the ganglia of these parts.

The _Posterior Pyramids_ are much smaller than the other columns of the
medulla oblongata. They are situated (4, 4, Fig. 59) upon the margin of
the posterior fissures in contact with each other.

The functions of the medulla oblongata, which begin with the earliest
manifestations of life, are of an instinctive character. If the
cerebellum and cerebrum of a dove be removed, the bird will make no
effort to procure food, but if a crumb of bread be placed in its bill,
it is swallowed naturally and without any special effort. So also in
respiration the lungs continue to act after the intercostal muscles are
paralyzed; if the diaphragm loses its power, suffocation is the result,
but there is still a convulsive movement of the lungs for sometime,
indicating the continued action of the medulla oblongata.

The _Cerebellum_, or little brain, is situated in the posterior chamber
of the skull, beneath the _tentorium_, a tent-like process of the dura
mater which separates it from the cerebrum. It is convex, with a
transverse diameter of between three and one-half and four inches, and
is little more than two inches in thickness. It is divided on its upper
and lower surfaces into two lateral hemispheres, by the superior and
inferior vermiform processes, and behind by deep notches. The cerebellum
is composed of gray and white matter, the former being darker than that
of the cerebrum. From the beautiful arrangement of tissue, this organ
has been termed the _arbor vitae_.

The _peduncles of the cerebellum_, the means by which it communicates
with the other portions of the brain, are divided into three pairs,
designated as the _superior_, _middle_ and _inferior_. The first pass