The dangers which are feared in milk are of course connected with the distribution of disease. Most persons who thus hesitate to use milk have simply a vague fear, without knowing just what is to be feared. When we put together all the facts in our possession we find that there is good reason for believing that milk is sometimes concerned in the distribution of the following well-known diseases and some obscure ones: The first is _tuberculosis_, which is a disease attacking the cow, and, if located in the mammary gland, may infect the milk with tubercle bacilli, and may subsequently produce the disease in the person who drinks the milk. It should be stated, however, that there is good reason for believing that the danger from this source has been overrated. Second, we have _diphtheria_, which apparently may also attack the cow. The diphtheria germs may get into the milk from the cow, and they certainly do get into the milk occasionally from secondary sources. _Scarlet fever_ apparently is distributed by milk, though whether this disease may come from the cow or only by secondary contamination of the milk is not yet positively settled. _Typhoid fever_ has in a large number of cases been traced to the milk supply. This disease, however, does not occur in the cow, and the germs always get into the milk from a secondary source, such as water or contact with a person who has the disease. _Cholera_ may be distributed by milk, but this is of course of little importance. Of these disease bacteria, the tubercle bacillus probably never grows in milk, while the typhoid and diphtheria germs do. The most common of all troubles attributed to milk are those somewhat obscure _intestinal diseases_ which attack people especially in the summer months, and are particularly common among children. Prominent among these stands _cholera infantum_. These latter troubles, according to our present knowledge, are not produced by distinct species of bacteria finding entrance into the body and growing there, as are the other diseases mentioned. They appear to be produced by bacterial poisons which are in the milk. The bacteria--probably several different varieties--grow in the milk and there give rise to certain poisonous products, and these, when taken into the stomach, produce the diarrhoeal diseases referred to.