4io 



PATHOGENIC BACTERIA. 



examined in the living condition it is found to be non- 

 motile. 1 



The bacillus readily succumbs to the action of heat 

 and dryness. The cultures upon gelatin plates after 

 about two days appear as irregular, small, white points. 

 The deep colonies reach the surface slowly, and do not 

 attain any considerable size. The gelatin is not lique- 

 fied. The microscope shows the colonies to be irregularly 



FlG. 112. Bacillus of chicken-cholera, from the heart's blood of a pigeon; 

 x 1000 (Frankel and Pfeiffer). 



rounded disks with distinct smooth borders. The color 

 is yellowish-brown, and the contents are granular. Some- 

 times there is a distinct concentric arrangement. 



In gelatin puncture-cultures a delicate white line occurs 

 along the entire path of the wire. When viewed through 

 a lens this line is seen to consist of aggregated mi- 

 nute colonies. Upon the surface the development is 



1 Most authorities state that the bacillus is not motile, but Thoinot and Mas- 

 uelin assert that it is so. Precis tic Microi>ie, 2d ed., 1893. 



