarely 
branch. Some of them may proceed toa distance equal to 
several times the greater axis of the cell, but most of the 
branches are far shorter. They are placed so closely along the 
margin of the cell that the whole has something the effect of a 
halo. These cells are clearly homologous with the astrocytes 
of higher vertebrates. 
The other type of neuroglia-cell (Fig. 19, dg. f.) is refer- 
able to the category of BERGMANN’s fibres of the mammalian 
cerebellum. The cell-body has fewer processes than the astro- 
cyte, but it gives origin to one stout fibre which takes a periph- 
eral course, without branching, through the entire thickness of 
the molecular layer. The path of the fibre is not one directly 
5 seal Pe a ee oe ee 
