Specific Organism 545 



Plague," finds it convenient to divide plague into (a) bubonic or 

 ganglionic, (b) septicemic, and (c) pneumonic forms. Of these, 

 the bubonic form is most frequent and the pneumonic form most 

 fatal. 



Specific Organism. The bacillus of bubonic plague was inde- 

 pendently discovered by Yersin* and Kitasatof in the summer of 

 1894, during an epidemic of the plague then raging at Hongkong. 

 There seems to be little doubt but that the micro-organisms de- 

 scribed by the two observers are identical. 



OgataJ states that while Kitasato found the bacillus in the 

 blood of cadavers, Yersin seldom found it in the blood, but always 

 in the enlarged lymphatic glands; that Kitasato's bacillus retains 

 the color when stained by Gram's method; Yersin's does not; that 

 Kitasato's bacillus is motile; Yersin's non-motile; that the colonies 

 of Kitasato's bacillus, when grown upon agar, are round, irregular, 



Fig. 225. Bacillus of bubonic plague (Yersin). 



grayish white, with a bluish tint, and resemble glass-wool when 

 slightly magnified; those of Yersin's bacillus, white and transparent, 

 with iridescent edges. Ogata, in his investigations, found that 

 the bacillus corresponded with the description of Yersin rather than 

 that of Kitasato, and it is certain that of the two the description 

 given by Yersin is the more correct. 



In the "Japan Times," Tokio, November 28, 1899, Kitasato 

 explains that, his investigations being made upon cadavers that 

 were partly putrefied, he was led to believe that the bacillus first 

 invaded the blood. Later studies upon living subjects showed him 

 the error of this view and the correctness of Yersin's observation 

 that the bacilli first multiply in the lymphatics. 



Both Kitasato and Yersin showed that in blood drawn from the 



* "Ann. de PInst. Pasteur," 1894, 9. 



t Preliminary notice to the bacillus of bubonic plague, Hongkong, July 7, 1894. 

 j " Centralbl. f. Bakt. u. Parasitenk.," Sept. 6, 1897, Bd. xxii, Nos. 6 and 7, P. 

 170. 



35 



