~12.~ The mouth and teeth should be carefully cleansed immediately on rising in the morning, and after each meal. All particles of food should be removed from between the teeth by carefully rubbing both the inner and the outer surfaces of the teeth with a soft brush, and rinsing very thoroughly with water. A little soap may be used in cleansing the teeth, but clear water is sufficient, if used frequently and thoroughly. The teeth should not be used in breaking nuts or other hard substances. The teeth are brittle, and are often broken in this way. The use of candy and too much sweet food is also likely to injure the teeth. ~13.~ Some people think that it is not necessary to take care of the first set of teeth. This is a great mistake. If the first set are lost or are unhealthy, the second set will not be as perfect as they should be. It is plain that we should not neglect our teeth at any time of life. ~14. Tobacco.~--When a person first uses tobacco, it is apt to make him very sick at the stomach. After he has used tobacco a few times it does not make him sick, but it continues to do his stomach and other organs harm, and after a time may injure him very seriously. Smokers sometimes suffer from a horrible disease of the mouth or throat known as cancer. ~15. Effects of Alcohol upon the Stomach.~--If you should put a little alcohol into your eye, the eye would become very red. When men take strong liquors into their stomachs, the delicate membrane lining the stomach becomes red in the same way. Perhaps you will ask how do we know that alcohol has such an effect upon the stomach. More than sixty years ago there lived in Michigan a man named Alexis St. Martin. One day he was, by accident, shot in such a way that a large opening was made right through the skin and flesh and into the stomach. The good doctor who attended him took such excellent care of him that he got well. But when he recovered, the hole in his stomach remained, so that the doctor could look in and see just what was going on. St. Martin sometimes drank whiskey, and when he did, the doctor often looked into his stomach to see what the effect was, and he noticed that the inside of the stomach looked very red and inflamed. ~16.~ If St. Martin continued to drink whiskey for several days, the lining of the stomach looked very red and raw like a sore eye. A sore stomach cannot digest food well, and so the whole body becomes sick and weak. What would you think of a man who should keep his eyes always sore and inflamed and finally destroy his eyesight by putting pepper or alcohol or some other irritating substance into them every day? Is it not equally foolish and wicked to injure the stomach and destroy one's digestion by the use of alcoholic drinks? Alcohol, even when it is not very strong, not only hurts the lining of the stomach, but injures the gastric juice, so that it cannot digest the food well.