HYGIENE OF DIGESTION 245 



very powerful in purifying the alimentary canal. (Fruits 

 have almost no proteid. How does this show that a fruit 

 diet would starve the germs, even if the fruit acids did not 

 destroy them ?) (3) They contain very valuable mineral 

 salts that are of highest use to the blood and tissues. 

 (4) The carbohydrate in ripe fruits is all in the form of 

 levulose or fruit sugar, which is predigested starch, and is 

 absorbed without digestion. With these advantages, there 

 is the disadvantage that fruits are largely water, so that 

 the nutriment they contain is very scant, except in the case 

 of grapes, bananas, and olives. 



438. The proverb that fruit is golden at breakfast, silver 

 at noon, and lead at night, is not true. Fruit is golden at 

 all times, if it is sound and ripe, and if the stomach is not 

 already filled with food. Fruit juices are valuable as restor- 

 atives .to health, since they tax the digestive organs very 

 little and are quickly assimilated. Since germs will not 

 grow in fruit juices, a fruit diet for several meals will dis- 

 infect the alimentary canal and ward off a "bilious" attack. 

 Juicy apples, pears, lemonade, orangeade, pomegraniteade, 

 ripe peaches, etc., are pleasanter than medicines. 



439. Animal Food. Meat. Proteid is the principal food 

 substance in meat. Beef contains the largest amount of 

 any of the common meats, and pork the least. The fat of 

 meat is also of great importance : fat is abundant in pork. 

 Meat that is salted and smoked, or dried, or prepared in 

 any way so that germs will not grow in it, can be kept for 

 a long time, but its digestibility is greatly impaired. This 

 is because its fibers have been hardened so that the gastric 

 juice cannot readily penetrate them. Meat which has much 

 connective tissue is tough ; the most tender and digestible 

 of meats consist almost wholly of muscular tissue and fat. 



440- Experiments show that ordinarily one fifth of the 

 proteid in vegetable food passes through the intestine un- 

 digested and unabsorbed, and is thus wasted, while only 



