THE ORGANISMS OF SUPPURATION. 183 



round the centrej and then liquefaction of the gelatine 

 gradually takes place, starting with the first of these 

 rings, and by degrees reaching the somewhat indis- 

 tinct edges of the colony. At the same time a deep 

 ring of gelatine around each colony becomes coloured 

 bluish-green, being at first only slightly fluorescent, 

 but by degrees becoming somewhat more intensely 

 so. In puncture cultivations the gelatine is quickly 

 liquefied, and coloured bluish green. By degrees the 

 greenish-blue colour becomes converted into a dirty 

 brownish green, which in its tura becomes finally 

 quite brown. On agar-agar rather dark, dirty white, 

 slimy films are formed, whilst the nutrient medium 

 becomes gradually of an intense blue colour. In this 

 case also the originally pretty bright colour becomes 

 in time changed into an indeterminate brown. In 

 cultivations on potatoes, when these latter are either 

 alkaline in reaction, or are made so, the colonies are 

 whitish brown, whilst the medium itself is distinctly 

 green in colour. If the potatoes have an acid reaction 

 they are only faintly brownish in colour ; if after the 

 removal of the colonies they are rendered alkaline, they 

 immediately become distinctly and intensely bluish 

 green. In milk this bacillus produces a dirty though 

 bright green coloration, which is easily to be distin- 

 guished from that caused by the bacillus eyanogenus. 

 It has no special peculiarities in its behaviour to- 

 wards staining reagents, being coloured with any of 



