The acids of fruits give to them their delightful and appetizing flavors. Fruits in the unripe state contain tannic acid, a marked astringent. The gastric and peristaltic woes of the small boy the night following the green apple episode are due to the tannic acid the unripe fruit contains. The three chief acids of fruit are citric acid, found in oranges, lemons, and grapefruit; malic acid, as found in apples, pears, peaches, and similar fruits; and tartaric acid, as found in grapes. These are organic acids, recognized and readily digested by the body. The acids of fruits are remarkable peptogens; that is, they stimulate the appetite and promote the flow of the digestive juices. Fruit acids are most efficient disinfectants. Some years ago, an eminent medical authority of this country, in a representative medical gathering, said, "We are as yet without a satisfactory medicinal intestinal disinfectant." In fruit acids, we possess such an agent in a most desirable form. No germ, disease-producing or otherwise, can live in the presence of fruit acid. Fruit acids can be taken practically _ad libitum_. Fruit acids taken freely by mouth or diluted and injected into the bowel, most efficiently asepticize the intestinal canal. Three or four pints of water to which the juice of one lemon has been added, injected into the bowel following a cleansing enema, will thoroughly destroy disease-producing bacteria in the colon. Flushing the bowel frequently with such a solution is one of the most efficient known means of successfully combating the fetid summer diarrheas of children. The proteid or nitrogenous element of fruits, as well as their fatty element, may be passed over with little consideration. Fruit contains little proteid; and aside from the olive, there is almost no fat in fruit. The fat of the ripe olive, however, is one of the most delicious and digestible forms of fat. Ripe olives contain about fifty per cent fat. Olive oil can be mixed with water; therefore it readily mixes with the intestinal juices, and is most easily digested. _Fruit Salts_ The salts of fruit are most desirable, being so essential in tissue building. Some of the most important of these salts are potash, lime, phosphoric acid, and iron. Deficiency of the lime salts in the bones of children produces conditions of bone softening, or rickets. This can be largely prevented by adding fruit to the diet of these afflicted children, using especially grapes, oranges, lemons, and grapefruit, which contain high percentages of lime salts. The condition of anæmia is a lack of iron in the blood. This cannot be replaced by medicinal or metallic iron, as the body is unable to appropriate these inorganic substances; but the iron in fruit is perfectly adapted to the body needs. Plums, cherries, and especially strawberries and currants contain considerable iron, and are most helpful in the treatment of anæmic conditions.