Milk is a complex food, highly organized, and therefore is easily injured or spoiled. The general rule is that the more complex a food is, the more easily it spoils. It is rather difficult at present to get wholesome milk enough to supply the people of our large cities. When it is boiled, the milk keeps longer, but boiled milk is spoiled milk. The fine flavor is lost, the casein, which is the principal protein of milk, is toughened, the milk, which is normally a living liquid, is killed, the chemical balance is lost, the organic salts being rendered partly inorganic. Milk that is unfit to eat without being boiled is not fit to eat afterwards, for the poisonous end products of bacterial life remain. The milk is soured by the bacteria it contains. The lactic acid bacteria are harmless. When there is a lack of care and cleanliness, other bacteria get into the milk, and these are also harmless to people in good health, and most of them are not injurious to sick people. The bacteria (germs) do not cause disease, but when disease has been established, they offer their kindly offices as scavengers. Bacteria thrive in sick people, especially when they are fed when digestive power is lacking. Boiling retards the souring of milk, but when fat and protein are boiled together the protein becomes hard to digest. Milk is rich in both fat and protein. Excessive heat turns the milk brown, the milk sugar being carameled. Babies do not thrive on boiled milk. They may look fat, but instead of having the desirable firmness of normal children, they are puffy. Children fed on denatured milk fall victims to diseases very easily, especially to diseases which are due to lack of organic salts, such as rickets and malnutrition. Pasteurization of milk is very popular. This is objectionable for the same reasons that boiling is condemned, though not to the same extent. Pasteurization is heating the milk to about 140 to 150 degrees Fahrenheit. This kills many of the bacteria, but many escape and when the milk is cooled off they begin to multiply and flourish again. It is estimated that pasteurized milk contains one-fourth as many bacteria as natural milk. So nothing is gained, and the milk is partly devitalized. The advocates of pasteurization give statistics showing that milk so treated has been instrumental in decreasing infant mortality. But please bear in mind that previously a great deal of milk unfit for consumption was fed to the babies. Those who pasteurize milk generally are careful enough to see that they get a good product in the first place.