12.  Effects of Alcohol and Tobacco upon the Lungs.—­Both alcohol and tobacco produce disease of the breathing organs.  Smoking injures the throat and sometimes causes loss of smell.  Serious and even fatal diseases of the lungs are often caused by alcohol.

13. Many people suppose that the use of alcohol will save a man from consumption.  This is not true.  A man may become a drunkard by the use of alcohol, and yet he is more likely to have consumption than he would have been if he had been a total abstainer.  “Drunkard’s consumption” is one of the most dreadful forms of this disease.

SUMMARY.

1.  Pure air is as necessary as food and drink.

2.  Anything which is rotting or undergoing decay causes a bad odor, and thus makes the air impure.

3.  Foul air contains germs which cause disease and often death.

4.  Persons sick with “catching” diseases should be carefully avoided.  Such persons should be shut away from those who are well, and their rooms and clothing should be carefully cleansed and disinfected.

5.  The breath poisons the air about us.  Each breath spoils half a barrelful of air.

6.  We should change the air in our houses, or ventilate them, so that we may always have pure air.

7.  We should always keep the body erect, and expand the lungs well in breathing.

8.  The clothing about the chest and waist should be loose, so that the lungs may have room to expand.

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 of the tree.  When the bare place heals over, an ugly scar will be left.