282 PATHOGENIC BACTERIA. 



situated at its end, and is actively motile. Although at 

 first thought to be a variety of the cholera germ, marked 

 differences of growth were soon observed, and showed 

 the organism to be a separate species. 



The growth upon gelatin plates is quite rapid, and leads 

 to such extensive liquefaction that four or five dilutions 

 must frequently be made before the growth of a single 

 colony can be observed. To the naked eye the colonies 

 appear as small white points in the depths of the gelatin 

 (Fig. 82). They, however, rapidly reach the surface^ 



FIG. 82. Spirillum of Finkler and Prior: colony twenty-four hours old, as 

 seen upon a gelatin plate; x 100 (Frankel and Pfeiffer). 



begin liquefaction of the gelatin, and by the second 

 day appear about the size of lentils, and are situated in 

 little depressions. Under the microscope they are of a 

 yellowish-brown color, are finely granular, and are sur- 

 rounded by a zone of sharply circumscribed liquefied 

 gelatin. Careful examination with a high power of the 

 microscope shows a rapid movement of the granules of 

 the colony. 



In gelatin punctures the growth takes place rapidly 

 along the whole puncture, forming a stocking-shaped 

 liquefaction filled with cloudy fluid which does not pre- 



