204 TECHNOLOGY OF BACTERIA. 



small bird, sparrow or canary, to which it is 

 fatal. After several successive inoculations from 

 bird to bird, the virus resumes its original activity. 



Method of Toussaint. The effect produced upon 

 pathogenic organisms by prolonged exposure to 

 oxygen, Toussaint proposes to produce more ex- 

 peditiously, by subjecting them for a short time to 

 a temperature a little less than is required for the 

 complete destruction of vitality. 



According to Chauveau, this is best accomplished, 

 in the case of Bacillus anthracis, by exposure for 

 eighteen minutes to a temperature of 50 C. Ex- 

 posure to this temperature for twenty minutes is 

 said to kill the bacillus ; while " heating for eighteen 

 minutes produces an excellent attenuated virus for 

 vaccination." 



A first vaccination with feeble virus (heated to 

 50 for fifteen minutes), and a second inoculation, 

 at the end of fifteen days, with a strong virus (blood 

 heated to 50 for nine or ten minutes), preserves 

 sheep from the effects of subsequent inoculations 

 with virus of full strength. The heating must be 

 in small tubes, not more than 1 mm. in diameter ; 

 and at the end of the time fixed these must be 

 quickly withdrawn from the hot bath and plunged 

 into cold water. 



The blood of a guinea-pig which has just died 

 from anthrax, at the end of thirty-six to forty-eight 

 hours from the time of inoculation, is said to be a 

 good active virus upon which to operate by this 



