Abstract

Christian Gottfried Ehrenberg (1795–1876) researched living and fossil microbes (infusoria) from air, sediment or food samples. His discovery around 1840 that infusoria thriving in the Berlin underground would damage buildings caused an early microbe scare in public. Around 1848, Ehrenberg devoted his attention to ‘blood’ prodigies associated with the cholera, the basis of which he identified as an innocuous red microbe. Both cases allow us to grasp the goals of Ehrenberg’s natural history of microbes: following up on Alexander von Humboldt, he aimed at a full picture of microbes’ place in nature, such as in biological and geological processes, as well as for humans. What is more, understanding the context of his investigations in a time of political instability reveals a dimension of this story beyond historiography of microbiology: Ehrenberg’s conservative-reformist perspective on materialism, religion and the state sheds new light on the relationship of science and politics in Prussia around 1848. Not least, Ehrenberg’s mid-19th century arguments about the omnipresence and impact of microscopic life resonates with contemporary ecological debates about microbes’ effects on geology or the climate.