374 INFECTIVE DISEASES. 



On agar a slightly yellowish growth is obtained, resembling that 

 of Koch's commas ; on potato a yellowish -brown or chocolate layer 

 develops after incubation at the temperature of the blood, very 

 similar to cultures from Asiatic cholera. Broth becomes turbid, and 

 a wrinkled film forms on the surface ; the addition of sulphuric acid 

 gives the indol test. The spirilla grow in milk, and coagulate it ; 

 the milk becoming strongly acid, and the casein being precipitated. 

 They are pathogenic in chickens, pigeons, and guinea-pigs. Pigeons 

 die in about twelve hours after a subcutaneous injection ; and the 

 spirilla are found abundantly in blood from the heart. Guinea-pigs 

 die from acute septicaemia in about twenty-four hours. The spirilla 

 are found in the blood and internal organs. Inoculation of pigeons 

 and guinea-pigs with sterilised cultures will produce immunity. 



