UBIQUITY OP BACTERIOPHAGE 433 



2. Bacteriophage from the horse {Alexandria) 

 The original filtrate showed virulences as follows : 



3. Bacteriophage from a chicken {Alexandria) 



The intestinal bacteriophage of the original filtrate showed the follow- 

 ing virulences : 



B. dysenteriae Shiga + + + + 



B. dysenteriae Flexner -|- + + 



B. dysenteriae Hiss + + + + 



B. paratyphosus B + + + + 



B. coli + + 

 With this bacteriophage passages were made with B. paratyphosus B, 

 and following the purification, the virulences of the three plaques 

 proved to be : 



In this case there seem to have been two races in the original filtrate. 

 In order to be certain of this I returned to the original filtrate, which 



