[The traveling laboratory: Robert Koch investigates cholera 1883/84]

Based on the example of Robert Koch's cholera expedition of 1883/84, this paper analyses travelling as a mode of doing research that was characteristic of an applied science such as hygiene. A laboratory for hygiene is dependent on a certain environment which becomes noticeable through its absence. Examples are its dependence on the cultural acceptance of pathological dissections or a suitable climate in which gelatine-based solid culture media do not liquefy. Travelling abroad gave Koch and his collaborators privileged access to the public at home. Laboratory work was given the heroic image of a crusade against epidemics, and what had been complex research was presented as a simple discovery. Travelling abroad fulfilled Koch's own youthful ambitions and simultaneously opened up his career as a figure of public life. In addition it provided him with the experience of doing science in a profitable and enjoyable way.