276 THE BACTERIOPHAGE 



lent bacteriophage also at the same time distribute a resistant 

 bacterium, that is to say, a bacterium particularly apt to nega- 

 tive the defense exercised by the intestinal bacteriophage of the 

 susceptible individuals contaminated by the carrier. 



The observations made in pyelonephritis lead us to believe 

 that the individual affected with a chronic infectious disease is 

 in reality an internal carrier. Here also, the individual enjoys 

 an antitoxic immunity. Nevertheless there is a struggle within 

 the organism between the virulent bacteriophage and the re- 

 sistant bacterium. For while in the intestine the bacterium is 

 henceforth inoffensive and offers no great inconvenience to the 

 host, the presence of a bacterial culture within the tissues is not 

 an indifferent matter because of the inflammatory reactions which 

 it provokes. In addition, phagocytosis is not able to play an 

 active role, for we have seen that bacteria which have acquired 

 a resistance to the bacteriophage are likewise resistant to the 

 phagocytic phenomenon. 



The r61e of the bacteriophage is not confined to the intestine. 

 Whatever may be the infectious disease under consideration, 

 there is always the introduction of the pathogenic bacterium into 

 the intestine, either by the digestive path or by the hepatic route. 

 Thus, the intestinal bacteriophage may come in contact with, 

 and acquire a virulence for, the pathogenic bacterium. Further- 

 more, experiment shows that the bacteriophage may enter the 

 circulation in the case of a septicemia. Hence it may exert its 

 action at any point in the body. 



The action of the bacteriophage manifests itself in still another 

 way. Growing at the expense of the bacteria it dissolves them. 

 The bacterial substance, dissolved and modified under the action 

 of the lysins secreted by the bacteriophage, is in a physical and 

 chemical state particularly suited to act upon the cells of the 

 organism which elaborate the antitoxins. 



Finally, experiment shows that the bacteriophage exercises 

 a preponderant action on phagocytosis. On one side is the 

 fact that the bacteriophage through its lysins possesses an ex- 

 tremely high opsonic power 1 and on the other side, a bacterium 



1 May not the lysins of the bacteriophage and the antilysins of the bac- 

 teria be synonyms for opsonins and aggressins? 



