54 THE BACTERIOPHAGE 



EFFECT OF ANTISEPTICS UPON LYSIS 



To complete the macroscopic study of the phenomenon it may- 

 be well to consider what effect different substances that may be 

 added to the suspension may have upon the lytic process. 



As we will see with reference to the properties of the bacterio- 

 phage, although it does not present a resistance as marked as 

 some of the ultramicrobes to chemical and physical destructive 

 agents, it is, nevertheless, less susceptible than the majority of 

 cultivable organisms. 



From the particular point of view of lysis, we must recall that 

 the action of antiseptics is complex. The bacteriophage is only 

 able to grow at the expense of living bacteria and all action ex- 

 erted on the bacteria of a suspension are reflected in the phenom- 

 enon of lysis, even if these actions are weak or wholly lacking 

 upon the bacteriophage itself. 



The special resistance of the bacteriophage to antiseptics does 

 not modify the lytic process. 



Antiseptic substances may be introduced into the suspension 

 in amounts sufficiently weak to render their effect on the bac- 

 teria negligible and thus fail to alter the course of the phenomenon. 

 If, on the contrary, the amount of antiseptic is such that it is 

 capable of recognition, the bacteriophage may be unable to multi- 

 ply for lack of normal bacteria and lysis is prevented. In this 

 last case it is easy to see that the conditions of the experiment 

 are the same as if the bacteriophage was placed in the presence of 

 bacteria previously modified by the antiseptic in question. And 

 it has already been shown that under these conditions neither the 

 growth of the bacteriophage nor the lysis resulting therefrom is 

 accomplished. 



The experiment previously presented showed that the bac- 

 teriophage failed to multiply in bouillon suspensions of Shiga con- 

 taining one per cent of sodium fluoride, even though the bacteria 

 remained alive during a period of time amply sufficient for com- 

 plete lysis to be effected in the presence of normal bacteria. 

 Glycerine acts in a different manner. In high concentrations 

 this substance prevents the growth of the bacteria, but its activity 

 is inhibitory rather than strictly antiseptic. 



