ABSTRACT
Human tuberculosis is one of the chief causes of premature death, of chronic invalidism, and of social dependence in survivors of its victims. Microscopic investigations of tuberculosis began about 1840, and in 1847 Virchow buttressed the dualist theory by teaching that caseation is not peculiar to tuberculosis. Sanderson gave experimental evidence which was inconsistent with experiments made by others appearing to show that tuberculosis might result from inoculation of nontuberculous material. Experiments on animals have shown that tuberculosis can be communicated, not only by its inoculation, but also by inhalation or by ingestion. Theobald Smith showed that the tubercle bacilli of bovine origin are thicker, shorter and more regular in shape than tubercle bacilli of human origin, also that they are dysgonic, i.e., show a scantier growth on various media than do the human type, which are hence called eugonic.
