BACTERIOLYSIS 57 



The cause for these results is very obvious. The bacteriophage 

 is very sensitive to acidity and with a minimal inoculation the 

 bacteria begin to develop, to attack the sugar, and to render 

 the medium acid before the ultramicrobes are present in ade- 

 quate numbers to effect lysis in the time at their disposal. 



SOLUBLE SUBSTANCES OF THE BACTERIA 



Lysis of the bacteria by the bacteriophage is complete, with- 

 out residue. In the last analysis this lysis can only be in the 

 nature of a diastatic action. No bacterial activity is caused 

 simply by the presence of the organisms as such, but rather by 

 virtue of the secretory products which they elaborate. The ul- 

 tramicrobes necessarily secrete some of these lytic diastases — the 

 lysins — which liquefy the substances constituting the bacterial 

 body. This point will be considered further. The chemical 

 aspect of the reaction has been investigated but little since such 

 studies naturally fall within the field of the chemist. All that 

 may here be stated is that whatever may remain in solution in 

 the clear medium when lysis is complete, it is not protein in 

 nature, as is indicated by the reaction to heating. 



The viscosity of a suspension containing 500,000,000 Shiga 

 bacilli per cubic centimeter differs from that of the bouillon used 

 in preparing the suspension. A volume of bouillon giving nor- 

 mally 100 drops gives but 97 when the suspension is lysed. 



The decomposition of the substances derived from the bacterial 

 bodies continues certainly for some time after the lysis. This 

 can be shown for the Shiga bacteriolysate by the fact that if a 

 rabbit is inoculated with the material immediately after the 

 lysis is completed, it is killed by a dose essentially the same as the 

 minimal lethal dose of the suspension. The toxicity of the bac- 

 teriolysate falls very rapidly; a week after the lysis it is markedly 

 diminished, and in fifteen days the material is practically non- 

 toxic. On the other hand, it is well known that the Shiga endo- 

 toxin is very stable. Obviously then, this endotoxin is rapidly 

 destroyed by the bacteriophage. In a later chapter we shall 

 see that the lysin secreted by the bacteriophage can be obtained 

 by precipitation with alcohol. 



