Editing Robert Koch (section)

===Tuberculosis===
[[File:Aetiologie der Tuberkulose.jpg|thumb|Koch's drawing of tuberculosis bacilli in 1882 (from ''Die Ätiologie der Tuberkulose'')]]
During his time as the government advisor with the Imperial Health Agency in Berlin in the 1880s, Koch became interested in [[tuberculosis]] research. At the time, it was widely believed that tuberculosis was an inherited disease. However, Koch was convinced that the disease was caused by a bacterium and was infectious. In 1882, he published his findings on tuberculosis, in which he reported the causative agent of the disease to be the slow-growing ''[[Mycobacterium tuberculosis]]''.<ref name="Brock Biology of Microorganisms" /> He published the discovery as "''Die Ätiologie der Tuberkulose''" (''The Etiology of Tuberculosis''),<ref name=":5" /> and presented before the German Physiological Society at Berlin on 24 March 1882. Koch said,<blockquote>When the cover-glasses were exposed to this staining fluid [methylene blue mixed with [[potassium hydroxide]]] for 24 hours, very fine rod-like forms became apparent in the tubercular mass for the first time, having, as further observations showed, the power of multiplication and of spore formation and hence belonging to the same group of organisms as the anthrax bacillus... Microscopic examination then showed that only the previously blue-stained cell nuclei and detritus became brown, while the tubercle bacilli remained a beautiful blue.<ref name=":2" /><ref name=":3" /></blockquote>

There was no particular reaction to this announcement. Eminent scientists such as [[Rudolf Virchow]] remained sceptical. Virchow clung to his theory that all diseases are due to faulty cellular activities.<ref name=":12">{{Cite journal|last1=Kaufmann|first1=Stefan H. E.|last2=Schaible|first2=Ulrich E.|date=2005|title=100th anniversary of Robert Koch's Nobel Prize for the discovery of the tubercle bacillus|url=https://pubmed.ncbi.nlm.nih.gov/16112578|journal=Trends in Microbiology|volume=13|issue=10|pages=469–475|doi=10.1016/j.tim.2005.08.003|pmid=16112578}}</ref> On the other hand, [[Paul Ehrlich]] later recollected that this moment was his "single greatest scientific experience."<ref name=":9" /> Koch expanded the report and published it under the same title as a booklet in 1884, in which he concluded that the discovery of tuberculosis bacterium fulfilled the three principles, eventually known as Koch's [[postulates]], which were formulated by his assistant Friedrich Loeffler in 1883, saying:<blockquote>All these factors together allow me to conclude that the bacilli present in the tuberculous lesions do not only accompany tuberculosis, but rather cause it. These bacilli are the true agents of tuberculosis.<ref name=":12" /></blockquote>