It is certain that a disease, or possibly more than one disease, of this nature is a source of serious loss to the live stock industry in the United States, and there can no longer be any doubt that a considerable part of this loss is due to the definite specific disease prevalent on the continent of Europe and in England, and known as Contagious, Infectious, or Epizoötic Abortion. The purpose of this bulletin is the brief presentation of some of the facts concerning the cause, prevention and restriction of this disease, which have been established by modern investigation, for the information of men engaged in live stock production. BACTERIOLOGICAL INVESTIGATIONS ELSEWHERE Nocard carried out the first extensive bacteriological investigation of contagious abortion. In microscopic preparations of the diseased placenta he was able to recognize numerous short bacilli and micrococci. These were also found in the amniotic fluid. He obtained pure cultures of these two organisms, but failed to induce abortion upon inoculating these cultures into other animals. Neither of the germs obtained in culture could therefore be regarded as the causative agent in the disease. In 1895 Bang and Stribolt undertook the investigation of this disease, and their results are now generally regarded as the most important of all the contributions to the study of this subject. A cow showing all the symptoms of impending abortion was purchased and slaughtered. The unopened uterus was removed to the laboratory where it was opened with special precautions to avoid all contamination. An abundant, grayish yellow, odorless exudate was found between the ovum and the inner wall of the uterus. Upon standing this exudate separated into two layers, a reddish yellow serum above, and a grayish yellow partly solid layer below. In microscopic preparations of this exudate, stained with Loeffler's methylene blue, numerous very small bacilli were found, apparently in pure culture, some of them lying free, but large numbers of them crowded together inside cells. These latter appeared at first to be micrococci, but more careful examination proved them to be really short rods. Bang and Stribolt were able to cultivate this organism in tubes of a gelatin-agar-serum medium, the germ developing only in a particular zone beginning about 5 mm. beneath the surface of the medium and extending downward 10 to 15 mm. After considerable work with cultures, they concluded that the bacillus is neither an aerobe nor an anaerobe, in the ordinary sense, but exhibits a very peculiar behavior in respect to oxygen, requiring for its development a partial pressure of oxygen somewhat less than that present in the atmosphere. They were unable to obtain growth of the germ in the presence of the ordinary atmosphere, nor in the absence of oxygen (Pyrogallol method). Curiously enough, by placing their tube cultures in an atmosphere of pure oxygen,