BACTERIUM COLI COMMUNE. 327 



of producing iudol in solutions of peptone ; the growth 

 of the colon bacillus in these solutions is accompanied 

 by the production of indol in from forty-eight to seventy- 

 two hours at 37 to 38 C. 



Animal inoculations. As with the bacillus of typhoid 

 fever, the results of inoculation of animals with cultures 

 of this organism cannot be safely predicted. According 

 to the observations of Escherich, Emmerich, Weisser, 

 and others, the results that do appear are in most in- 

 stances to be attributed to the toxic rather than to the 

 infective properties of the culture used. 



When introduced into the subcutaneous tissues of 

 mice it has no effect, while similar inoculations of 

 guinea-pigs are sometimes (not always) followed by 

 abscess formation at the point of injury, or by altera- 

 tions very similar to those produced by intra- vascular 

 inoculation, viz. : death in less than twenty-four hours, 

 accompanied by redness of the peritoneum and marked 

 hypersemia and ecchymoses of the small intestine; 

 together with swelling of Peyer's patches. The caecum 

 and colon may remain unchanged or present enlarged 

 follicles. There may or may not be an accumulation 

 of fluid in the abdominal cavity, but peritonitis is rarely 

 present. The small intestines may contain bloody 

 mucus. 



Intra-venous inoculation of rabbits may be followed 

 by similar changes with often the occurrence of diar- 

 rhoea before death, which may, in the acute cases, result 

 in from three to forty hours. In another group of 

 cases acute fatal intoxication does not result, and the 

 animal lives for weeks or months, dying ultimately of 

 what appears to be the effects of a slow or chronic form 

 of infection. For a few hours after inoculation these 



