Louis Pasteur
Initial errors

Arriving in Alès, Pasteur familiarized himself with pébrine and also with another disease of the silkworm, known earlier than pebrine: flacherie or dead-flat disease. Contrary, for example, to Quatrefages, who coined the new word pébrine, Pasteur made the mistake of believing that the two diseases were the same and even that most of the diseases of silkworms known up to that time were identical with each other and with pébrine. It was in letters of 30 April and 21 May 1867 to Dumas that he first made the distinction between pébrine and flacherie.

He made another mistake: he began by denying the "parasitic" (microbial) nature of pébrine, which several scholars (notably Antoine Béchamp) considered well established. Even a note published on 27 August 1866 by Balbiani, which Pasteur at first seemed to welcome favourably had no effect, at least immediately. "Pasteur is mistaken. He would only change his mind in the course of 1867".
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