Robert Koch
On 24 March 1882, Robert Koch told the Physiological Society of Berlin that he had found the cause of tuberculosis: a single slow-growing bacillus, made visible by a new stain, grown in pure culture, and proved by inoculation. This edition reproduces his announcement in the original German, exactly as his first readers met it, with editorial apparatus supplied for the modern reader. Koch’s 1882 paper landed in the middle of the most consequential reorientation in the history of medicine: the passage from the ancient idea that disease arises from bad air, imbalance, or spontaneous corruption to the modern understanding that specific living microorganisms cause specific infectious diseases. For most of the nineteenth century, tuberculosis was attributed to heredity, constitution, climate, or moral and social circumstance. It was the leading cause of death in the industrializing world, and it was widely held not to be contagious at all. Against that background, the claim that tuberculosis was an infection caused by a particular germ was not a refinement of existing belief but a frontal challenge to it.
