BACILLI RESEMBLING TYPHOID BACILLUS. 515 



pairs. When stained with methylene-blue the ends color 

 deeper than the middle; and organisms from old, in- 

 voluted cultures color irregularly. It does not stain by 

 Gram's method, has no observable spores, is not motile, 

 and has no demonstrable flagella. It does not liquefy 

 gelatin. It grows slowly at ordinary temperatures; 

 rapidly at the temperature of the body. The culture- 

 media should be alkaline. Its death-point is 68° C, 

 after twenty minutes' exposure. 



. The colonies upon gelatin plates are small, dewdrop- 

 like in appearance, and upon microscopic examination 

 are seen to be of regular outline and spherical form. By 

 transmitted light they appear granular and of a yellowish 

 color. The colonies do not spread out in a thin pellicle 

 like those of the colon bacillus, and there are no essential 

 differences between the superficial and deep colonies. 



The puncture culture in gelatin consists of crowded, 

 rounded colonies forming a grayish-white growth along 

 the puncture. There is no liquefaction. 



Upon the surface of agar-agar in the incubating-oven 

 large, solitary colonies are evident at the end of twenty- 

 four hours. They are of bluish-white color and rounded 

 form. The surface appears moist. In the course of 

 forty-eight hours a transparent border is observed about 

 each colony, and the bacilli of which it is composed 

 cease to stain evenly, presenting involution-forms. 



Glycerin agar-agar seems less well adapted to their 

 growth than plain agar-agar. Blood-serum is not a suit- 

 able medium. 



In gelatin and agar-agar containing sugars no gas is 

 evolved. 



Upon boiled potato the young growth resembles that 

 of the typhoid bacillus, but after twenty-four hours it 

 becomes yellowish -brown, and at the end of a work forms 

 a thick brownish-pink pellicle. 



In bouillon the bacillus grows well, clouding the liquid. 

 No pellicle forms on the surface. 



The organism does not form indol. Acids are produced 



