PHYSICAL ANTECEDENTS OF SCIENCE 115

part of each lateral half of the spinal cord, are mixed and

run together into the nerves or rather compose them

but those connected with its anterior half go especially to

the muscles, while those from its posterior half go especially

to the skin.

Within the spinal cord itself is a mass of longitudinal

nervous fibres and more or less spherical nervous "cells."

The fibres extend upwards and downwards, towards and

from the brain, and are closely connected with the spinal

nerves.

The brain (which is entirely enclosed within the skull, and

is composed of delicate nervous filaments and a multitude of

cells) is the expanded summit of the whole nervous axis, and

may be said to consist of three noticeable portions : (i) The

hindmost under part, or medulla, which may be described as

the expanded upper part of the spinal cord, so becoming the

posterior portion of the base of the brain. (2) The cerebellum,

a rounder, narrowly grooved prominence, forming the posterior

under portion of the brain. (3) The third part, which is by

far the largest, is formed in part by the continuance forwards

and the divergence of the nervous axis, in part by connexion

with the cerebellum, and also by a very large quantity of

nervous tissue apparently independent of either. This whole

mass, called the cerebrum, is divided by a deep, median

groove into two lateral halves the cerebral hemispheres

which form the whole of the upper surface of the brain,

and are marked all over by meandering rounded prominences

the convolutions of the brain. The cerebral hemispheres

are deemed to be main agents in occasioning our sensations

and imaginations, and it is very noteworthy that as we have

two eyes and two ears, so also we have two distinct yet

similar cerebral organs which are of such importance. The

greater number of the nerves which proceed from the brain

have their origin in the medulla. This is notably the case

part of each lateral half of the spinal cord, are mixed and

run together into the nerves or rather compose them

but those connected with its anterior half go especially to

the muscles, while those from its posterior half go especially

to the skin.

Within the spinal cord itself is a mass of longitudinal

nervous fibres and more or less spherical nervous "cells."

The fibres extend upwards and downwards, towards and

from the brain, and are closely connected with the spinal

nerves.

The brain (which is entirely enclosed within the skull, and

is composed of delicate nervous filaments and a multitude of

cells) is the expanded summit of the whole nervous axis, and

may be said to consist of three noticeable portions : (i) The

hindmost under part, or medulla, which may be described as

the expanded upper part of the spinal cord, so becoming the

posterior portion of the base of the brain. (2) The cerebellum,

a rounder, narrowly grooved prominence, forming the posterior

under portion of the brain. (3) The third part, which is by

far the largest, is formed in part by the continuance forwards

and the divergence of the nervous axis, in part by connexion

with the cerebellum, and also by a very large quantity of

nervous tissue apparently independent of either. This whole

mass, called the cerebrum, is divided by a deep, median

groove into two lateral halves the cerebral hemispheres

which form the whole of the upper surface of the brain,

and are marked all over by meandering rounded prominences

the convolutions of the brain. The cerebral hemispheres

are deemed to be main agents in occasioning our sensations

and imaginations, and it is very noteworthy that as we have

two eyes and two ears, so also we have two distinct yet

similar cerebral organs which are of such importance. The

greater number of the nerves which proceed from the brain

have their origin in the medulla. This is notably the case