Botulinum toxin
In 1895 (seventy-five years later), Émile van Ermengem, professor of bacteriology and a student of Robert Koch, correctly described "Clostridium botulinum" as the bacterial source of the toxin. Thirty-four attendees at a funeral were poisoned by eating partially salted ham, an extract of which was found to cause botulism-like paralysis in laboratory animals. Van Ermengem isolated and grew the bacterium, and described its toxin, which was later purified by P Tessmer Snipe and Hermann Sommer.
Pierre Paul Émile Roux
Also in 1883, Roux published, with Alexandre Yersin, the first of his classical works on the causation of diphtheria by the Klebs-Loeffler bacillus, then an extremely prevalent and lethal disease, particularly among children. He studied its toxin and its properties, and began in 1891 to develop an effective serum to treat the disease, following the demonstration, by Emil Adolf von Behring (1854–1917) and Kitasato Shibasaburō (1852–1931) that antibodies against the diphtheric toxin could be produced in animals. He successfully demonstrated the use of this antitoxin with Auguste Chaillou in a study with 300 diseased children in the Hôpital des Enfants-Malades and was henceforth hailed as a scientific hero in medical congresses throughout Europe.