BACILLUS PESTIS BUBONIC^ 



THE Bacillus Pestis Bubonicae was discovered by 

 Kitasato in 1894, and independently by Yersin a 

 little later. It is found in almost pure culture in 

 the buboes characteristic of the disease, and it is 

 also widely spread, though not in large numbers, in 

 the internal organs, and is found in the blood, lymph, 

 urine, and faeces of those affected. 



The bacillus is undoubtedly the cause of the 

 disease, though the various methods by which the 

 organism gains access to the body are not fully 

 known ; subcutaneous inoculation (wounds, &c.) is 

 certainly one of them. Animals are affected by the 

 disease, and many observers (Koch, &c.) think that 

 it is primarily a disease of the rat. 



Preparations made with material from the bubo, 

 or from the spleen or liver of an infected rat 

 (Fig. 91) show the bacillus in large numbers. It is 

 short, thick, round-ended, and, owing to its tendency 

 to stain more deeply at the extremities than in the 



