Page:First course in biology (IA firstcourseinbio00bailrich).pdf/577

 much is eaten. There is a common tendency to exaggerate the importance of dietetics.

Indigestion.—I. A Fetid Breath. 1. Name three causes of bad breath. 2. Let us investigate whether indigestion could cause a bad breath. In what kind (two qualities) of weather does meat spoil the quickest? 3. Suppose that meat or other food is put into a stomach with its gastric glands exhausted and its muscular walls tired out, what will be the rate of digestion, and what might happen to the food? 4. Odorous contents of the stomach (e.g. onion) can be taken by the blood to the lungs where it will taint the breath.

After answering the above questions, write in a few words how indigestion may cause a bad breath.

II. A Coated or Foul Tongue. 1. When the doctor visits you, at what does he first look? 2. What sometimes forms on old bread? (p. 158.) 3. Do you think such a growth possible on undigested bread in the stomach? 4. The microscope shows the coating on the bread to be a growth of mold. If it forms on the walls of the stomach, it may extend to what?

III. Stomach Ache. 1. How can you tell whether fruit preserved in a sealed glass jar is fermenting? 2. What connection is there between belching after eating too freely of sweet or starchy food, and the observation above? 3. A muscle gives pain when it is stretched. Why does belching sometimes give relief to an uneasy stomach? 4. Can you, by using these facts, explain a cause of stomach ache?

For what Kind of Man were the Human Digestive Organs created?—That food is best to which the food tube has been longest accustomed. It would be of the greatest value as a guide to diet if we knew the food eaten by early man during the many ages when he led a wild life in the open air. The organs of early man were doubtless perfectly adapted to the life he led. The food tube is adapted to the needs of those long ages, for a few centuries of civilization cannot change the nature of the digestive organs; yet some people disregard natural appetites and try to force the digestive organs to undergo greater changes in a few months than centuries could bring about.

To test whether an Article of Food belonged to Man's Original Diet.—Scientists agree that the human race began in a warm country; that early man was without gristmills, stoves, or fire, and ate his food raw. If an article of food is pleasant to the taste in its raw, pure state, there is little doubt that it, or a similar food, was eaten by primitive man before he knew the use of fire in preparing his food. Apply this test to the following foods, underlining those foods that pass the test: apples, bananas, lettuce, turnip greens, turnips, fruits, nuts, beef, fowls,