~20. What the Little Brain Does.~--The little brain[B] thinks too, but it does not do the same kind of thinking as the large brain. We may use our arms and legs and many other parts when we wish to do so; and if we do not care to use them we may allow them to remain quiet. This is not the case with some other organs. It is necessary, for example, that the heart, the lungs, and many other organs of the body should keep at work all the time. If the large brain had to attend to all of these different kinds of work besides thinking about what we see, hear, and read, and other things which we do, it would have too much work to do, and would not be able to do it all well. Besides, the large brain sometimes falls asleep. So the large brain lets the little brain do the kinds of work which have to be attended to all the time, and the little brain keeps steadily at work when we are asleep as well as when we are awake. ~21. What the Spinal Cord Does.~--If you tickle a person's foot when he is asleep, he will pull it up just as he would if he were awake, only not quite so quickly. What do you suppose makes the muscles of the leg contract when the brain is asleep and does not know that the foot is being tickled? And here is another curious fact. When you were coming to school this morning you did not have to think about every step you took. Perhaps you were talking or looking over your lessons; but your legs walked right along all the time, and without your thinking about them. Can you tell how? ~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. SUMMARY. 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.