410 



THE BACTERIOPHAGE AND ITS BEHAVIOR 



The opsonic action of a bacteriophage suspension manifests itself 

 with such rapidity that it is improbable that the opsonic power can 

 be exercised directly by the protobes. We have seen, in fact, that the 

 bacteria are parasitized only after an appreciable lapse of time, — • 

 ten to twenty minutes. 



An experiment conducted with the following reagents indicates the 

 course of the reaction. Leucocyte suspension, Shiga suspension, and 

 Shiga-bacteriophage suspension are mixed in equal parts. After various 

 periods of incubation drops of the mixture are examined showing results 

 as given in table 53. 



After ten minutes some of the leucocytes are so completely filled with 

 bacilU that counting is impossible. The figure given is a minimum 

 based only on leucocytes in which masses of bacteria were not present 

 to interfere with enumeration. 



The opsonic power must be exerted, not by the bacteriophage pro- 

 tobes themselves, but by some principle which originated during the 

 course of the bacteriophagic process. With the facts now available 

 it is impossible to speak with any degree of assurance as to what the 

 nature of this principle may be.* 



It will be recalled that in an earlier chapter it was stated that by 

 the addition of alcohol to a bacteriophage suspension a precipitate 

 formed, which, in one way or another, involved the bacteriophage 

 protobes. It is of interest to ascertain whether the material thrown 

 down in such a precipitated suspension exerts any opsonic action. 

 The following experiment indicates that the active principle appears, 

 in part at least, in this precipitate. 



Two milHgrams of the alcoholic precipitate of a Shiga-bacteriophage 



* I first advanced the hypothesis'^^ that this principle must be the "lysin" 

 secreted by the bacteriophage protobe. This is indeed possible, but as yet, as 

 I have already said, this can not be proved. 



