538 THE BACTERIOPHAGE AND ITS BEHAVIOR 



ularly in connection with protection against bacillary dysentery, and 

 it seems that such a course is the more logical since, as we shall see, the 

 administration of bacteriophage suspensions is being applied on a 

 large scale in the specific therapy of this disease. 



Experiments have been carried out in three very different infectious 

 diseases: 



a. One an infectious disease in which the portal of entry of the causa- 

 tive agent is the intestinal tract (avian typhosis) ; 



b. One a septicemic disease (barbone of the buffalo) ; 



c. One a toxic disease (injection of the rabbit with Shiga bacilh). 

 The experiments have been carried out under different environmental 



conditions : 



a. In an environment contaminated by the infecting agent (avian 

 typhosis) ; 



b. In an environment free of contamination (barbone). 



The results obtained with these differing diseases, under these varied 

 circumstances permit the following conclusions: 



The experiments made upon barbone of the buffalo in an uncon- 

 taminated environment show that after the injection of a bacterio- 

 phage suspension there is an initial, and very short, period of im- 

 munity,- — 24: to 48 hours, — ^followed by a period in which the animal has 

 returned to its normal susceptibihty, the length of which is increased 

 as the dose of suspension given was the greater. After a variable 

 time,- — 20 to 30 days after doses of 1 to 2 cc. in the buffalo, — ^an im- 

 munity is established which borders on the refractory state (d'Herelle 

 and Le Louet^-^) . This second period of immunity persists for at least 

 14 months (Le Louet''"'^). 



The first period of immunity is "exogenous" in nature. It is due to 

 the presence in the body of bacteriophage protobes virulent for the 

 pathogenic bacterium. In a contaminated environment this period of 

 exogenous immunity persists as long as re-infections occur; re-infections 

 which permit the protobes to multiply and maintain themselves. In an 

 uncontaminated environment the bacteriophage is unable to multiply 

 because of a lack of susceptible bacteria. Elimination from the body 

 is rapid, and the exogenous immunity ceases immediately after this 

 elimination is complete. 



The second period of immunity, is certainly endogenous.* It is the 



* As I use the terms, "exogenous immunity" is that which is due to the presence 

 of the foreign principle in the body, — as the bacteriophage corpuscle itself, — 

 "endogenous immunity" is that which results from a reaction of the body it- 



Self.311.321,349 



