BACILLUS PHOSPHORESOENS 133 



yellow, forming variously shaped flakes. The thrust-culture 

 is of a slightly conical or sand-glass form, with a thin de- 

 posit on the edge of the gelatine ; but in old cultivations 

 the colonies become heaped on the bottom without fluid. 

 The light given off by them is of a bluish- white colour, and if 

 traces of the culture be added to sea-water, it acquires the 

 property of phosphorescence like that observed at sea. 



Closely allied to the foregoing is the Bacillus phos- 

 phorescens indieus, or Indian luminous bacillus, which was 

 also found in sea-water by Fischer, and which forms small, 

 thick, energetically- motile rods. Bound, sharply-defined 

 colonies develop on the gelatine plate about the third day, 

 and are also of a sea-green colour with a rosy shimmer, but 

 later turn dirty yellow. The thrust- 

 culture shows on the fourth day a 

 cavity filled with air on the site of 



the puncture, and later the loss of Tgj^ \ 



substance increases, the liquefied ^gt 



gelatine being covered by a dirty 

 yellow pellicle. A white layer de- 

 velops on potato. Boiled fish and „ 



^ ^ Fig. 46.— Islet of Bacillus ka- 



meat furnish a good medium for ™pLc°e1s^o.''SZ'?ac™T' 

 the growth of the micro-organism, 



which is checked at temperatures below 10° C. The fact of 

 its growing on potato distinguishes it from the indigenous 

 species. In the presence of air and moisture it shows a 

 luminosity in the dark, best at a temperature of 25° to 

 30° C. Both bacilli admit of being photographed by their 

 own light. They grow best on herring gelatine, which is 

 prepared in a manner similar to ordinary gelatine. 



Bacillus ramosus, or root-bacillus (WurzelbaciUus) , shows 

 short rods with rounded ends and possessing slight power 

 of movement, and is found in the water both of wells and 

 rivers, and also on the surface of the ground. Small 



