IMMUNIZATION BY MEANS OF THE BACTERIOPHAGE 245 



effect. The epizootic stopped abruptly after an inoculation of bacterio- 

 phage active for the bacillary agents of the paratyphoses, made on Feb- 

 ruary 17. 



Examination of the blood of fowls dead in Barnyard No. 12 resulted in 

 the isolation of a B. pfaffi, type of bacillus. This organism, then, was 

 responsible for the epizootics in groups 11 and 12. In this connection I will 

 only mention the instance of the epizootic of paratyphosis at Trainel of 

 which I have spoken in the chapter on avian typhosis. This outbreak was 

 likewise due to B. pfaffi, and was controlled by the inoculation of an anti- 

 pfaffi bacteriophage. 



Experiment II. This was performed at Poully en Auxois 

 with the assistance of MM. Voillot and Bouhier, D.V.M. 



Barnyard 1. On January 5, 20 chickens were taken at random from 

 a poultry-yard containing about 100 fowls where typhosis had appeared. 

 These 20 were immunized with a culture of anti-gallinarum bacteriophage. 

 On February 7 the immunized birds were all alive and in perfect condition, 

 while the epizootic had continued to spread among the non-immunized 

 animals, of which only about 20 remained. 



Barnyard 2. On February 23 the surviving chickens of a poultry-yard 

 containing at that time 102 animals were immunized. The epizootic which 

 began about 10 days previously, and which had resulted in a daily mortality 

 of 4 or 5 chickens, stopped quickly and permanently from the time of the 

 immunization. The epizootic continued, on the contrary, to ravage with 

 the same intensity as formerly in all the neighboring poultry-yards which 

 served as controls. 



Experiment III. This experiment was conducted at Provins 

 with the aid of M. Sorriau D.V.M. , in an important poultry- 

 yard where typhosis was present in endemic form. 



For several months the daily mortality had been 2 or 3 fowls. On Jan- 

 uary 25 the 225 survivors were immunized. The epizootic immediately 

 and permanently disappeared from the date of the immunization. 



Experiment IV. Performed at Rouillac, Charente, with the 

 assistance of M. Chollet, D.V.M. 



On December 15, 100 fowls were immunized in a poultry-yard where 

 typhosis had appeared about ten days previously. The daily mortality 

 had been from 4 to 6 animals. With the immunization there was an imme- 

 diate and permanent cessation of the epizootic. Typhosis continued to 

 prevail on all the neighboring farms. Among the 100 chickens inoculated, 

 about 12 were already affected. Of these only 2 died, 2 and 3 hours after 

 the injection. 



