NON- PATHOGENIC BACTERIA 99 



Some Non-pathogenic Bacteria Found in Water. The 

 bacteria found are very often given to producing pigments or 

 phosphorescence, and are a great number; they frequently 

 give rise to foul gases and, for the most part, liquefy gelatin 

 rapidly. 



Bacillus Violaceus. Origin. Water. 



Form. A slender rod with rounded ends, three times as long 

 as it is broad, often in threads; middle-sized spores. 



Properties. Very motile; forms a violet-blue pigment, which 

 is soluble in alcohol, and depends upon oxygen for its growth. 

 Rapidly liquefies gelatin, but not agar. 



Growth. Grows fairly quick, is facultative anaerobic. 



Cultures on Plate. At first the colonies look like inclosed air- 

 bubbles. Low power shows irregular masses, with a center 

 containing the pigment and a hairy-like periphery. 



Stab-culture. Cone-like liquefaction containing air, and the 

 pigment, in separated granules, lying toward the bottom. 



Stroke Culture on Agar. A violet, ink-like covering which 

 remains for years. 



Bacillus Coeruleus (Smith) . Origin. Schuylkill water. 



Form. Very thin rods; 2.5 // long, 0.5 /* wide; often in 

 threads; spores were not found. 



Properties. Liquefies gelatin; produces a very deep-blue 

 pigment. 



Growth. Slowly, with oxygen, at ordinary temperature. 



Plate. Round colonies on the surface of bluish color. 



Stab-cultures. A cup-shaped liquefaction along the needle- 

 thrust, with a sparse growth, the liquefied portion appearing 

 blue. 



Fluorescent Bacteria. Several kinds present in water. 



Bacillus Erythrosporus (Eidam) . Origin. Drinking- 

 water and putrefying albuminous solutions. 



Form. Slender rods, often in short threads, with spores of 

 oval shape, and appearing as if stained with fuchsin. 



Properties. Motile; does not dissolve gelatin; produces a 

 greenish, fluorescent pigment, which appears yellow in reflected 

 light, but green on transmitted light. 



