cavities of the body previously closed on account of the great mortality due to sepsis. Antisepsis shares with anesthesia, as its discoverer, Lister, shares with Morton, Warren and Simpson, the honor of the great advances surgery has made in the treatment of disease and injuries of the abdomen, thorax and the cranial cavity. Who can compute the relief from suffering and the saving of life which may be traced through Lister to Pasteur's laboratory experiments on fermentation?
The recognition of the principle of asepsis by the surgeons was, then, as we have seen, slow and grudging enough; among the profession at large the theory of infection as applied to acute diseases gained more slowly still. It was not until 1880 that advance in the knowledge of the bacterial etiology of infectious diseases assumed such definite shape as to attract general attention. As we look back upon this early work we see clearly that one reason for this slow advance was the absence of proper methods of isolating bacteria in what we now call pure cultures. Pasteur and his co-laborers made (1) direct search for bacteria in the secretions, blood or tissue juices, or (2) inoculated fluid media or animals with such material. By the first of these methods it was possible to recognize bacteria if they were especially abundant, as in anthrax, and it was by this method that Neisser discovered the gonococcus (1879) and Hansen the leprosy bacillus (1879), bacteria which are particularly abundant in the local lesions of the respective diseases. The second method, the use of fluid media, was satisfactory if the material for study contained only one type of organism; if more than one it was obviously difficult to study the life history of a bacterium or to obtain exact results by the inoculation on account of the simultaneous growth of associated or contaminating organisms. This difficulty was overcome by Koch, in 1881, through the introduction of solid culture media. Koch had already, while a country practitioner, definitely and clearly established the relation of the anthrax bacillus to the splenic fever of cattle and had demonstrated in this organism the formation of spores and their importance; also he had published most important observations on the bacteriology of wound infection. The use of solid media, which it is said was suggested to Koch by the growth of mould on potato, led at once to rapid advance, for as each bacterium placed on a solid medium causes, as it multiplies, the growth of a visible colony, it was possible to distinguish colonies having different characteristics and by transplantation to secure pure cultures. The demonstration of Koch's solid media and plate method at the Congress of Hygiene in London in 1881 caused Pasteur to exclaim "C'est un grand progrés." This advance and the use of microscopes equipped with the oil immersion lens and the Abbe condenser, and the increased knowledge concerning the use of the aniline dyes for staining purposes gave