22. It would be too much trouble for the large brain to stop to think every time we step, and the little brain has work enough to do in taking care of the heart and lungs and other organs, without keeping watch of the feet when we are asleep, so as to pull them up if some mischievous person tickles them. So Nature puts a few nerve cells in the spinal cord which can do a certain easy kind of thinking. When we do things over and over a great many times, these cells, after a time, learn to do them without the help of the large brain. This is the way a piano-player becomes so expert. He does not have to think all the time where each finger is to go. After the tunes have been played a great many times, the spinal cord knows them so well that it makes the hands play them almost without any effort of the large brain.
1. The part of the body with which we think is the brain.
2. The brain is found filling the hollow place in the skull.
3. There are two brains, the large brain and the small brain.
4. Each brain is divided into two equal and complete halves, thus making two pairs of brains.
5. The brain is largely made up of very small objects called nerve or brain cells.
6. The nerve cells send out very fine branches which form the nerves.
7. The nerve branches or fibres run to every part of the body. They pass out from the brain to the rest of the body through a number of openings in the skull.
8. Most of the nerve branches pass out through a large opening at the back of the skull, in one large bundle called the spinal cord.
9. The spinal cord runs down through a canal in the backbone, and all along gives off branches to the various parts of the body.
10. It gives us pain to prick or hurt the flesh in any way, because when we do so we injure some of the little nerve branches of the brain cells.
11. When we suffer, we really feel a pain in the brain. We know this because if a nerve is cut in two, we may hurt the part to which it goes without giving any pain.
12. We have different kinds of nerves of feeling.
13. There are other nerves besides those of feeling. These are nerves of work.
14. The nerves of work have charge of the heart, the lungs, the muscles, the liver, the stomach, and every part of the body which can work or act.
15. The brain and nerves control the body and make all the different parts work together in harmony, just as a general controls an army.
16. The brain uses the nerves very much as a man uses the telephone or telegraph wires.
17. With the large brain we remember, think, and reason.
18. The little brain does the simple kind of thinking, by means of which the heart, lungs, and other vital organs are kept at work even when we are asleep.