THE NERVOUS SYSTEM

BY

SUSANNA COCROFT

Perhaps no part of the body is less understood than the nervous system; yet, due, partially, to the advance in surgery and the necessity of relieving the danger of the effect of the anesthetic upon the heart, investigations and experiments upon the nerves are engrossing the attention of scientific men. These experiments have led to a network of theories, with, as yet, few definite deductions.

The anatomy is fairly clear but the chemistry of the nerves and the physiological action, in the manner of conveyance of sensations to nerve centers in the spinal cord and the brain, the return of the motor impulse to the extremities, and the nature

of impulse incited by thought and emotion, are veiled in obscurity. The manner of thought production, as well as the manner of the transference of this thought to the nerves, and through the nerves to the muscles or to the vital organs, has also thus far eluded the definite deductions from scientific experiments.

Thoughts and thought influence, belong to the realm of psychology; the purpose of this lecture is to deal with such phases of the nervous system as the many experiments have proven to bé facts.

The nervous system of man may very aptly be compared to the telephone system of a large city. The different wires in local districts of a city are collected into one local central office for that section. All local centrals are collected at one point and controlled by one Grand Central Station. The collections of nerve cells in the spinal cord, known as nerve centers, correspond to the local centrals,—the nerve fibres correspond to the wires. The brain is the Grand Central and is connected, through the nerve centers, with every part

of the body, except the hair, the nails and the enamel of the teeth;-the hair and nails give no sensation when cut.

When the telephone receiver is removed from the hook, a signal traverses the wire; this signal is received by the local central, and the reply is sent back over the same wire to the party giving the signal. In like manner, when a pressure is made upon a nerve in any part of the body, for example, if the finger be burned, the disturbance is called a sensation; this sensation is transmitted through the nerve fibre to a nerve center in the spinal cord, and the nerve center at once sends a reply through the same nerve trunk telling it to contract the muscles and draw the finger away. All sorts of messages, of varying importance, are sent to the spinal nerve centers, or local centrals. When they are of sufficient importance, or are unusual, the nerve centers call up the Grand Central, or brain, which answers the message; by far the greater number of messages, however, are answered by the nerve centers, without disturbing the brain.

On the other hand, the brain gives direct orders to the extremities through a local center, without having been called up by the extremity. Thoughts, in some mysterious way, direct such messages.

AUTHOR'S NOTE: I would advise a very careful reading of this book. Do not attempt to skim through it. The subject embraced is one of the most important studies, as knowledge of the construction and functions of the Nervous System is essential to success in cultivation of our physical selves. I have made every statement as simple and clear as the English language permits and have avoided where possible, all technical words. However, it is absolutely necessary to use some of these words, because words in ordinary usage will not exactly express the ideas. Read it several times; it will become clearer each time you read it.