THE BACTERIA OF THE HEMORRHAGIC SEPTICEMIAS 317 



mammals and birds. The virulence is variable and seems to be 

 especially developed for the species of animal in which the organ- 

 ism is found. It does not differ essentially from B. avisepticus. 

 Other minute bacteria exhibiting the same general characteristics 

 and occurring as a generalized infection in diseases of animals 

 are Bacillus murisepticus in mice and Bacillus (Bacterium) rhusio- 

 pathicz suis in swine. 



Bacillus (Bacterium) Pestis. This organism was discovered 

 simultaneously by Kitasato and Yersin in 1894 in the bodies of 

 persons dying of bubonic plague in the epidemic at Hongkong. 



FIG. 129. Bacillus of bubonic plague. (Yersin.} 



The description of Yersin has proven to be the more accurate. 

 The organism is unquestionably the cause of plague, as in addi- 

 tion to the evidence of animal experimentation there are several 

 instances of fatal infection of men working with the organism 

 in laboratories far removed from any focus of the disease, and 

 finally the very unfortunate accident at Manila 1 where cholera 

 vaccine mixed with a culture of B. peslis by mistake was injected 

 into men and caused fatal bubonic plague. 



B. pestis in the body of the patient is a short plump rod, 0.5 

 to 0.7;* wide by 1.5 to i.8/z long, and rounded at the ends. When 



1 Freer: Journ. A. M. A., 1907, Vol. XL VIII, pp. 1264-65. 



