9. Always breathe through the nose.

10. Tobacco causes disease of the throat and nose.

11. Alcohol causes consumption and other diseases of the lungs.




CHAPTER XV.

THE SKIN AND WHAT IT DOES.


~1. The Skin.~--The skin is the covering of the body. It fits so exactly
that it has the precise shape of the body, like a closely fitting
garment. If you will take up a little fold of the skin you will see that
it can be stretched like a piece of india-rubber. Like rubber, when it
is released it quickly contracts and appears as before.

~2. The Bark of Trees.~--Did you ever peel the bark off of a young tree?
If so, you have noticed that there were really two barks, an outer bark,
as thin as paper, through which you could almost see, and an inner and
much thicker bark, which lay next to the wood of the tree. You can peel
the outer bark off without doing the tree much harm. Indeed, if you will
notice some of the fruit or shade trees in the yard, at home, you will
see that the outer bark of the tree peels itself off, a little at a
time, and that new bark grows in its place. If you tear off the inner
bark, however, it will injure the tree. It will make it bleed, or cause
the sap to run. The sap is the blood of the tree. The bark is the skin