MOTHER: Just think of driving nails into muscles! Yet you see our body-houses must have some kind of a covering. It must be thin and strong and one that will stretch. Look at your hands and see if they do not have the very best covering that could be made. Pinch up the skin, and see how thin it is, and yet how well it fits every part of the body. AMY: And the skin stretches, mother. See, I can bend my knee and elbow, and move my fingers as I please. MOTHER: Yes, it is like a close-fitting garment. What we call the skin is really _two_ skins. You see I can put a pin through the outer skin in the palm of my hand, and I feel no pain, and you see no blood. HELEN: Isn’t that all the skin we have? MOTHER: No; for under this thick, outer skin is what is called the true skin. It has such fine blood-vessels that if you could see them, they would look like fine network. If you should prick this _inner_ skin it would hurt, and the blood would flow. This shows it has nerves as well as blood. Under the true skin is a layer of fat. This is like a warm woolen garment to keep the body warm. Between the outer skin and the true skin there is some jelly-like coloring matter, which gives it color. HELEN: Is that why some persons are very dark and others are light, mother? MOTHER: Yes; your true skin is just the same color as that of the negro and the Indian. The coloring matter under the outer skin is all that makes the difference. This outer covering is made of little horny scales laid one over another, much as a roof might be if it had ten or twelve layers of shingles. The outer scales keep wearing away all the time, and new ones take their places. You know a snake sheds its skin and crawls away with a new one. We shed our skin, too, little by little, but the scales are so small we can hardly see them. If you should wear your under-clothing several days, and then shake it in the sunlight, you would see little scales floating about in the air like dust. AMY: Isn’t the skin thicker in some parts of the body than others? MOTHER: Yes; on the palms of your hands and the soles of your feet it is quite thick, while on the lips and some other parts of the body it is very thin indeed. Have you noticed how the skin looks if it is scratched and then heals up? ELMER: Just the same as it did before. MOTHER: But if there is a deep cut or a severe burn, how does it look after it heals? HELEN: There is a scar left. MOTHER: This shows that the outer skin and the coloring matter will come back as they were before if they are hurt; but when the true skin is injured, the blood makes a kind of patch, which we call a scar. Another curious thing about the true skin is that it has tiny muscles, and when the body is cold, they draw up and make little hillocks, which we call “goose-flesh.” But the skin is very useful, besides being a covering for the body. When we were getting dinner to-day, what did we do with the potato parings and other things we did not wish to keep?