IMMUNIZATION BY MEANS OF THE BACTERIOPHAGE 257 



tion the bacterial substance is in a state particularly adapted to 

 stimulating the cells of the body which enter into the production 

 of organic immunity. The substance of the bacterial body dis- 

 solves in the medium under the influence of the lysins secreted 

 by the ultramicrobes, but it is not present in the same condition 

 as in the body of the living bacterium, for the bacteriophage does 

 not simply produce a disintegration. This is shown by the fact 

 that the culture medium becomes perfectly limpid, whereas the 

 medium remains cloudy when a simple disintegration takes place. 

 As we have seen in several tests, the destruction of the bacterium 

 by the activities of the lysins — the diastases — is a process of 

 solution. Indeed, it is rather the substances composing the 

 bacterial body which are dissolved. This process is of necessity 

 accompanied by a change in state. It is, then, not proper to 

 speak of the bacterial substance as the principle which provokes 

 the acquisition of immunity; it is in reality the products result- 

 ing from the degradation, under the influences of lysins secreted 

 by the ultramicrobes, of the substances composing the bacterial 

 cells which are effective. 



It is obvious that this is yet only an hypothesis, experiment 

 showing only that the principle which provokes the appearance 

 of immunity is not, under the conditions of the experiment, the 

 bacteriophage considered as a living being. Aside from the 

 dissolved bacterial substance do the diverse principles present 

 in the culture, namely, the bodies of dead ultramicrobes, the 

 lysins, and eventually the anti-lysins, play any part in the pro- 

 duction of immunity? In the present state of these investiga- 

 tions it is impossible to affirm or deny this. 



We have tested the action of temperature on the immunizing 

 element contained in the bacteriolysate. To this end, we have 

 repeated the experiment of the culture of the bacteriophage treated 

 with glycerine, with the difference that the culture has previously 

 been subjected to a temperature of 56°C. maintained for a half 

 hour. Two steers have each received a dose of this culture, 

 heated and glycerinized, corresponding to 0.25 c.c. of the original 

 culture. After forty-five days they were tested, the one with five, 

 the other with fifty, fatal doses of barbone culture. The first re- 

 sisted, the second died. The immunizing principle contained in the 



