362 BAaXEBIOLOGY. 



panied by the production of indol in from forty-eight 

 to seventy-two hours at 37° to 38° C. 



8. When twenty-four hours old bouillon cultures of 

 both organisms are brought in contact with the blood- 

 serum from a case of genuine typhoid fever (after the 

 fifth day of the disease), the characteristic agglutination 

 (clumping) of the bacilli occurs in the typhoid culture 

 and not in that of the colon bacillus (Widal's reaction). 



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 alterations very 

 similar to those produced by intravascular 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 intestine may contain bloody mucus. 



Intravenous 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 



