Moving up one step higher, we find that the cerebellum is the organ of equilibrium, and that it as well as the spinal cord operates independently of the conscious will, for no conscious effort of the will is required to make one reel from dizziness.

As to the divisions of the greater brain or cerebrum, we want you to note that the lower brain serves a double purpose.  First, it is the channel through which pass through lines of communication to and from the upper brain and the mid-brain on the one hand and the rest of the body on the other.  Secondly, it is itself a central office for the maintenance of certain vital functions, such as lung-breathing, heart-beating, saliva-secreting, swallowing, etc., all involuntary and unconscious in the sense that consciousness is not necessary to their performance.

The next higher division, or mid-brain, is a large region from which the conscious will issues its edicts regulating all voluntary bodily movements.  It is also the seat of certain special senses, such as sight.

Lastly, the surface brain, known as the cortex, is the interpretative and reflective center, the abode of memory, intellect and will.

[Sidenote:  Drunkenness and Brain Efficiency]

The functions of these various parts are well illustrated by the effects of alcohol upon the mind.  If a man takes too much alcohol, its first apparent effect will be to paralyze the higher or cortical center.  This leaves the mid-brain without the check-rein of a reflective intellect, and the man will be senselessly hilarious or quarrelsome, jolly or dejected, pugnacious or tearful, and would be ordinarily described as “drunk.”  If in spite of this he keeps on drinking, the mid-brain soon becomes deadened and ceases to respond, and the cerebellum, the organ of equilibrium, also becomes paralyzed.  All voluntary bodily activities must then cease, and he rolls under the table, helpless and “dead” drunk, or in language that is even more graphically appreciative of the physiological effects of alcohol, “paralyzed.”  However, the deep-seated sympathetic system is still alive.  No assault has yet been made upon the vital organs of the body; the heart continues to beat and the lungs to breathe.  But suppose that some playful comrade pours still more liquor down the victim’s throat.  The medulla, or lower brain, then becomes paralyzed, the vital organs cease to act and the man is no longer “dead” drunk.  He has become a sacrifice to Bacchus.  He is literally and actually dead.

It seems, then, that the surface brain and mid-brain constitute together the organ of consciousness and will.  Consciousness and will disappear with the deadening or paralysis of these two organs.

[Sidenote:  Secondary Brains]

Yet these two organs constitute but a small proportion of the entire mass of brain and nervous tissue of the body.  In addition to these, there are not only the lower brain and the spinal cord and the countless ramifications of motor and sensory nerves throughout the body, but there are also separate nerve-centers or ganglia in every one of the visceral organs of the body.  These ganglia have the power to maintain movements in their respective organs. They may in fact be looked upon as little brains developing nerve force and communicating it to the organs.