57 2 Bubonic Plague 



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 

 the description given by Yersin is the more correct of the 

 two. 



In the "Japan 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 Yersin'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. 



Cultivation. When cultures are made from the blood 

 or softened contents of the buboes, the bacillus may be 

 obtained in pure culture, and develops well upon artificial 

 culture media. 



Bouillon. In bouillon, a diffuse cloudiness was ob- 

 served by Kitasato, though Yersin observed that the cul- 

 tures resembled erysipelas cocci, and contained zooglea 

 attached to the sides and at the bottom of the tube of 

 nearly clear fluid. 



Haffkine * found that when an inoculated bouillon cul- 

 ture is allowed to stand perfectly at rest, on a firm shelf 

 or table, a characteristic appearance develops. In from 

 twenty-four to forty-eight hours, the liquid remaining limpid, 

 flakes appear underneath the surface, forming little islands 

 of growth, which in the next twenty-four to forty-eight 

 hours grow into a jungle of long stalactite-like masses, the 

 liquid remaining clear. In from four to six days these 

 islands become still more compact. If the vessels be dis- 

 turbed, they fall like snow and are deposited at the bottom, 

 leaving the liquid clear. 



Colonies. Upon gelatin plates at 22 C. the colonies may 

 be observed in twenty-four hours by the naked eye. They 

 are pure white or yellowish-white, spheric when deep in the 

 gelatin, flat when upon the surface, and are about the size 

 of a pin's head. The gelatin is not liquefied. Upon micro- 

 scopic examination the borders of the colonies are found to 

 be sharply defined. The contents become more granular as 

 *"Brit. Med. Jour.," June 12, 1897, p. 1461. 



