Now let us take a good look at this coat and see if we can find out what it is like. The other day I saw some boys playing basketball. They wore short sleeves and short trousers. Four were Indians, and five were white boys, and one was a negro. The skin of the white boys seemed to shine, it looked so white; and the negro's shone in its blackness; but the Indian's looked a dull rich dusky brown. Yes, you say, they belong to different races. But what causes the difference in their color? Little specks of coloring matter, or _pigment_, which lie in the outer layer of the skin. Even white skins contain a little pigment, they are not a pure white. A Chinaman's skin has a little more of this pigment, so that it looks yellow; an Indian's has still more; and a negro's has most of all, making him black. Sunlight can increase the amount of pigment in the skin. The people who live in the torrid zone have much darker skins than those who live where the days are short and cold. You have noticed, yourself, that when you expose the skin of your face or arms to the hot sun, you become freckled, or tanned. This tanning, or browning, of the outer layer of the skin protects the more delicate coats of skin below from being scorched or injured by the strong light. When you are playing and running with your schoolmates, you see that their faces grow very red, and even their hands. Why is this? Because the heart has been pumping hard and has sent the red blood out toward the skin. The red color shines through the outer part of the skin. The pigment in the Indian's skin, or the negro's, prevents the red blood underneath from shining through, as it does through yours. [Illustration: THE PARTS OF THE SKIN The pore P on the surface of the skin is the end of a tube through which sweat flows out. At O are the oil sacs that feed the hair H. At B are the little blood vessels that make the skin look pink.] The skin, you see, is made up of different layers. When you burn yourself, you can see a layer of skin stand out like a blister. It is white; but if the blister is broken, underneath you see the coat that is full of tiny blood vessels, so tiny and so close together that this whole coat looks red. The skin, like every other part of the body, is made up of tiny animal cells. In the outer coat they become quite flat like little scales and then wear off; and their places are taken by the newer cells that are growing from beneath. The skin grows from beneath, and bit by bit it sheds its old outer coat. This is how it keeps itself nice and new on the outside and "grows away" the marks of cuts and burns.