t portion of the brain is believed to be the region that is most
important in governing the intelligence. The central and posterior
portions of the cerebrum contain the centers for the voluntary motions
of the face and of the front and hind legs. The growth of a tumor or an
inflammatory change in the region of a center governing the motion of a
certain part of the body has the effect of disturbing motion in that
part by causing excessive contraction known as cramps, or inability of
the muscles to contract, constituting the condition known as paralysis.
The nerve paths from the cerebrum, and hence from these centers to the
spinal cord and thence to the muscles, pass beneath the small brain, or
the cerebellum, and through the medulla oblongata to the spinal cord.
Interference with these paths has the effect of disturbing motion of the
parts reached by them. If all of the paths on one side are interfered
with, the result is paralysis of one side of the body.

The small brain, or cerebellum, governs the regularity, or coordination,
of movements. Disturbances of the cerebellum cause a tottering,
uncertain gait. In the medulla oblongata, which lies between the spinal
cord and the cerebellum, are the centers governing the circulation and
breathing.

The spinal cord carries sensory messages to the brain and motor
impressions from the brain. The anterior portions of the cord contain
the motor paths, and the posterior portions of the cord contain the
sensory paths.

Paralysis of a single member or a single group of muscles is known as
monoplegia and results from injury to the motor center or to a nerve
trunk leading to the part that is involved. Paralysis of one-half of the
body is known as hemiplegia and results from destruction or severe
disturbances of the cerebral hemisphere of the opposite side of the body
or from interference with nerve paths between the cerebellum, or small
brain, and the spinal cord. Paralysis of the posterior half of the body
is known as paraplegia and results from derangement of the spinal cord.
If the cord is pressed upon, cut, or injured, messages can not be
transmitted beyond that point, and so the posterior part becomes
paralyzed. This is seen when the back is fractured.

Abnormal mental excitement may be due to congestion of the brain or to
inflammation. The animal so afflicted becomes vicious, pays no attention
to commands, cries, runs about in a circle, stamps with the feet,
strikes, kicks, e