NON-PATHOGENIC .BACTERIA. 271 



Bacillus Mesentericus Vulgatus (Potato bacillus).— Found 

 on potatoes; common in earth; a large, long rod with rounded 

 ends, often forming long chains; motile; it is stained by Gram's 

 method; liquefies gelatin; aerobic; forms spores; grows rap- 

 idly, best at about 20° C; grows on ordinary media, forming 

 on potato a thin, wrinkled membrane which spreads rapidly 

 over the surface. It coagulates milk, redissolving the coag- 

 ulum. It possesses numerous flagella. The spores are ex- 

 tremely resistant to heat. 



Bacillus Phosphorescens Indicus. — Obtained from sea- 

 water; a small, thick, rod-shaped bacillus with rounded ends, 

 also forming threads; actively motile; not stained by Gram's 

 method; liquefies gelatin; aerobic. It grows slowly, best be- 

 tween 20° and 30° C., upon the usual media, except milk and 

 potato. Its culture, when old, especially when on animal 

 nutrient-media and in the presence of certain sodium salts, 

 are phosphorescent in the dark. 



There are various other bacilli which produce phosphores- 

 cence, some of which do not liquefy gelatin. 



Bacillus Mycoides (Bacillus ramosus; Wurzelbacillus) .— 

 Found in the earth and in water; very common; a large, short 

 bacillus with rounded ends, often forming chains and threads; 

 slightly motile; liquefies gelatin; aerobic forms centrally lo- 

 cated, oval spores; grows rapidly at room and incubator tem- 

 peratures upon the usual media. It is said rapidly to decom- 

 pose albumin with the formation of ammonia. 



Bacillus Subtilis (Hay bacillus). — ^Found on hay, in the 

 air, water, ground and decomposing fluids; very common; 

 a large bacillus somewhat resembling the anthrax bacillus in 

 form, with rounded ends, often forming chains or long fila- 

 ments; motile; possessing flagella; liquefies gelatin; aerobic; 

 it is stained by Gram's method. It may have large, centrally 

 located spores, which form best on potato at about 30° C. 

 The spores are extremely resistant to heat and to chemical 



