282 THE BACTERIOPHAGE 



koff and his collaborators affirm that phagocytosis plays a 

 capital role. That the elimination of bacteria is effected by 

 phagocytosis, once organic immunity is established, would appear 

 to be the proper interpretation. 



However, in the one or in the other case, the bacteriophage 

 manifests its action. Its activity is not naturally limited to the 

 bacteria pathogenic for a given animal; it is exercised without 

 distinction against bacteria pathogenic and saprophytic, in all 

 circumstances, and in all animals. Even if, in the immune 

 animal, the bacteriophage should remain inert, the bacteria would 

 none the less be eliminated by phagocytosis. 



What then is the role of the bacteriophage in immunity? The 

 defense of the susceptible individual exposed to infection, and the 

 protection of the organism in the course of natural disease. Par- 

 asitic of bacteria, the bacteriophage intervenes directly to destroy 

 the pathogenic bacteria which venture to invade the organism; 

 secreting lysins endowed with a powerful opsonic action, it ren- 

 ders possible the education of the phagocyte and introduces the 

 establishment of organic antibacterial immunity; dissolving the 

 bacteria, it transforms the bacterial substance and places it in a 

 physical and chemical state where it can stimulate the cells of 

 the body which produce the antitoxic antibodies, it introduces 

 thus, the establishment of organic antitoxic immunity. 



In other terms, the bacteriophage plays a preponderating role 

 in all the phenomena of immunity which are accomplished in a 

 susceptible individual. As a result of its presence it follows that, 

 although exposed to infection it is possible to remain unharmed; 

 and although sick, it is possible to recover. 



