Next to water, milk has been in the past the most pro­lific source of food-borne diseases; and the hygienic value of milk as a food makes it doubly necessary that all possible steps should be taken to avoid danger from this source. There are three distinct ways in which milk causes disease, (1) by the transmission of pathogenic germs from the cow to man; (2) by the dissemination of the germs of the specific communicable diseases of man, and (3) by the production in infants of the summer diarrheas caused by non-specific microbes of putrefaction.