The third pandemic of plague started just before the ‘Golden Era’ of bacteriology when Robert Koch and Louis Pasteur formulated the basic principles and methods for identification of the causative organism of infectious diseases. The time was ripe for isolation of the plague bacterium and when the disease struck Hong Kong in May 1894, Alexandre Yersin and Shibasaburo Kitasato both actively sought to identify ‘the bacterium of bubonic plague’. By late June/early July of the same year both investigators announced isolation and identification of the plague bacillus (Kitasato, 1894; Yersin, 1894). On this first correlation of Yersinia pestis (then named Bacterium pestis) with plague, production of capsule by the bacterium was already recognised. While there is some doubt as to the identity of Kitasato’s final isolate (Bibel and Chen, 1976; Butler, 1983) both he and Yersin undoubtedly repeatedly observed the characteristic bilobed staining, encapsulated Y. pestis (Figure 1a) from buboes of plague victims.