IMMUNIZATION BY MEANS OF THE BACTERIOPHAGE 243 



may be found in the same areas, as is also true for human enteric 

 infections. In routine practise the solution is simple; it is sufficient 

 to immunize the poultry with a mixture of cultures of different 

 strains of the bacteriophage active against the diverse pathogens, 

 the causes of typhosis and the paratyphoses. In the preliminary 

 investigations this was not possible, for the differences be- 

 tween the different diseases had not been recognized when I 

 first undertook this study. The different bacilli, the agents 

 of the paratyphoses, had been studied in the United States but 

 their simultaneous presence in foci of typhosis had not been noted. 

 And in so far as B. pfaffi is concerned, discovered by Pfaff in an 

 epizootic in Vienna, it had not then been incriminated as capable 

 of producing disease in the Gallinaceae. These facts have only 

 been disclosed gradually in the course of these investigations. 



The cultures of bacteriophage used in the immunization ex- 

 periments were prepared in the following manner: 



A culture of B. gallinarum, in Martin bouillon, aged nine or 

 ten hours, that is, very young but showing a definite turbidity, 

 is inoculated with a bacteriophage isolated from the excreta of a 

 recovered chicken and possessing a high virulence for the patho- 

 genic bacillus. After about 12 hours the bacterial lysis is com- 

 pletely finished and the bouillon is perfectly limpid. This cul- 

 ture is filtered through a bougie 1 and distributed into ampoules 

 which are sealed. 



The dose employed for immunization has been in all cases 0.5 

 cc, given subcutaneously. The point of injection is of no im- 

 portance for the slightest local or general reaction has never 

 been observed. 



Experiment I. The following experiments were conducted 

 in 1919 and 1920 in the neighborhood of Agen with the assistance 

 of M. Lambert, D.V.M. 



Barnyard 1. The epizootic began in August, 1919. By October 2, 110 

 of 160 fowls had died. The 50 survivors, of which 5 were already affected, 

 were inoculated with the culture of bacteriophage. The 5 sick chickens 



1 We have seen that whatever may be the virulence of the inoculated 

 bacteriophage one may always obtain secondary cultures in a certain num- 

 ber of tubes. Filtration is thus essential. 



