NON-PATHOGENIC BACTERIA. 223 



in decomposing vegetable material and in the stomachs of 

 ruminant animals; a large, thick rod with round ends, often 

 arranged in chains; actively motile; anaerobic; forms spores 

 which are located in the center of the bacillus and give it a 

 spindle-shaped form, or at one end, when it has the outline 

 of a tadpole; has not been cultivated satisfactorily on ordinary 

 media; grows best at 35" to 40° C; decomposes carbohy- 

 drates with the formation of butyric acid; decomposes cel- 

 lulose. Organisms of similar form have been found as fossils 

 belonging to the carboniferous period. 



Bacillus butyricus (Hueppe). — Found in milk; appears as 

 a small, irregular rod, also forming threads; very actively 

 motile; aerobic; rapidly liquefies gelatin; forms centrally 

 located spores; grows best at 35° to 40° C; grows rapidly 

 on ordinary media; coagulates milk, redissolving the coagulum, 

 producing also butyric acid. A large number of bacteria, both 

 aerobic and anaerobic, produce butyric acid fermentation. 



Bacillus megaterium. — Obtained by de Bary from cooked 

 cabbage-leaves; common on plants and earth; a large bacillus 

 with rounded ends, often forming chains; motile; slowly lique- 

 fies gelatin; aerobic; forms spores, especially in potato cul- 

 tures; grows rapidly at room temperature on the ordinary 

 media. 



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; hquefies 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. 



