128 THE BACTERIOPHAGE 



Here it is impossible to calculate the opsonic indices, since no 

 phagocytosis occurred in the control mixture. The indices are 

 infinity. 



The bacterium of barbone which resists the action of the bac- 

 teriophage is also resistant to phagocytosis. 



Experiment XXXIX. Prepare a mixture of one-third leucocytic sus- 

 pension, one-third of the same culture of anti-barbone bacteriophage as 

 that used in the preceding experiment, and one-third of a suspension of 

 the bacterium of barbone resistant to lysis. After fifteen minutes at 37°C. 

 100 leucocytes have ingested 3 bacteria, that is to say, 90 times less than 

 with normal bacteria. 



The strain of anti-dysentery bacteriophage employed in the 

 experiments previously described manifests a definite, although 

 feeble, lytic action against B. typhosus. The following experi- 

 ments show that it also exerts a definite opsonic action on this 

 bacillus. 



Experiment XL. 1. Mix equal parts of bouillon, leucocyte suspension, 

 and B. typhosus suspension. 



After fifteen minutes at 38°C. 100 leucocytes have phagocytized 68 

 bacilli. The opsonic index is 1 . 



2. Mix equal parts of anti-Shiga bacteriophage culture, leucocyte sus- 

 pension, and typhoid suspension. 



After fifteen minutes 100 leucocytes have ingested 203 bacilli. Opsonic 

 index = 3. 



3. Mix equal parts of leucocyte suspension, typhoid suspension and 

 lysin solution (the same one as that employed in the experiments with the 

 dysentery bacillus) . 



After fifteen minutes 100 leucocytes have ingested 109 bacilli. Opsonic 

 index = 1.6. 



The lysin possesses a property which is indeed peculiar. When 

 used in the complement fixation reaction as an antibody it func- 

 tions as an amboceptor. The experiment cited below is taken 

 from among many others which gave identical results. 



Experiment XLI. Antigen: This is prepared according to the method 

 of Maurice Nicolle. One loopful of an agar culture of B. dysenteriae Shiga 

 is suspended in 4 cc. of saline. This suspension, heated at 100°C. for five 

 minutes, then cooled, serves as antigen. 



Antibody: An alcohol precipitate of a culture of anti-Shiga bacteriophage 

 taken into solution in a quantity of saline equal to the original volume of 

 the culture acts as antibody. 



