506 APPLICATION OF METHODS OF BACTERIOLOGY 



first seen to be finely granular and of a very pale greenish- 

 yellow color; later they become denser, darker, and much 

 more markedly granular; in shape they are round, oval, 

 and lozenge-like. When the surface colonies are viewed 

 under a low power of the microscope they present essen- 

 tially the same appearance as that given for the colonies 

 of the bacillus of typhoid fever, viz., they resemble flattened 

 pellicles of glass-wool, or patches of finely ground colorless 

 glass. Colonies of this organism on gelatin are frequently 

 encountered that cannot be distinguished from those result- 

 ing from the growth of bacillus typhosus; although, 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 gradually lose its trans- 

 parency and become cloudy, often quite opaque. In still 

 older cultures small root- or branch-like projections from 

 the surface-growth into the gelatin are sometimes seen. 

 At times these may be of a distinctly crystalline appear- 

 ance. 



It does not cause liquefaction of gelatin. 



Its growth on nutrient agar-agar and on blood-serum is 

 luxuriant, but not characteristic. 



In bouillon it causes diffuse clouding with sedimentation. 

 In some bouillon cultures an attempt at pellicle-formation 

 on the surface may be seen, but this is exceptional. In old 

 bouillon cultures the reaction becomes alkaline and a decided 

 fecal odor may be detected. 



Its growth on potato is rapid and voluminous, appearing 

 after twenty-four to thirty-six hours in the incubator as a 



