=Tobacco.=--Some people think tobacco is a food because it is made from the leaves of a plant. Other people think tobacco is a food because they do not feel hungry after smoking or chewing it. The truth is that tobacco is of no use to the body as a food and may do it much harm because of the poison it contains. Tobacco satisfies hunger somewhat by deadening the parts of the body that are calling for food. =Beer.=--The people who make beer and sell it say that it is a food. Men who have no interest in selling beer, and have experimented with it to find out whether it strengthens the body, say that beer should never be used as a food. It often tends to weaken the body. Children should never use beer at any time, and older people can sometimes avoid disease by letting it alone. PRACTICAL QUESTIONS 1. Which are the best meats for food? 2. Why should we not eat meat at every meal? 3. How should meat be cooked to make it most tender? 4. How is soup or broth made? 5. Name the best vegetables for food. 6. Name some good grain foods. 7. Of what use are fruits? 8. What can you say of the use of eggs? 9. How should eggs be cared for? 10. What can you say of the use of salt and pepper? 11. Why does tobacco satisfy hunger? 12. Of what value is beer for food? CHAPTER V HOW PLANTS SOUR OR SPOIL FOOD =Germs, Microbes, or Bacteria.=--The dust and dirt of all sorts contain thousands of tiny plants too small to be seen by the eye without help. An instrument called a _microscope_ makes them appear so large that their form and growth are easily studied. These little plants are called _germs_ or _microbes_. They are also named _bacteria_. They are so small that a million laid side by side would not cover the head of a pin. [Illustration: FIG. 16.--Bacteria or microbes found in water, dust, and waste. They help change straw and other dead matter into food for plants. Much enlarged.] There are hundreds of different kinds of germs. Some are round like little balls and others are the shape of tiny rods. Many of them which look just alike act very different in growing. There are more than twenty different kinds that grow in our bodies and cause diphtheria, tuberculosis, and other diseases. We have measles and scarlet fever because we have gotten these disease germs from some one else in whom they were growing. [Illustration: FIG. 17.--Mold which grew on moist bread in two days. 5, seed bodies breaking out of the sack; 1, 2, and 4, one of the seed bodies after one, two, and four hours' growth. Much enlarged.]