In 1905 two different etiologic agents for syphilis were proposed in Berlin, one, the Cytorrhyctes luis, by John Siegel, the other, Spirochaete pallida, by Fritz Schaudinn. Both scientists were pupils of Franz Eilhard Schulze, and were outsiders to the Berlin medical establishment. Both belonged to the same thought collective, used the same thought style, and started from the same supposition that the etiologic agent of syphilis must be a protist. Both used the same morphological approach, the same microscopes and the (...) same stains. Both presented their findings in the same societies, used the same rhetoric, published in the same journals, used the same arguments to criticise each other's shortcomings. Both were backed by powerful institutions and enlisted the support of prestigious patrons. Within half a year, the scientific community at large had in its overwhelming majority accepted Schaudinn's results and rejected those of Siegel. Social forces thus cannot be shown to have played any role in deciding the issue. Ludwik Fleck's suggestion that 'appropriate influence' and a 'proper measure of publicity throughout the thought collective' would have been sufficient for Siegel's ideas to win the day is untenable. (shrink)

After the louse transmission of epidemic typhus had been established (1909), a small microorganism (thought to belong to a new genus, Rickettsia) was shown in enormous numbers in the guts of lice that had fed on human typhus victims. Attempts at cultivating this organism on inert media failed; tansfer from louse to louse without loss of virulence for the vertebrate host was successful. Some scientists were not convinced of the etiologic role of Rickettsiae, because the presence of this microbe in (...) blood and organs of victims or of experimentally infected animals was difficult to demonstrate. This uncertainty was dispelled in 1928, when in guinea pigs infected with material from the closely related disease Tabardillo (murine typhus) abundant Rickettsiae were revealed in the tunica vaginalis. Live vaccines, derived from strains of murine typhus and deployed in French North Africa, were considered by outside observers as unsafe. Killed vaccines were derived from the masses of Rickettsiae present in louse guts, in chick embryo yolk sacs or in vertebrate lungs. These developments were not spurned by any 'upswing of virology' but by the threat of typhus in endemic areas and, after 1938, in a war-torn world. Their basis was firmly anchored in bacteriological thought styles and techniques. (shrink)