=The Value of Sound Teeth.=--Sound teeth which will do good work in chewing food are worth more than a foot or an arm. If the foot or arm is lost, the body is likely to get well and be as healthy as ever. _The health of the whole body depends upon the work done by the teeth._ Unless they do their part the stomach cannot get the food ready for the blood. A part of badly chewed food is turned into a poison farther down in the food canal. This is what makes many people feel so tired and miserable much of the time. Hundreds of men have been refused admission to our army because they have poor teeth. Soldiers must be strong and well to take long marches and fight battles. Sound teeth give strength and health. PRACTICAL QUESTIONS 1. Why should the mouth be washed out every day? 2. When do the milk teeth appear? 3. When are the milk teeth lost? 4. How many teeth have you? 5. How many show signs of decay? 6. How may toothache be prevented? 7. How may the teeth be kept sound? 8. Why do sweets cause the teeth to decay? 9. How should you brush your teeth? 10. Why should the dentist examine your teeth every year? 11. Why are sound teeth of great worth? CHAPTER IX ALCOHOLIC DRINKS =Drink needed for Health.=--Water in the form of sweat and in other ways is constantly passing off from the body. This water carries with it the waste matter which, if it remained, would poison the body. There is some water in the food we eat, but not enough to supply the wants of the body. Some persons think that the body needs beer or wine to keep it in good order. These liquids, as well as whisky, brandy, and rum, are called _alcoholic drinks_. The latest experiments and studies show that the body never needs alcoholic drinks to keep it in the best of health. These drinks sometimes make the body sick, and if much alcohol is taken at one time, the person becomes dizzy, staggers, and may fall down and go to sleep. =The Desire for Drink.=--When parts of the body have too little water, there is a longing for drink. This is called _thirst_. As soon as a cup of water is drunk the desire is satisfied. There is no danger of drinking too much pure water. Persons who have been accustomed to use alcoholic drink have a thirst which water does not satisfy. It is an _unnatural thirst_. Even beer or wine will not satisfy such a thirst except for a few minutes. Very often a person's thirst is not satisfied until he has used so much wine or whisky that he becomes dull and unsteady in his walk. He is then said to be drunk. [Illustration: FIG. 35.--Yeast plants growing as in the making of beer and wine. Much enlarged.]