s of any faculty,
unless corresponding parts were destroyed in each hemisphere.

The left brain governs the right half of the body, and the right brain
governs the left half, the connecting fibres having their crossing
(called decussation) in the spinal cord. Hence the left brain is
usually more fully developed in the occipital and basilar regions than
the right, in right handed people, as may frequently be detected by a
careful examination of the head, or an inspection of the interior the
skull. The left brain, also, seems to have a general ascendency over
the right; so that paralysis of speech is most generally produced by
disease in the region of language on the left side.

Whatever occurs on one side of the body is in relation to the opposite
side of the head. Paralysis, if not dependent on the spinal cord, is
dependent on the basilar region of the opposite side of they brain;
and conditions of the right eye affect the lower margin of the left
front lobe, in which the perceptive organs are situated.

If we thrust our fingers into the brain immediately under the corpus
callosum, pushing away the delicate little structure called the
_septum lucidum_ (or translucent septum), and pressing down fornix
(which is a thin, horizontal nerve membrane) we find that our fingers
enter a cavity by pressing its walls apart, of which the corpus
callosum is the vault or roof,--a cavity which may be explored back
and forth, far into the interior of the occipital lobe within an inch
of the surface, and far into the front lobe, near the surface of the
frontal convolutions, as well as downwards and forwards into the
bottom of the middle lobe (the part called temporo-sphenoidal). These
extensions of this great cavity or ventricle are called the anterior
and posterior horns (_cornua_) and the descending horn (_cornu_).

Their importance arises from the fact that in these ventricles of the
right and left sides of the brain a watery fluid, effused from the
blood, called serum, exists, which also extends downward along the
spinal cord, and which has to do with the pressure and equilibrium of
the various parts. When there is a strong pressure of blood to the
brain on account of its unusual activity, especially in the activity
of the emotions, the serum of the ventricles and also in the substance
of the brain is absorbed, and the brain acquires a more compact
texture, which is found in all persons of strong mentality, the brain
being harden