BACTERIOPHAGE AS AN ANTIGEN 



401 



their experiments with a bacteriophage of maximum virulence, I found 

 it necessary, in order to obtain an inhibition of bacteriophagy, to add 

 to the bacterial suspension inoculated with the bacteriophage a quan- 

 tity of antibacterial serum far greater than that used by these authors. 

 I will cite one of these experiments illustrating the effects observed. 

 All gave comparable results. 



To tubes containing 10 cc. of bouillon (pH 7.8) 16 drops of a Shiga- 

 bacteriophage suspension were added, along with variable quantities 

 of an anti-Shiga serum, agglutinating in a dilution of 1:6500. After 

 incubation for 1 hour at 37°C. the tubes were planted with 3 drops of 



a 24-hour bouillon culture of Shiga bacilli. The results were as shown 

 in table 51. 



From a titration of this type it is obvious that the antibacterial 

 serum has an inhibitory effect upon bacteriophagy, but it also shows, 

 at least when working with a very virulent bacteriophage, that it is 

 necessary that it be added to a high concentration. As a matter of 

 fact, additional experiments have shown that the effect of an anti- 

 bacterial serum becomes more outspoken as the bacteriophage used 

 is of lower virulence. 



As mentioned above, da Costa Cruz^^^ presents data showing the 



