754 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



when magnified, appear circular and opaque. In seven days the 

 colonies, which remain punctiform, are surrounded by a zone of 

 softened gelatine, and microscopically they are seen to have a 

 rough outline and a margin like a yeast colony. The gelatine- 

 stab becomes filiform and faintly tuberculate. On agar the 

 stroke is porcelain-white and remains narrow ; the margin is 

 lobular, and the growth spreads irregularly at the base. There 

 is a good growth upon potato, but it is indistinguishable from the 

 medium. Bouillon becomes turbid and forms a coherent sediment, 

 but no film. Milk is coagulated and the reaction becomes acid. 

 The culture on litmus-lactose-agar reddens the litmus, but docs 

 not produce gas in the medium. Nitrate is reduced to nitrite, 

 indol is formed in bouillon, and gas is not produced from glucose. 

 The organism was separated by Jordan's method on account of 

 its reddening litmus. It appears to be Mic. pyogenes y albus, 

 Rosenbach. 



Bacillus mesentericus nicer, Lunt. 



This member of the potato bacilli is a motile rod, with rounded 

 ends, and measures 06: 1-7-3/*. It forms oval central spores, 

 and is stained by Gram's method. The growth upon potato is 

 very much folded and dry; it soon covers the entire surface, and 

 becomes black in colour. The potato is also blackened. The 

 stroke on agar is at first translucent-white and gummy; it is 

 ir regular ly raised, but has a practically straight margin and 

 smooth edge. The condensed water becomes covered with a 

 tough film. The upper smooth and shining part of the agar 

 growth gravitates into the dry and rough lower portion. The 

 medium slowly becomes black, and the growth grey-black. 

 Litmus-lactose-agar is not reddened. Gelatine is liquefied; the 

 colonies have a white centre and margin, and as they grow older 

 white rays stretch out beyond the liquid margin. The stab in 

 gelatine is filiform below a tubular liquefied area; there are no 

 lateral processes. The liquefaction becomes stratiform, and 

 a strong film forms on the surface. No gas is produced from 

 glucose. The lower layers of the bouillon culture remain clear, 



