PATHOGENIC BACTERIA 143 



A toxalbumin and a toxic peptone have been isolated, but no 

 special actions ascribed to them. 



Detection of Cholera Organisms in Drinking-water. When 

 a few bacteria are supposed to be present in fecal matter or 

 drinking-water, it is best to add a large quantity of the material 

 (200 c.c. of drinking-water) to about 10 c.c. of bouillon or 

 peptone-water, and place the mixture for twenty-four hours in 

 an incubator, which will cause rapid reproduction, and then 

 the organisms can be readily discovered. 



Fig- 73. Comma bacillus in mucus, from a case of Asiatic cholera. 



Protective Vaccines. Virulent cultures killed by heat have 

 shown protective power and were used extensively during an 

 epidemic in Japan. 



Haffkine has obtained a great reduction in mortality in 

 cholera regions by the use of anticholera vaccines as protective 

 and curative measures. 



Cholera Immunity of Pfeiffer. Intraperitoneal, subcuta- 

 neous, and intravenous injections of living or dead cholera 

 bacteria cause a disease in animals similar to the cold stage of 

 cholera. Death is the result of toxemia. If the animal lives, 



