ASIATIC CHOLERA AND THE CHOLERA ORGANISM 835 



hours at 37.5 C. the surface growths in these flasks are examined 

 both microscopically and culturally as before. 



Biological Considerations. The cholera spirillum is aerobic and 

 facultatively anaerobic. It does not form spores. The optimum 

 temperature for its growth is about 37.5 C. It grows easily, how- 

 ever, at a temperature of 22 C. and does not cease to grow at 

 temperatures as high as 40. Frozen in ice, these bacteria may 

 live for about three or four days. Boiling destroys them imme- 

 diately. A temperature of 60 C. kills them in an hour. In impure 

 water, in moist linen, and in food stuffs, they may live for many 

 days. Associated with saprophytes in feces and other putrefying 

 material, and wherever active acid formation is taking place, they 

 are destroyed within several days. Complete drying kills them in 

 a short time. The common disinfectants destroy them in weak 

 solutions and after short exposures (carbolic acid, five-tenths per 

 cent in one-half hour ; bichlorid of mercury, 1 :100,000 in ten minutes ; 

 mineral acids, 1:5,000 or 10,000 in a few minutes). 



Cholera in Man. In man the disease is contracted by ingestion of 

 cholera organisms with water, food, or any contaminated material. The 

 disease is essentially an intestinal one. The bacteria, very sensitive to 

 an acid reaction, may often, if in small numbers, be checked by the 

 normal gastric secretions. Having once passed into the intestine, 

 however, they proliferate rapidly, often completely outgrowing the 

 normal intestinal flora. Fatal cases, at autopsy, show extreme con- 

 gestion of the intestinal walls. Occasionally ecchymosis and localized 

 necrosis of the mucosa may be present and swelling of the solitary 

 lymph-follicles and Peyer's patches. Microscopically the cholera 

 spirilla may be seen to have penetrated the mucosa and to lie within 

 its deepest layers close to the submucosa. The most marked changes 

 usually take place in the lower half of the small intestine. The 

 intestines are filled with the characteristically fluid, slightly bloody, 

 or "rice-water" stools, from which often pure cultures of the cholera 

 vibrio can be grown. The microorganisms can be cultivated only 

 from the intestines and their contents, and the parenchymatous 

 degenerations taking place in other organs must be interpreted as 

 being purely of toxic origin. 



Tli ere is at the same time a profound toxemia due, in part, at 

 least to the absorbed cholera substances. 



The incubation time of the disease is usually short, lasting from 

 a few hours to several days. The disease usually begins, with diar- 



