1882 · Stained Bacilli Under Microscopes · Work 1006 of 1,871
A room of the physiological institute in Berlin on a March evening, gas lamps in warm yellow light, along the wall a table in green baize with a row of brass microscopes, each with a glass slide bearing a pale brown smear with fine blue specks, listeners in black frock coats seen from directly behind, faces turned fully away, one bent to an eyepiece, at the end of the table the man, a man of thirty-eight with a full dark beard and round wire spectacles, in a dark frock coat, one hand tilting the mirror of a microscope.
Who
Robert Koch (1843–1910) was one of the founders of bacteriology. Born on 11 December 1843 in Clausthal in the Harz mountains, the son of a mining official, he studied medicine at Göttingen and from 1872 to 1880 was district medical officer in Wollstein in the Prussian province of Posen. There, in the flat that also served as his laboratory, he proved that a particular bacterium causes anthrax. In 1880 the Imperial Health Office brought him to Berlin. In 1882 he found the cause of tuberculosis, and in 1883, on an expedition to Egypt, the cause of cholera. In 1891 he became director of the new Institute for Infectious Diseases, today's Robert Koch Institute, and in 1905 he received the Nobel Prize in Medicine. His methods of growing bacteria in pure culture, staining and photographing them still shape microbiology. There is a darker side: on an expedition to East Africa in 1906–07 he doubled the dose of the arsenic compound Atoxyl against sleeping sickness, although he knew the risks; many patients suffered pain and colic, some went blind. The Robert Koch Institute today calls this work ethically unacceptable. Koch died in Baden-Baden on 27 May 1910.
The moment
On the evening of 24 March 1882 Koch addressed the Physiological Society of Berlin at the Institute of Physiology headed by Emil du Bois-Reymond. One or two dozen listeners had been expected; more than a hundred came, and many had to stand behind the rows of chairs. Koch was no stirring speaker. His subject was the disease that, as his printed text records, killed one in seven people. He had found a stain that made its cause visible: first methylene blue, then a brown dye called vesuvin. Under the microscope the tissue appeared brown and the tubercle bacteria blue. After the talk everyone could look for themselves: his assistants had set up a row of microscopes in the hall. When Koch had finished speaking, the room fell silent; there was no applause. Paul Ehrlich later called the evening his single greatest scientific experience. The picture looks along the row of microscopes to Koch at its end, adjusting the mirror of one instrument. The lecture appeared in print on 10 April 1882.
The other side
The evening made Koch famous almost overnight, and in June 1882 he was promoted to Privy Government Councillor. With fame came the pressure to deliver a cure as well. In August 1890, at the International Medical Congress in Berlin, he announced a remedy for tuberculosis, later called tuberculin, and kept its composition secret. Koch expected it to earn several million marks a year. On humans he had first tested it only on himself and on his 17-year-old mistress. In early 1891 reports of patients getting worse, and of deaths, piled up; as a cure, tuberculin had failed. It remained useful only for diagnosis.
What the sources leave open: What the hall looked like, how many microscopes of which make stood there and how it was lit is not recorded; room, gas light and table are typified. The assistants at the microscopes are not known by name, and whether Koch himself stood by the row is not documented. His face follows a photograph from 1890, made younger and with a darker beard for 1882.