北里柴三郎
There, in a small hut (according to "Plague" by Wendy Orent) since he was denied access to British hospitals at his arrival, he made his greatest discovery: that of the pathogen which causes the disease. Dr Kitasato Shibasaburō, also in Hong Kong, had identified a bacterium several days earlier. There is controversy whether this was the same pneumococci or a mix of the two. Because Kitasato's initial reports were vague and somewhat contradictory, some give Yersin sole credit for the discovery. However, a 1976 thorough analysis of the morphology of the organism discovered by Kitasato determined that "we are confident that Kitasato had examined the plague bacillus in Hong Kong in late June and early July 1894", only days after Yersin announced his own discovery on 20 June, and that Kitasato "should not be denied this credit". The plague bacillus develops better at lower temperatures, so Yersin's less well-equipped lab turned out to be an advantage in the race with Kitasato, who used an incubator. Therefore, although at first named “Kitasato-Yersin bacillus” by the scientific community, the microbe will later assume only the latter's name because of the one identified by Kitasato, a type of streptococcus, cannot be found in the lymphatic glands. Yersin was also able to demonstrate for the first time that the same bacillus was present in the rodent as well as in the human disease, thus underlining the possible means of transmission. This important discovery was communicated to the French Academy of Sciences in the same year, by his colleague Emile Duclaux, in a classic paper titled "La peste bubonique à Hong-Kong".