BACILLUS MURISEPTICUS. 329 



may be taken for a diplococcus. It is not motile, has no 

 flagella, and does not form spores. It stains well with the 

 usual dyes, and sometimes exhibits slight polar staining. 

 Gram's stain is not applicable. It is feebly resistant to heat 

 and desiccation. It is a facultative anaerobe. 



Its growth in culture -media resembles the cultures of the 

 hog-cholera bacillus. No growth forms on potato unless it is 

 alkaline, when a very thin grayish film is seen to develop. It 

 produces a very slight amount of acid, not sufficient to coagu- 

 late milk nor to discolor litmus solution. 



It is pathogenic for animals only. 



Bacillus Typhi Murium. 



This is a very small, short germ, which in culture often 

 forms very long filaments. It varies greatly in thickness. 

 It is not motile, although it possesses numerous flagella. It 

 does not form spores ; stains well with Loeffler's alkaline 

 methylene-blue ; it is a facultative anaerobe. 



Plate colonies on gelatin are at first grayish, but soon turn a 

 yellowish-brown. In the gelatin stab a grayish-white growth 

 is formed on the surface of the medium, with an almost imper- 

 ceptible growth along the track of the needle. When grown 

 in milk, acid is produced, but the milk is not coagulated. 



The germ is intensely pathogenic for mice. It can be iso- 

 lated from the blood and lymph-channels. It has been used 

 with remarkable success in freeing infested houses from 

 mice by saturating bread with a bouillon culture of the 

 bacillus. The bread is pushed into the mouse-holes at a time 

 of the year when food is not plentiful. The mice which are 

 infected in this way die rapidly, and their dead bodies are 

 eaten by other mice, which also succumb to the disease. In 

 this way the premises can be rid of the pests in a very short 

 time, usually in about ten or twelve days. 



Bacillus Murisepticus (Mouse Septicaemia). 



Bacillus murisepticus resembles an organism found in the 

 lesions of swine erysipelas so closely that these two germs are 

 considered by many as identical. They are very small, about 



