268 PATHOGENIC BACTERIA. 



A study of the growth of the organism and the forms 

 which it assumes upon different culture-media soon con- 

 vinces us that we have to do with an organism in no way 

 related to the bacilli. If the conditions of nutrition are 



FIG. 77. Spirillum of Asiatic cholera, showing the flagella; x 1000 (Giinther). 



diminished so that the multiplication of the bacteria by 

 simple division does not progress with the usual rapidity, 

 we find a distinct tendency toward and in some cases, 

 as upon potato, a luxuriant development of long spiral 

 threads with numerous windings unmistakable spirilla. 

 Frankel has found that the exposure of cultures to unusu- 

 ally high temperatures, the addition of small amounts 

 of alcohol to the culture-media, etc., will so vary the 

 growth of the organism as to favor the production of 

 spirals instead of commas. One of the most common 

 of the numerous forms observed is that in which two 

 short curved individuals are so joined as to produce an 

 S-shaped curve. 



The cholera spirilla are exceedingly active in their 

 movements, and in hanging-drop cultures can be seen 

 to swim about with great rapidity. Not only do the 

 comma-shaped organisms move, but when distinct spirals 

 exist, they, too, move with the rapid rotary motion so 

 common among the spirilla. 



