144 BACTERIOLOGICAL EXAMINATION OF WATER. 



Gelatine Plates. Tiny circular colonies are visible under the 

 microscope in nineteen hours. In twenty-four hours they are 

 visible to the naked eye. In two days the surface colonies are 

 liquefied and appear as uniformly turbid circles, with a whitish 

 flocculent deposit at bottom. The deeper colonies are white, 

 spherical, and still very minute. In three days the colonies 

 have increased up to 10 mm., and are fused in places, the 

 plate being mostly liquefied with distinct greenish-yellow 

 fluorescence, and having a sour, faecal smell. On the fourth 

 day the plate is completely liquefied, and the fluorescence 

 brighter. 



Gelatine-stab cultures. In nineteen hours there is already 

 liquefaction at the surface, as a small flat hemisphere, 2 mm. 

 in diameter, which in two days attains a diameter of 6 or 

 7 mm., and in three days reaches the walls of the tube, 

 though not to a greater depth than 3 mm. Little growth 

 occurs along the needle track. The liquefaction always 

 advances in a horizontal plane. Greenish fluorescence is 

 marked in the liquefied portion by the fifth day; a thin 

 pellicle forms on the surface, and there is a thick whitish 

 deposit at the bottom of the liquefied portion. 



Agar-agar. No growth occurs at 37 C. At 20 C. 

 growth is rapid. In streak cultures there is a greyish-white 

 growth, with a thick, slightly irregular edge. The agar 

 acquires a brilliant greenish-yellow fluorescence. 



Broth. The growth is similar to B. fluorescens liquefaciens ; 

 marked green fluorescence appears in the surface layers after 

 the third day. 



Milk. The milk does not coagulate, but is gradually 

 digested, the upper layer becoming yellowish and transparent 

 after two days ; this change gradually spreads downwards, and 

 the upper layers show a yellowish-green tint. 



Gas production has not been observed. 



This organism is closely allied to the B. fluorescens liquefaciens, 

 but differs from it in the mode and rate of liquefaction of 

 gelatine, and in the greater brilliancy of the fluorescence it 

 produces on agar cultures, in which it resembles B. pyocyaneus. 

 From the last mentioned species it differs in its refusal to grow 

 at 37 C. 



