584 Plague 



Yersin rather than that of Kitasato, and it is certain that 

 the description given by Yersin is the more correct of the 

 two. 



In the "J a P an Times," Tokio, November 28, 1899, Kita- 

 sato 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 Yer sin's observation that the bacilli first 

 multiply in the lymphatics. 



Both Kitasato and Yersin showed that in blood drawn 

 from the finger-tips and in the softened contents of the 

 glands the bacillus may be demonstrable. 



Fig. 202. Bacillus of bubonic plague (Yersin). 



Morphology. The bacillus is quite variable. Usually it 

 is short and thick a "coco-bacillus," as some call it 

 with rounded ends. Its size is small (1.5 to 2 ^ in length) 

 and 0.5 to 0.75 ^ in breadth. It not infrequently occurs in 

 chains of four or six or even more, and is occasionally en- 

 capsulated. It shows active Brownian movements, which 

 probably led Kitasato to consider it motile. Yersin did not 

 regard it as motile, and was correct. Gordon* claims that 

 some of the bacilli have flagella. No spores are formed. 



Staining. It stains by the usual methods; not by 

 Gram's method. When stained, the organism rarely 



* "Centralbl. f. Bakt. u. Parasitenk.," June 24, 1897, Bd. xxi, Nos. 

 20 and 2 1 . 



