438 



PATHOGENIC BACTERIA. 



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- 

 cipitate rapidly ; a rather smeary, whitish mycoderma is 

 generally formed upon the surface. The much more ex- 

 tensive and more rapid liquefaction of the medium, the 

 wider top to the funnel-shaped liquefaction at the surface, 



Fig. 94. — Spirillum of Finkler and Prior : gelatin puncture-cultures aged 

 forty-eight and sixty hours (Shakespeare). 



the absence of the air-bubble, and the clouded nature of 

 the liquefied material, all serve to differentiate it from the 

 cholera spirillum. 



Upon agar-agar the growth is also very rapid, and in 

 a short time the whole surface of the culture-medium is 



