Milk is not a beverage. It is a food. A quart of milk contains as much food and fuel value as eight eggs or twelve ounces of lean beef. That is, a cupful (one-half of a pint) is equal to two eggs or three ounces of lean beef. This shows that milk should not be taken to quench thirst, but to supply nourishment. Milk is one of our most satisfactory and economical albuminous foods, even at the present high prices. In many foods from 5 to 10 per cent of the protein goes to waste. In milk the waste does not ordinarily amount to more than about 1 per cent. This fluid generally leaves the stomach within one or one and one-half hours after being ingested. In spite of its merits as a food some writers on dietetics advocate that adults stop using it, giving it only to the young. Milk is an excellent food when properly used. When abused it tends to cause discomfort, disease and death, and so does every other food known to man. Milk is given in fevers and in other diseases, when the digestive and assimilative processes are suspended. This is a serious mistake and has caused untold numbers of deaths. When the digestion has gone on a strike all feeding is destructive. Milk and meat broths, which are generally given, are about the worst foods that could be selected under the circumstances, for they decay very easily, and are excellent food for the numerous bacteria that thrive in the digestive tract during disease. These foods must decay when they are not digested, for the internal temperature of the body during fevers is over one hundred degrees Fahrenheit. When bacteria are present in excess they give off considerable poison, which makes the patient worse. If circumstances are such that it is necessary to feed during acute disease, which is always injurious to the patient, let the food be the least harmful obtainable, such as fruit juices. Even they do harm. In our country cow's milk is used almost exclusively, and that is the variety that will be discussed in this chapter. In other lands the milk of the mare, the ass, the sheep, the goat and of other animals is used. Human milk is discussed in detail in the chapter on Infancy. The objection voiced against cow's milk is that it is an unnatural food for man, only fit for the calf, which is equipped with several stomachs and is therefore able to digest the curds which are larger and tougher than the curds formed from human milk. It is said that the curds of cow's milk are so indigestible that the human stomach can not prepare them for entry into the blood. This is probably true, but it is also true of other protein-bearing foods. The digestion and assimilation of proteins are begun in the stomach and completed in the intestines, and the protein in milk is one of the most completely utilized of all proteins.