BACILLUS CO LI 533 



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 bacillm 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 



