The problems handled by the Division of Laboratories and Infectious Diseases were both varied and vitally important in preventing wastage of troops. The view held by the experts of the division that the enteric group of diseases, which wrought such havoc in other wars, could be controlled by typhoid and paratyphoid inoculation and by adequate sanitary measures, was confirmed by the fact that, though typhoid occurred in the devastated and extremely insanitary regions along the Western Front, it never became a serious menace to the American Army. With the practical elimination of the enteric diseases, the respiratory diseases provided the most important problem for the Medical Department. The most vigorous measures were pursued in studying and attempting to control the incidence and mortality of respiratory diseases, and many facts were ascertained which proved of great value during the period of operations and which, when the lessons to be drawn from them have received sufficient study, will eventually place in our hands more adequate means of control. Epidemic cerebrospinal meningitis is another disease which always has to be feared when troops are mobilized. Infection is transmitted by the discharges from the respiratory passages, usually being disseminated by “carriers,” who spread the disease without having it themselves. In order to detect these “carriers,” any one of whom might unintentionally create as much havoc as an enemy agent in a munitions plant, hundreds of thousands of men were examined, our knowledge of the methods by which the disease is transmitted being thereby greatly increased. The problem presented by the venereal diseases has always been of vital interest to all armies and the fight against this class of infections has been vigorously waged in the American Army for many years. With the passage of the Draft Act it became evident that it would be necessary to extend the fight to the civilian population not only because it was a source of infection of the army but in order to diminish the occurrence of these diseases among drafted men. To accomplish this a close alliance was formed between the Section on Combating Venereal Diseases of the Medical Department and the War Department’s Commission on Training Camp Activities. The methods pursued in preventing venereal diseases aimed, first, at diminishing exposure to infection, and, second, at giving medical treatment to soldiers who have been exposed in order to prevent the development of the disease. One of the most immediately effective measures in preventing exposure was the repression of prostitution and its ally, the liquor traffic, in the neighborhood of army camps and to a lesser degree throughout the country. The surgeon-general assigned specially qualified officers of the Sanitary Corps, mostly lawyers, to the Law Enforcement Division of the Commission on Training Camp Activities, with orders to see that the federal and