Cultivation 623 



Cultivation. 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. 



Colonies. Upon gelatin plates the growth of the colonies 

 is much more rapid than that of the cholera spirillum, 

 though slower than that of the Kinkier and Prior spirillum. 

 The colonies appear as small whitish, round points, which 



Fig. 216. Spirillum of Denecke, from an agar-agar culture. X 1000 

 (Itzerott and Niemann). 



soon reach the surface of the gelatin and commence lique- 

 faction. By the second day each is about the size of a 

 pin's head, has a yellow color, and occupies the bottom of 

 a conical depression. The appearance is much like that 

 of colonies of the cholera spirillum. 



The microscope shows the colonies to be of irregular 

 shape and coarsely granular, pale yellow at the edges, 

 gradually becoming intense toward the center, and at first 

 circumscribed, but later surrounded by clear zones, resulting 

 from the liquefaction of the gelatin. These, according to 

 the illumination, appear pale or dark. The colonies differ 

 in appearance from those of cholera in the prompt lique- 

 faction of the gelatin, their rapid growth, yellow color, 

 irregular form, and distinct lines of circumscription. 



Gelatin Punctures. In gelatin punctures the growth 

 takes place all along the track of the wire, and forms a 

 cloudy liquid which precipitates at the apex in the form of 



