Milk is a perfect food for the infant because it contains the elements in proper proportions to sustain life and growth, though, alone, it is insufficient for the nourishment of healthy adults. The adult, in order to get sufficient nutriment, would be compelled to take a larger proportion of water than necessary, the proportion of water required by the system being about sixty-seven per cent., while milk contains eighty-seven per cent. In many diseases, however, a whole or partial milk diet is desirable, especially in any inflammatory condition of the gastro-intestinal tract. TABLE X MILK AND MILK PRODUCTS ———————————————+———————+—————————+——————+———————+———————+———————————— FOOD MATERIALS | Water | Protein | Fats | Sugar | Salts | Lactic Acid ———————————————+———————+—————————+——————+———————+———————+———————————— Milk | 86.8 | 4.0 | 3.7 | 4.8 | 0.7 | .... Skimmed milk | 88.0 | 4.0 | 1.8 | 5.4 | 0.8 | .... Buttermilk | 90.6 | 3.8 | 1.2 | 3.3 | 0.6 | 0.3 Cream | 66.0 | 2.7 | 26.7 | 2.8 | 1.8 | .... Cheese | 36.8 | 33.5 | 24.3 | .... | 5.4 | .... Butter | 6.0 | 0.3 | 91.0 | .... | 2.7 | .... ———————————————+———————+—————————+——————+———————+———————+———————————— The milk of the cow is not perfectly adapted for the young child—it is lacking in the proper proportion of sugar, and when fed to the infant it must be modified. Mother’s milk is not only richer in sugar than cow’s milk, but it contains about half as much casein. The calf needs more albumin than the baby does because it grows faster. Human milk is also richer in fat. An all-milk diet may be followed when it is desirable to gain in weight. Such a diet should be accompanied by exercises for the vital organs and by deep breathing, but experiments have shown that healthy digestive organs do their work better when a part of the food is solid. A milk and cream diet of about three quarts milk and one quart cream with the addition of one to two eggs a day will keep up the strength of one in bed, but is not sufficient for one who is active. In order for an adult to obtain the proper quantity of carbohydrates and fat, from an all-milk diet, it is necessary for him to drink from four to five quarts of milk a day (sixteen to twenty glasses). It is usually said that on an all-milk diet an active person requires as many quarts as he is feet tall. Young babies on mother’s milk are almost always fat, because of the larger proportion of sugar and fat in the mother’s milk. Reference to Table X shows that the thirteen per cent. of solids are about equally divided between fat, sugar, and protein. The sugar is lactose. It supplies heat to the infant before it can exercise its muscles vigorously. The protein is casein. There is no starch in milk. The digestive ferment, which acts on starch, has not developed in the young babe and it cannot digest starch.