330 PATHOGENIC BACTERIA. 



The Spirillum of Denecke. Another organism with 

 a distinct resemblance to the cholera spirillum is one 

 described by Denecke as occurring in old cheese (Fig. 

 87). Its form is much the same as that of the spirillum 

 of cholera, the shorter individuals being of equal diameter 

 throughout. The spirals which are produced are longer 

 than those of the Finkler and Prior spirillum, and are 

 more tightly coiled than those of the cholera spirillum. 



Like its related species, this micro-organism is actively 

 motile. It grows at the room-temperature, as well as at 

 37 C., in this respect, as in its reaction to stains, much 

 resembling the other two. 



Upon gelatin plates the growth of the colonies is much 

 more rapid than that of the cholera spirillum, but slower 

 than that of the Finkler and Prior spirillum. The col- 



FIG. 87. Spirillum Denecke, from an agar-agar culture ; x 1000 (Itzerott 

 and Niemann). 



onies appear as small whitish, round points, which soon 

 reach the surface of the gelatin and commence liquefac- 

 tion. By the second day they are about the size of a 

 pin's head, have a yellow color, and occupy the bottom 

 of a conical depression. The appearance is much like 

 that of a plate of cholera spirilla. 



The microscope shows the colonies to be of irregular 



