248 THE BACTERIOPHAGE 



role. We will see that this proposition becomes reversed when 

 similar experiments are carried out in a non-contaminated area. 



IMMUNIZATION AGAINST BARBONE 2 



Thanks to the liberality of the Government of Cochin-China, 

 which placed at our disposal all the animals, steers and buffaloes, 

 which we needed, we have been able to study in detail certain of 

 the conditions underlying immunization by means of the bac- 

 teriophage. Barbone is, indeed, an ideal disease for a study of 

 this type. The blood taken from an animal about to die of the 

 disease can be preserved in sealed ampoules for at least six months 

 without any loss in the virulence of the bacteria present. Bouil- 

 lon inoculated with a drop of this blood yields a culture which 

 regularly kills the steer or the buffalo in a dose of 0.0002 cc. 

 With half this dose, 0.0001 cc., usually one out of two animals 

 will be killed. Experimental infection reproduces the spontaneous 

 disease in the most minute details; the same temperature curve, 

 the same symptoms, the characteristic edema at the point of 

 entrance of the virus. Like the natural infection, the disease 

 is fatal; all animals succumb and death occurs in the same length 

 of time in the two cases, within twelve to eighteen hours of the 

 appearance of the first symptoms. The lesions to be found at 

 autopsy are identical. Immunization experiments conducted 

 with such a disease provide, then, absolute results. 



1 may state here, once for all, that each time that the immunity 

 of one animal has been tested by the inoculation of a culture of 

 the bacterium of barbone this test has been controlled by the 

 injection of an equal dose into a control animal of the same weight, 

 and never has the control resisted. Furthermore, although there 

 can be no possible doubt concerning the cause of death, confirma- 

 tion has always been made by microscopic examination, by blood 

 culture, and by the demonstration of the lesions at autopsy. The 

 temperature of the experimental animals was taken regularly, 

 morning and evening, and the slightest reaction in the immu- 

 nized animals could not have passed unobserved. 



2 These experiments were conducted at Saigon with the assistance of 

 G. Le Louet, Chief of the Veterinary Service in Cochin-China. 



