PATHOGENIC BACTERIA 



the cholera spirillum, and also of making a diagnosis 

 of the disease in a suspected case, is probably that of 

 Schottelius. The method is very simple : A small quan- 

 tity of the fecal matter is mixed with bouillon and stood 

 in an incubating oven for twenty-four hours. If the 



FIG. 82. Spirillum of Asiatic cholera; colonies two days old upon a gelatin 

 plate; x 35 (Heim). 



cholera spirilla are present, they will grow most rapidly 

 at the surface of the liquid when the supply of air is 

 good. A pellicle will be formed, a drop from which, 

 diluted in melted gelatin and poured upon plates, will 

 show typical colonies. 



Under the microscope the principal characteristics 

 can be made out. The colony of the cholera spirillum 

 scarcely resembles that of any other organism. The little 

 colonies which have not yet reached the surface of the 

 gelatin begin very soon to show a pale-yellow color and 

 to exhibit irregularities of contour, so that they are 

 almost never smooth and round. They are coarsely 

 granular, and have the largest granules in the centre. 

 As the colony increases in size the granules also increase 



