CHOLERA BACTERIA 151 



best to make several plantings from the peptone to agar after 

 six hours' growth. 



Dieudonne's Medium. (See p. 77.) In this cholera vibrio 

 grow abundantly; other intestinal bacteria very scantily. 

 This medium valuable mostly for feces, less for infected water. 



Staining. They are colored well with watery anilin solu- 

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

 the flagella stain or Giemsa. 



Pathogenesis. Experiment animals are not subject to 

 cholera Asiatica, but, by overcoming two obstacles, Koch 

 produced choleraic symptoms in guinea-pigs. Nicati and 

 Rietsch prevented peristalsis and avoided the acidity of the 

 stomach-juices by direct injection into the duodenum, after 

 tying the gall-duct. Koch alkalinized the gastric juice with 

 5 c.c. of 5 per cent, solution of sodium carbonate, and then 

 injected 2 grams of opium tincture for every 300 grams of 

 weight into the peritoneal cavity, paralyzing peristalsis. The 

 cholera culture then introduced through a stomach-tube, the 

 animals die in forty-eight hours, presenting the same symp- 

 toms in the appearance of the intestines as in man, the serous 

 effusion containing great numbers of spirilla. Rabbits in- 

 jected into the ear veins with cholera cultures die very quickly 

 and present intestinal lesions. The vibrio is met with in the 

 layer of flaky mucus which coats the surface of the intestine. 



It may invade the biliary passages. 



Manner of Infection in Man. Usually through the alimen- 

 tary tract, with the food or drink, the intestinal discharges of 

 cholera patients having found entrance into the source of 

 drinking-water. Soiled clothes to fingers, fingers to the 

 mouth, etc.; torpid catarrhal affection of the digestive tract 

 predisposing. The spirilla are not found in the blood or any 

 organ other than the intestines the tissue of the small intes- 

 tines. They are also found in the vomit and the intestinal 

 contents. 



Toxins. From broth cultures soluble toxins which have a 

 hemolytic action have been isolated. The toxin is easily 

 destroyed by heat (thermolabile). 



