520 THE BACTERIOPHAGE AND ITS BEHAVIOR 



There remained but 93 out of a total of 200. The race of the bac- 

 teriophage used proved to be very virulent for the pathogenic bacillus 

 isolated from one of the dead chicks. The survivors received an in- 

 jection of 0.5 cc. of the bacteriophage suspension. Two died after the 

 injection and then the epizootic ceased. 



Kramer concluded from these experiments that the bacteriophage 

 certainly plays a role in immunity. 



To this modest conclusion I may add that the experiments of this 

 author show definitely that the immunity conferred experimentally 

 is proportionate to the virulence which the bacteriophage administered 

 has for the strain of the pathogenic bacterium which is causing the 

 epizootic. 



A favorable result, either in prophylaxis or in therapy, can hardly 

 be expected unless a race of the bacteriophage is used which has a 

 maximum virulence for the pathogenic agent against which the develop- 

 ment of an immunity is desired. To attempt to work with races of 

 low virulence is simply to invite certain failure. 



3. IMMUNIZATION AGAINST BARBONE 



Together with Le Louet, one-time Chief of the Veterinary Service 

 of Cochin-China, I have made some studies on immunity in barbone, 

 or hemorrhagic septicemia of the buffalo. 



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 bacteriophage. 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. Bouillon 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 spon- 

 taneous 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 from 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. 



