PATHOGENIC BACTERIA. 



125 



Stab Culture. After 30 hours a growth can be distinguished 

 along the needle track, and on the surface a little cavity has 

 been formed, filled up by a bubble of air, and this liquefaction 

 proceeds until on the sixth day it has reached the sides of the 

 tube, tapering, funnel-shaped to the bottom of the tube. After 

 several weeks the spirilla 



are found in little collec- FlG - 64 - 



tions at the bottom of the 

 fluid gelatine. In eight 

 weeks the bacilli have 

 perished. 



Agar. Stroke cultures. 

 A shiny white layer lasts 

 many months. 



Potato. A yellow honey- 

 like transparent layer, if 

 the potato is kept at ani- 

 mal heat. 



Bouillon. A wrinkled 

 scum is soon formed in 

 bouillon. They live wel] 

 and grow in sterilized mills 



and Sterilized water, r* cholera colonies after 30 hours 100 X. (Frankel 



maining virulent in the and Pfeiffer.) 



latter for many months. 



In ordinary water, the bacteria present are destructive to the 



comma bacillus, and they die in a few days. 



Dunham's Peptone Solution. Useful for the development of 

 nitrites and the indol reaction. 



WidaVs serum test, as used in typhoid, is applicable in the 

 diagnosis of cholera, using cholera cultures in place of the 

 typhoid. 



Staining. They are colored well with watery aniline solu- 

 tions. The flagella can be well seen by staining according to the 

 flagella stain. 



Pathtxjenesis. Experiment animals are not subject to cholera 

 Asiatica, but by overcoming two obstacles Koch has produced 

 choleraic symptoms in guinea-pigs. Nicati and Bletsch pre- 

 vented peristalsis and avoided the acidity of the stomach juices 



