836 PATHOGENIC MICROORGANISMS 



rhea which gradually becomes more violent until the colorless 

 typical, rice water stools appear. Castellani and Chalmers describe 

 the further course as follows: 



"Vomiting generally appears early, food being first expelled, fol- 

 lowed later by watery fluid with which bile and occasionally blood 

 may be mixed. As the purging and vomiting persist the urine 

 diminishes and may stop, and fluid departs from the subcutaneous 

 tissues, which therefore contract so that the face alters, the nose 

 becoming sharp, the cheekbones prominent, and eyes sunken and the 

 skin of the fingers becomes wrinkled like that of a washerwoman. ' ' 



A considerable role is played in the subsequent course of the 

 disease by the depletion of water, with consequent aneuria, low blood 

 pressure, cyanosis, acidosis, etc. The therapeutic effect of saline 

 infusions is said to be astonishing. 



Animal Pathogenicity. In animals, cholera never appears as a 

 spontaneous disease. Nikati and Rietsch 4 have succeeded in produc- 

 ing a fatal disease in guinea-pigs by opening the peritoneum and 

 injecting cholera spirilla directly into the duodenum. Koch 5 suc- 

 ceeded in producing a fatal cholera-like disease in animals by in- 

 troducing infected water into the stomach through a catheter after 

 neutralization of the gastric juice with sodium carbonate. At the 

 same time, he administered opium to prevent active peristalsis. A 

 method of infection more closely analogous to the infection in man 

 was followed by Metchnikoff, who successfully produced fatal dis- 

 ease in young suckling rabbits by contaminating the maternal teat. 



Subcutaneous inoculation of moderate quantities of cholera 

 spirilla into rabbits and guinea-pigs rarely produces more than a 

 temporary illness. Intraperitoneal inoculation, if in proper quan- 

 tities, generally leads to death. It will be remembered that when 

 working with intraperitoneal cholera inoculations the phenomenon 

 of bacteriolysis was discovered by Pfeiffer. 



Different strains of cholera spirilla vary greatly in their virulence. 

 The virulence of most of them, however, can be enhanced by re- 

 peated passages through animals. Most of our domestic animals 

 enjoy considerable resistance against cholera infection, though under 

 experimental conditions successful inoculations upon dogs, cats, and 

 mice have been reported. Doves are entirely insusceptible. 



4 Nikati und Eietsch, Deut. med. Woch., 1884. 



5 Koch, Deut. med. Woch., 1885. 



