386 



THE BACTERIOPHAGE AND ITS BEHAVIOR 



depended upon real differences in the antigenic property of the different 

 races of the bacteriophage. 



We have already mentioned that Prausnitz^^'' has shown that it is 

 possible, by adaptation, to render a bacteriophage resistant to the 

 action of its homologous antiserum. Bruynoghe and Wagemans^^^ 

 confirmed this fact, but by a different procedure. They prepared 

 three antisera of unequal neutralizing values for a single Coli-bacterio- 

 phage. Three successive passages were made with this bacteriophage, 

 the first in media containing the least active serum, the second in 

 media with the shghtly more active serum, and the third in media 

 containing the most active serum. After these three passages they 

 found that the bacteriophage thus adapted caused a normal bacteri- 



* The figures marked with an asterisk were obtained by counting a segment of 

 a plate, using a Wolfhiigel apparatus. 



ophagy in the presence of quantities of a homologous antiserum which 

 completely inhibited the action of the same unadapted bacteriophage. 

 They found further that when the bacteriophage has become resist- 

 ant, after having undergone passages in a normal medium sufficient 

 in number to insure that all traces of the serum have been eliminated, 

 it caused the development of "anti" properties when used as an antigen 

 more active for the original unadapted bacteriophage than for the 

 adapted bacteriophage — the corpuscles used in the immunization of 

 the animals. 



3. THE COURSE OF THE ACTION OF THE ANTIBACTERIOPHAGIC SERUM 



The following experiment of Prausnitz^^^ shows something of the 

 nature of the process of inactivation of bacteriophage corpuscles by an 



