emoved, 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
upward and forward until they are blended with the tubercles of the
_corpora quadrigemina_. The second are the _crura cerebelli_, which
unite in two large _fasciculi_, or pyramids, and are finally lost in the
_pons varolii_. The inferior peduncles are the corpora restiformia,
previously described, and consist of both sensory and motor filaments.
Some physiologists suppose that the cerebellum is the source of that
harmony or associative power which co-ordinates all voluntary movements,
and effects that delicate adjustment of cause to effect, displayed in
muscular action. This fact may be proved by removing the cerebellum of a
bird and observing the results, which are an uncertainty in all its
movements, and difficulty in standing, walking, or flying, the bird
being unable to direct its course. In the animal kingdom we find an
apparent correspondence between the size of the cerebellum and the
variety and extent of the movements of the animal. Instances are cited,
however, in which no such proportion exists, and so the matter is open
to controversy. The general function of the cerebellum, therefore,
cannot be explained, but the