the breathing is shallow, the muscles are tired from remaining a long time in one position, the heartbeat is slow, and the brain is beginning to tire. A person in this condition feels sleepy and dull, and he can learn little by sitting and looking at his book. If, however, he will stand up and spend a few minutes in stretching and breathing exercises, he will find himself feeling much better. The breathing will become deeper, the heart will beat more rapidly and with more force, and the tired muscles will feel rested. The brain and the body are "waked up," and the person can go back to work, feeling greatly freshened and rested. Several times a day every one in a schoolroom should spend a little time in such exercises as are described in Chapter Twenty-seven. While this is being done, all the windows should be thrown wide open and the fresh outside air allowed to fill the room.

Questions: I. What are some of the benefits of exercising? 2. What is the best place to take exercise? 3. Why should those who live in cities make use of the parks and open-air playgrounds? 4. Why is it unwise to exercise immediately before or after a meal? 5. Give three good rules in regard to exercise. 6. In what games or sports do the players sometimes injure themselves by too much exercise? 7. What is the best way to rest after you have become tired of study?

Suggestions and topics for development: The exercise that pupils take during play hours. The wisdom of supplying school and municipal playgrounds.

THE NERVOUS SYSTEM

If an army had no officers, and each soldier marched as he pleased and camped where he pleased, we should not call it an army at all, but a mob; and if the whole army attacked the enemy without plan or purpose, each man fighting in his own way, we should not expect it to win many victories. If an army is to stand before an enemy, it must have a general over it who will keep all its parts working together.

The human body is composed of many organs, and as all the parts of an army must be made to work together, so must all the organs of the body be made to work together. Over all the body, therefore, a ruler has been set to govern the organs and to make them do their work when it needs to be done. This ruler is the nervous system. It is made up of the brain and spinal cord, and of the nerves, which run out from the brain and spinal cord to all parts of the body.

The brain and the spinal cord. The center of the nervous system is the brain and the spinal cord. The brain is enclosed by the cranium or bones of the head. The spinal cord lies in a canal in the spinal column. The brain and the cord are very soft and delicate, and they are protected by the strong bones about them.

Nerves and their work. From the brain and spinal cord the nerves run out and branch until

they reach every muscle and the smallest parts of every organ. The work of the nerves is to carry messages between the brain and the other parts of the body. If you stick a pin into your finger, some of the thousands of nerves that end in the skin take a message to the brain. You then know that the finger was hurt. If you wish to lift your hand, your brain sends a message down the nerves to the muscles of your arm and causes them to move the hand. So whenever we hear, see, taste, smell, or feel, or whenever we move, we do so because the nerves carry messages either to or from the brain.

The work of the brain. The brain is the great center of the nervous system. It governs the heart and lungs. It gives us power to move when we wish to do so. It makes us able to see and to hear, to think and to feel, to know and to understand. Without the brain we should have no knowledge of where our hands and feet are, we could feel neither heat nor cold, and we should always remain in one place as does a tree. The mind of man has made him the ruler of the world, but without the brain the mind would be gone. There would then be no joy or love or knowledge in us, and our whole existence would be like the existence of a stone.

Questions: 1. Why must the body have a ruler to govern it? 2. What is the ruler of the body called? 3. Name the chief parts of the nervous system. 4. Where is the brain? 5. Where is the spinal cord? 6. How are the brain

and spinal cord protected? 7. What is the work of the nerves? 8. Explain what happens in the nerves when you stick a pin into your finger. 9. When you wish to move a part of the body. 10. Explain the work of the brain. II. What would life be like without a brain?

Suggestions and topics for development: The resemblance of the nervous system to a telephone system. Make clear the fact that the brain is nourished in the same way as the other parts of the body, and that there is no such thing as a brain food.

The chapter on Habit either in James' Psychology for Teachers or in James' Talks to Teachers (both published by Henry Holt and Company, New York) gives a vivid picture of the changes brought about in the nervous system by our activities. A reading of this chapter will assist the teacher in getting a clear idea of the nervous system and its workings. A point that is worthy of emphasis is that the primary function of the nervous system is to drive the muscles and that muscular exercise is most important in keeping the nervous system in health.

In connection with the teaching of the following chapters, the teacher should bear in mind the necessity of proper conditions for the formation of correct habits. For example, many cases of drooping carriage of the head are due to near-sightedness; and recently it has been stated that some children thrust their heads forward on account of annoyance caused by the rubbing of the clothing on the back of the neck, and that in these cases the faulty carriage can be corrected by cutting the garments low in the back. It is undoubtedly true that the conditions in which children live and work have much to do with the physical, mental, and moral habits that they form. The teacher should therefore see that, as far as possible, school conditions make easy the formation of correct habits.