NON-PATHOGENIC BACTERIA. 83 



Properties. Large, shining, oval spores ; a slight movement ; 

 liquefy gelatine. 



Growth. At ordinary temperatures, with plentiful supply of 

 air. 



Plate Colonies. Look like roots of an old tree gnarled together, 

 radiating from a common centre. On surface soon liquid. 



Stab Culture. Soon a growth occurs along the needle track, 

 and the whole resembles a pine tree turned upside down. The 

 gelatine then becomes liquid, a thin skin floating on top, and 

 small flakes lying at the bottom. 



Stroke Culture. Feathery resemblance is produced. 



Staining. Spores stain readily with the ordinary spore stain. 



Bacterium Zopfii, (Kurth.) 



Origin. Intestines of a fowl. 



Form. Short thick rods forming long threads coiled up, 

 which finally break up into spores, which were once thought to 

 be micrococci. 



Properties. Very motile ; does not dissolve or liquefy gela- 

 tine. 



Growth. In thirty hours abundant growth; aerobic; grows 

 best at 20 C. 



Plates. Small white points which form the centre of a very 

 fine netting. With high power this netting is found composed 

 of bacilli in coils, like braids of hair. 



Excellent impress or "Klatsch" preparations are obtained 

 from these colonies. 



Staining. Ordinary dyes. 



Bacillus Subtilis. (Hay Bacillus.) Ehrenberg. 



Origin. Hay infusions ; found also in air, water, soil, faeces, 

 and putrefying liquids. Very common, often contaminates 

 cultures. 



Form. Large rods, three times as long as broad ; slight 

 roundness of ends, transparent; seldom found singly; usually 

 in long threads. Flagella are found on the ends. Spores of 

 oval shape, strongly shining, very resistant. 



Properties. Very motile ; dissolves gelatine. 



Growth. Rapid ; strongly serobic. 



Plate. Round, gray colonies, with depressed white centre. 



