ntrolling and conscious brain and the corporeal organs.

The tentorium does not entirely separate it from the cerebrum, for
anteriorly it is open to permit the passage of the fibres which
connect the cerebrum with the spinal cord and the cerebellum,--fibres
which pass up midway between the right and left ear, so that a bullet
fired horizontally through from ear to ear would sever the connection
of the cerebrum with the bodily organs, producing instant death. This
will be understood by looking at the profile of the interior of the
right hemisphere, on which we see the position of the pons and the
medulla and their relation to the cerebrum by their ascending fibres.
As these ascending fibres correspond to a position just above the
cavity of the ear, and as they are the channels of all muscular
impulses, the reader will perceive that breadth of head immediately
above the cavity of the ear must be associated with muscular
impulsiveness.

The position of the cerebrum in the cranium may be best understood by
sawing the head in two horizontally, taking out the brain, and looking
down into the base of the skull, in which we see anteriorly a shelf
for the front lobes, behind which are the cavities for the middle
lobes, and behind that the rounded cavities for the cerebellum.

[Illustration]

Thus the front lobe occupies the highest plane, resting on the vault
of the sockets of the eyes, and extending back as far as the sockets.
The middle lobe lies behind the sockets of the eyes and above the
cavities of the ears, its base being as low as the bottom of the
sockets of the eyes and corresponding nearly with the upper edge of
the cheekbone, as it extends from the sockets to the side of the head
just in front of the ears. In the posterior base of the skull, the
reader will observe an opening (_foramen magnum_ or large foramen)
through which the spinal cord ascends. The spinal cord is exposed in
the neck below the foramen.

Going back, we find the middle lobe rises higher, ascending over the
cavity of the ear and resting upon the ridge of bone in which the
apparatus of hearing is situated, thus reaching the level of the
tentorium, on which the occipital lobe rests.

The bones of the cranium seen by looking down into the basis of the
skull, as above, are the frontal bone over the eyes, the sphenoid
bone, behind the sockets of the eyes, extending from the right to the
left temple, the temporal bones, forming the ridge that holds