to bacteriology the technique necessary for its rapid development. Koch was called to the Imperial Board of Health in Berlin in 1880, and started the first laboratory founded for the study of bacteriology and public health problems. In this laboratory, methods of studying and photographing bacteria were developed, methods of disinfection based on the knowledge of spore resistance were elaborated, and the study of the bacteriology of individual diseases inaugurated. As a result of the latter activity, he announced, in 1882, the discovery of the bacillus of tuberculosis, and it is not too much to say that his announcement astounded and profoundly stirred the entire civilized world. In the same year Löffler and Shütz announced the discovery of the bacillus of glanders, and Pasteur published an account of the bacteriology of swine erysipelas; this was the beginning of an active period with discovery crowding on discovery. In 1883 came Koch's announcement of the comma bacillus as the cause of cholera; in 1884 Löffler's description of the bacillus of diphtheria and Nicolaier's discovery of the bacillus of tetanus. So the march of discovery continued until the roll of diseases of known etiology in a short time included typhoid fever, pneumonia, meningitis, influenza, bubonic plague and the various surgical suppurations.
The rapid discoveries of disease-producing microorganisms established definitely Pasteur's doctrine of specificity as applied to etiology and led at once to an interest in public health measures which increased as the years passed, until now it has become one of the most vital interests of our social system. Even in the early eighties, with a knowledge of the etiology and mode of transmission of a few diseases and of Lister's results in antiseptic surgery, it was possible to postulate general prophylactic measures safeguarding the individual and the community, and as knowledge of etiology and transmission increased, so did prophylaxis. Hygeia was again enthroned and it was recognized that "an ounce of prevention is worth a pound of cure."
But prophylaxis was not entirely satisfying. If a specific etiology, why not a specific therapy for bacterial diseases? Men remembered inoculation for smallpox introduced into England by Lady Mary Wortley Montagu early in the eighteenth century. This procedure, the inoculation of healthy individuals with material from the pustules of those ill with a mild form of smallpox had materially reduced the fatality of the disease. The procedure, it is true, had been made illegal in England in 1840, because of the greater success and less danger of Jenner's wonderful discovery (1798) of vaccination with the fluid of the pustule of cowpox. Inoculation, however, despite the fact that it sometimes caused severe and fatal cases of smallpox and perpetuated foci for the dissemination of the disease, had demonstrated that the mild inoculation disease visually protected against the more severe forms. That
