Contributiona. Reported discovery of the tuberculosis bacillus.
NotesNotes from various sources: Key factors in Koch's success were the use of Abbe's contributions to microscopy and the staining (methylene blue) technique developed by Ehrlich. More rigorous than earlier anthrax work. Often considered first real proof of a specific human disease being caused by a specific bacterium. (Publication of "postulates" came later, in 1884.) Reported as a lecture-demonstration (in March, at Berlin Physiol. Soc. rather than Berlin Med. Soc. because of Virchow's dominance and lack of sympathy for the young germ-theory advocates; and as a publication (in April). The lecture, published only three weeks after it was given, became a famous success. According to Loeffler's account (quoted by Brock) Koch counterstained his preparations with vesuvin (Bismark Brown) for purposes of photography. When histological sections of diseased tissue were photographed under blue light, the brown-stained tissue absorbed the light and appeared dark on the photographic negative. The blue-stained bacilli appeared bright and transparent on the negative. Koch thus succeeded in enhancing contrast in photographs; but was surprised to find that when the stained sections were observed directly in the microscope, the bacilli were still blue, despite the counterstain. Brock records that the illustrations (drawings, not photographs) in Koch's publication were chromolithographs, in which the tissues were colored brown and the bacilli blue -- but apparently this refers to Koch's final paper on the etiology of TB, published in 1884.
Pathogen ClassBacteria

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