PATHOGENIC BACTERIA. 127 



cholera bacillus a rose-red color is produced. This will not take 

 place with other bacilli unless nitrous aqid is present. The cholera 

 bacillus forms nitrites from the nitrates present in the media, 

 and also indol. The mineral acid splits the nitrites, setting free 

 nitrous acid, which, with the indol, forms the red reaction. 

 This pigment has been isolated and extracted and called 

 " cholera red." A ptomaine, identical with caclaverin, and sev- 

 eral other alkaloids have been obtained from the cultures. A 

 toxalbumen and a toxicpeptone have lately 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. cm. of drinking-water) to about 10 c. cm. of bouillon, and 

 place the mixture for twenty-four hours in an incubator, 

 which will cause rapid reproduction, and then the organisms 

 can be readily discovered. 



Haffkine has obtained a great reduction in mortality in 

 cholera regions by the use of anti-cholera vaccines as pro- 

 tective and curative measures. 



Cholera Immunity of Pfeiffer. Intraperitoneal, subcutaneous, 

 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, the blood 

 has protective properties of a specific nature; it has bacteri- 

 cidal properties against cholera vibrio, and by the injection of 

 this serum into non-immune animals it renders them immune. 

 The blood-serum of convalescents and cholera-vaccinated indi- 

 viduals contains the same bactericidal substances. 



Bacteria Similar to the Spirillum of Cholera. 



Finkler-Prior Vibrio, or Spirillum Finkleri. 



Origin. Found in the intestinal contents of a patient suffer- 

 ing from cholera Asiatica in 1884, by Finkler and Prior, who 

 thought it identical with the spirillum of cholera; it differs 

 from it, however, in many ways, and has been found in healthy 

 persons. 



Form. Somewhat thicker than the cholera vibrio: but forms 

 the long spirilla less often. Has flagella. 



