known
by the fanciful name of _arbor vitae_ (see fig. 6). Independent masses
of grey matter are, however, found in the interior of the cerebellum.
If the hemisphere be cut through a little to the outer side of the
median lobe, a zigzag arrangement of grey matter, similar in
appearance and structure to the nucleus of the olivary body in the
medulla oblongata, and known as the _corpus dentatum_ of the
cerebellum, is seen; it lies in the midst of the white core of the
hemisphere, and encloses white fibres, which leave the interior of the
corpus at its inner and lower side. On the mesial side of this _corpus
dentatum_ lie three smaller nuclei. The white matter is more abundant
in the hemispheres than in the median lobe, and is for the most part
directly continuous with the fibres of the peduncles of the
cerebellum. Thus the restiform or inferior peduncles pass from below
upward through the white core, to end in the grey matter of the
tentorial surface of the cerebellum, more especially in that of the
central lobe; on their way they are connected with the grey matter of
the corpus dentatum. The superior peduncles, which descend from the
corpora quadrigemina of the cerebrum, form connexions mainly with the
corpus dentatum. The middle peduncles form a large proportion of the
white core, and their fibres terminate in the grey matter of the
foliated cortex of the hemispheres. It has been noticed that those
fibres which are lowest in the pons go to the upper surface of the
cerebellum and vice versa.

_Histology of the Cerebellum._--The white centre of the cerebellum is
composed of numbers of medullated nerve fibres coursing to and from
the grey matter of the cortex. These fibres are supported in a
groundwork of neuroglial tissue, their nutrition being supplied by a
small number of blood vessels.

[Illustration: From Cunningham, _Text-book of Anatomy_.

FIG. 7.--Transverse Section through a Cerebellar Folium (after
Kolliker). Treated by the Golgi method.

P. Axon of cell of Purkinje.
F. Moss fibres.
K and K^1. Fibres from white core of folium ending in molecular
layer in connexion with the dendrites of the cells of Purkinje.
M. Small cell of the molecular layer
GR. Granule cell.
GR^1. Axons of granule cells in molecular layer cut transversely.
M^1. Basket-cells.
ZK. Basket-work around the cells of Purkinje.
GL. Neuroglia