224 



MANUAL OF BACTERIOLOGY. 



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 cultures, when old, especially when on afi'^^ 

 mal nutrient-media and in the presence of certain sodium 

 salts, are phosphorescent in the dark. 



There are various other bacilK which produce phosphores- 

 cence, some of which do not liquefy gelatin. 



Fig. 54. — BAciLLtis Sxtetilis. (X 1000.) 



Bacillus mycoides (Bacillus ramosus; WurzelbaciUus).-^ 

 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 cen- 

 trally located, oval spores; grows rapidly at room and incu- 

 bator temperatures upon the usual media. It is said rapidly 

 to decompose albumin with the formation of ammonia. 



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

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



