[Knowledge on Loose Sheets in the Context of fixed Theories. Theodor Leber's Research of Inflammation]

At the end of the nineteenth century, after twelve years of intensive research, the ophthalmologist Theodor Leber (1840-1917) established the chemotaxis of leukocytes as part of inflammation research. Although at the time his theory was smoothly enlisted into immunological research, up until now his name has been connected to chemotaxis only in the English-language literature. Leber was able to use his experimental system to develop a theory of the chemical attraction of the leukocytes during inflammation processes by the beginning of the 1880s, but his unconventional methodology-introducing chemically neutral contaminants in order to trigger inflammation in the eyes of rabbits-contradicted the basic bacteriological Denkstil (style of thought) of inflammation research at the time. Leber held fast to his research practice, which consisted of closely interlocking experimental and theoretical work. Only when an opening appeared in the bacteriological Denkstil was Leber able to transform his experimental observations, written on loose sheets of paper, into convincing evidence for his theory of inflammation. This micro-historical reconstruction of Leber's experimental and written work, based on his original lab protocols, opens up the research practice of a scientist who was not recognized by the established microbiological inflammation research of the time. Moreover, persistent factors in the generation of knowledge are revealed by connecting this micro-historical reconstruction with a macro-history analysis. Indeed Leber developed his specific paper technology in order to mobilise and stabilise the scientific findings gained through experiment because of the persistence of the bacteriological Denkstil.