324 BACTERIOLOGY. 



It grows both with and without oxygen. 



On gelatin. When on the surface, its colonies appear 

 small, dry, irregular, flat, blue-white points that are 

 commonly somewhat dentated at the margin. They are 

 a trifle denser at the centre than at the periphery, and 

 are often marked at or near the middle by an oval or 

 round nucleus-like mass the original colony from which 

 the layer on the surface developed. When located in 

 the depths of the gelatin, and examined with a low- 

 power lens, they are at first seen to be finely granular 

 and of a very pale greenish-yellow color ; later they 

 become denser, darker, and much more markedly granu- 

 lar. In shape they are round, oval, and lozenge-like. 

 When the surface colonies are viewed under a low power 

 of the microscope they present essentially the same ap- 

 pearance as that given for the bacillus of typhoid fever, 

 viz., they resemble flattened pellicles of glass-wall, or 

 patches of finely ground colorless glass. Colonies of this 

 organism on gelatin are frequently encountered that 

 cannot be distinguished from those resulting from the 

 growth of the bacillus of typhoid fever, though, as a 

 rule, their growth is a little more luxuriant. 



In stab and smear cultures on gelatin the surface 

 growth is flat, dry, and blue-white or pearl color. 

 Limited growth occurs along the track of the needle in 

 the depths of the gelatin. As the culture becomes older, 

 the gelatin round about the surface growth may gradu- 

 ally lose its transparency and become cloudy, often quite 

 opaque. In still older cultures small roots, or branch- 

 like projections from the surface growth into the gelatin 

 are sometimes seen to occur. 



It does not cause liquefaction of gelatin. 



