Intensive training and clinical opportunities were provided for instruction in new methods in war surgery and fractures and in the treatment of infected wounds; there were schools for the training of medical officers in the use of X-rays; of laboratory specialists; for special work with diseases of the heart; for treatment of pneumonia and of those infectious diseases that are of frequent occurrence when large bodies of men are brought together. A particularly determined effort was made along preventive lines to lessen in the American Army both at home and in France the menace of venereal disease, always feared for its power to lower the efficiency of armies. Instruction by various means, an incessant campaign of vigilance by specially trained physicians, treatment of infected men, military punishment of offenders, endeavors to control the surroundings of camps, all were among the methods with which this scourge of all armies was combated, with remarkable success. The percentage of such diseases in the Army was below what it is in civilian life and very much below that of its prevalence in the Allied Armies. One of the schools made necessary by the new methods of training instituted in the American Army was that for the instruction of military psychologists who were needed for the work of examining the men, as they came from their local boards and were inducted into the training camps, in order to eliminate those mentally unfit for army service and grade those accepted according to their mental qualifications, for the information of their officers, as already described in the chapter on “The Making of the Army.” Under the supervision of the Medical Corps, this school trained many officers for psychological work at the cantonments, the course lasting two months. This development, an American idea, was something new in the making and training of armies, but it proved its value in the higher efficiency gained by enabling officers to select for special duties the men best fitted for them and so increasing the efficiency of the fighting units. A new development of wartime medical science was made necessary by air warfare which soon brought into being the flight surgeon who kept under his observation the men in training at flying fields. So important did this division of the Medical Corps quickly become that special facilities were provided for the training of flight surgeons and laboratories were established for the investigation of the medical problems connected with the air service.