Editing Paul Ehrlich (section)

====Friendship with Robert Koch====
[[File:Robert Koch.jpg|thumb|left|[[Robert Koch]], around 1900]]

When a student in Breslau, Ehrlich was given an opportunity by the pathologist Julius Friedrich Cohnheim to conduct extensive research and was also introduced to [[Robert Koch]], who was at the time a district physician in Wollstein, Posen Province. In his spare time, Koch had clarified the life cycle of the [[anthrax]] pathogen and had contacted [[Ferdinand Cohn]], who was quickly convinced by Koch's work and introduced him to his Breslau colleagues. From 30 April to 2 May 1876, Koch presented his investigations in Breslau, which the student Ehrlich was able to attend.

On 24 March 1882, Ehrlich was present when Koch, working since 1880 at the Imperial Public Health Office (''Kaiserliches Gesundheitsamt'') in Berlin, presented the lecture in which he reported how he was able to identify the [[Mycobacterium tuberculosis|tuberculosis pathogen]]. Ehrlich later described this lecture as his "greatest experience in science". The day after Koch's lecture, Ehrlich had already made an improvement to Koch's staining method, which Koch unreservedly welcomed. From this date on, the two men were bound in friendship.

In 1887 Ehrlich became an unsalaried lecturer in internal medicine (''[[Privatdozent]] für Innere Medizin'') at Berlin University, and in 1890 took over the tuberculosis station at a public hospital in Berlin-Moabit at Koch's request. This was where Koch's hoped-for tuberculosis therapeutic agent [[tuberculin]] was under study; and Ehrlich had even injected himself with it. In the ensuing [[Tuberculin#The tuberculin scandal|tuberculin scandal]], Ehrlich tried to support Koch and stressed the value of tuberculin for diagnostic purposes. In 1891 Koch invited Ehrlich to work at the newly founded  ''Institut für Infektionskrankheiten'' (Institute of Infectious Diseases, which became the [[Robert Koch Institute]])<ref>[http://www.rki.de/EN/Content/Institute/History/history_node_en.html The Robert Koch Institute]. rki.de</ref> at ''Friedrich-Wilhelms-Universität'' ([[Humboldt University]]) in Berlin. Koch was unable to give him any remuneration, but did offer him full access to laboratory staff, patients, chemicals and laboratory animals, which Ehrlich always remembered with gratitude.