BACILLI IN WATER 131 



related to the above-described fluorescent but liquefactive 

 bacilli has been discovered in the Bacillus fluorescent 

 non-liquefacicns, small rods destitute of motility which form 

 on the gelatine plate shimmering colonies with indented 

 edges, having a darker spot in the centre, and a lighter 

 coloured leaf-like figure all round. In thrust-cultures there 

 is a superficial growth of considerable vigour, but nothing 

 can be observed along the needle-track ; the shimmer, how- 

 ever, pervades the whole of the gelatine. This bacterium 

 is distinguished from the Bacillus erytlirosporus by the fact 

 that the latter shows red-coloured spores. 



Bacillus erythrosporus was found by Eidam in drinking- 

 water and in various putrefying albuminous fluids. The 

 rods are slender, have rounded corners, and are actively 

 motile, and the cultures are characterised by the develop- 

 ment of a dichromatic pigment, appearing orange-yellow by 

 direct, green by transmitted light. The colonies on the 

 gelatine plate are circular, and show in the centre a darker 

 spot around which spreads a wider light zone. Round 

 every colony fluorescence appears, and soon spreads over 

 the gelatine, so that the entire plate exhibits the phenome- 

 non. Thrust-cultures show a growth upon the surface from 

 which the fluorescence advances deeper until it extends 

 along the whole track of inoculation. A reddish colour, 

 becoming later nut-brown, develops on potato. The spores 

 are characterised by a red gleam, which gives them the ap- 

 pearance of being stained with fuchsine. 



Bacillus arborescens has been frequently detected by 

 P. Frankland in the water-supply of London. Its rodlets 

 are thin and motile, and it appears on gelatine plates in 

 iridescent colonies resembling a trunk with its branches, 

 the latter being arranged in sheaves. A superficial irides- 

 cence is visible likewise in the thrust-cultures, and slow 

 liquefaction soon sets in ; while on agar and potato a yellow 



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