388 



THE BACTERIOPHAGE AND ITS BEHAVIOR 



mixture was added to suspensions of the different bacteria for which 

 the races of bacteriophage were virulent.* 



Table 46 indicates the comparative results obtained with the bac- 

 teriophage-antiserum mixture and the bacteriophage alone. 



B. A rabbit received 7 injections of bacteriophage F-2. Each in- 

 jection was 2 cc; the intervals between injections, 8 days. This race 

 caused bacteriophagy : 



with B. dysenteriae Flexner at 1 • 10~^ 

 with B. dysenteriae Hiss at 1 • 10~^ 



and was without action on B. dysenteriae Shiga and B. typhosus. 



Determinations made as above (with the anti-K serum) gave the 

 result shown in table 47. 



C. A rabbit received 15 injections, at intervals of 8 days of bac- 

 teriophage Y. Two cubic centimeters were given at each injection 

 and the rabbit was bled 10 days after the last injection. Table 48 

 gives the results of the tests of neutrahzing action of the antiserum. 



From these experiments it appears: 



First, that in general, an antiserum for the Flexner-bacteriophage 

 inactivates the virulence of the Flexner-bacteriophage for the Flexner 

 bacillus (and for the Hiss bacillus, a very closely related, if not identical 

 organism) . This is true for a maj ority of the races of the bacteriophage. 



* The results in the tables are expressed according to the scheme of notation of 

 Otto; the various symbols meaning: 



= absence of plaques when spread on agar. 

 ± = the agar medium shows a few scattered plaques. 

 -fl and +2 = the plaques are confluent, the figure indicating the relative 

 number. 

 +3 — isolated bacterial colonies. 

 +4 = the agar medium shows no growth whatever. 



