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The Sensorium and the Motorium.-Self reigns in the cerebral ganglia. Here he receives messages and issues his mandates. Mind is the inner world, is self. All else, even the sensorium and motorium, is the outer world, is the not-self.

1. The sensorium is the portion of the nervous organism which conditions sensation, and in common use is limited to the cerebral hemispheres. It is here used, for the sake of brevity, to include the sensor organs, special and general, the sensor nerves, and the sensor ganglia. As sense-perception occurs only in connection with the cerebral sensor ganglia, these ganglia strictly constitute the sensorium.

2. The motorium is the portion of the nervous organism through which self sends messages to the outer world. It includes the motor ganglia, the motor nerves, and the motor organs or muscles. As voluntary motion begins in the motor ganglia, these strictly constitute the motorium.

3. Intellective and emotive ganglia are inserted to give completeness of outline. These are the cerebral ganglia, in connection with which knowing and feeling occur. It is important to note the nerve-connections between the various ganglia. Though composed of a billion nerve-cells and five billion nerve-fibers, the brain is an organic unit. Marvellous structure! Truly our bodies are fearfully and wonderfully made!

Cerebral Action-Sensor Motor.-The thoughtful student will linger over this inside view of brain-activity in sensation and volition.

Place on the board the diagram on page 45 and the cut on page 46. Let each student trace sensor stimuli through each sensor line


to the mind; also trace motor stimuli through the motor apparatus to the outer world. Here patient work will reward effort.

The Five Special Sensor Lines convey impressions from the outer world to the inner world. They are called special, because each line opens up to us a new world. Each sensor line is called a sensor apparatus.

1. The optic apparatus consists of the eyes, the optic nerves, and the optic ganglia. Luminous bodies produce vibrations in luminiferous ether. Light-waves strike the retina, causing sensor light-currents. Molecular light-waves move through the optic nerves and agitate the optic ganglia. The mind feels the excitation, and knows that it feels it. The soul experiences the sensation of light. The mind, as intellect, interprets these sensations; perceives colors, forms, sizes.

2. The auditory apparatus embraces the ears, the auditory nerves, and the auditory ganglia. Vibrations of sonorous bodies produce sound-waves. The clock strikes. The sound-vibrations start sensor sound-waves

in the ear. The sensor waves vibrate through the auditory nerves and in the auditory ganglia. Self, as sensation, feels the excitation-hears the strokes; self, as intellect, interprets the sensations-perceives nine o'clock.

3. The olfactory apparatus includes the nose, the olfactory nerves, and the olfactory ganglia. Odor-waves caused by odorous bodies start, in the nose, sensor odorwaves. These waves vibrate through the olfactory nerves, and produce changes in the olfactory ganglia. The soul feels the excitation-experiences the sensa tions of odor; interprets the sensations-perceives sweet odors.


4. The gustatory apparatus consists of the mouth, the gustatory nerves, and the gustatory ganglia. Contact of the gustatory organs with articles possessing flavor excites gustatory nerve-currents. These currents pass molecular waves through the gustatory nerves and affect the gustatory ganglia. The conscious affection of the gustatory ganglia is the sensation called taste. Self, as

intellect, interprets these sensations-perceives sugar as sweet and grapes as delicious.

5. The tactile apparatus includes the skin, the tactile nerves, and the tactile ganglia. I touch the paper; the contact starts tactile waves which vibrate through the tactile nerves and in the tactile ganglia. The soul is conscious of the excitation-experiences tactile sensations. The soul interprets the sensations-perceives the paper as smooth.

General Sensor Lines. --The fifteen general sensor lines carry messages from the organs and tissues of the body. The excitant is within the body. For illustration we may take the

Muscular line. The muscular apparatus embraces muscles, muscular nerves, and muscular ganglia. Besides their contractile office, muscles seem to be sensitive to pressure or straining. The nerves which convey from the muscles to the muscular ganglia the sensor waves of pressure are called muscular nerves. We feel sensations of pressure or weight. It is still questioned whether the muscular should be classed as a special or a general sense. The student is left to study out and diagram the general sensor lines.

Comparative Psychology. You have taken a lively interest in the study of comparative anatomy and physiology. I trust that you will feel a still deeper interest in comparing human and brute mind. We have no sense which we do not find in some brute; and the senses of brutes, so far as we can judge, are affected in the same way as ours are, by the same objects. They may have some of the senses more acute than ours are, but they differ from ours only in degree, as the senses

of men differ in strength and delicacy. Acuteness of sensation is a characteristic of the lower animals. So far as we know, no brute has a sense that differs from ours in kind. If we judge, as we do in every other case, it must be plain to every observer that brutes have the same kind of enjoyment and suffering, through the senses, that men have. To heat and cold, hunger and thirst, food and poison, sickness, pain, and death they have the same bodily relations in kind that we have.*

Education of the Senses.-"The senses are all capable of being educated. Our tastes may become more delicate, and may keep us from using deleterious food. The sense of smell may be cultivated, and add to our enjoyments; and odors, especially by means of flowers, may be provided to gratify it. Hearing may be improved and made more sensitive and accurate. Music is a source of pleasure, which may be enhanced until it becomes elysian. Feeling may be made very delicate in its perceptions, and capable of distinguishing very nice differences of objects. The senses of pressure and of weight may be so trained as to give us very accurate measurements. But the eye is the most intellectual of all our sense-organs, enabling us at a glance to take in the vast and the minute, the near and the distant.

"All these should be cultivated by training in the family and at school. Children should be taught from their earliest years to use their senses intelligently and habitually. They should be encouraged to observe carefully the objects around them, and taught to describe and report them correctly. It has been said that there are more false facts than false theories, and this arises from persons not being trained to notice facts accurately, neither adding to them nor taking from them, nor gilding them by the fancy, nor detracting from them to serve an end. Pictures and models are used very extensively in modern education, and serve a good purpose, as they call in the senses to minister to the intellect. But the things themselves are vastly more instructive than any representation can be. So children should be taught to use their senses, especially their ears

*"See Instinct in Animals and Men," Chadbourne.

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