56 THE BACTERIOPHAGE 



Tube 3. The Shiga bacilli, in the same concentration, are suspended in 

 bouillon with 60 per cent of glycerine. Portions of this suspension are 

 inoculated with various amounts of the bacteriophage culture, as follows: 



a. With 0.5 cc. of the bacteriophage culture. With this amount lysis 

 is complete in eight hours. 



6. With 0. 02 cc. of the bacteriophage culture. Complete lysis is obtained 

 in nine hours. 



c. With 0.0001 cc. of the bacteriophage culture. No lysis results. The 

 ultramicrobes inoculated, too few in number, have not had time to develop 

 before the bacilli are dead. A control suspension, without the bacterio- 

 phage, gave positive cultures only up to the 18th hour. 



From this it appears that in glycerine broth the bacilli remain 

 normally susceptible to attack by the bacteriophage just as long 

 as they are living. 



Although the bacteria die when suspended in the glycerine 

 medium it can not be assumed that the glycerine acts as a true 

 antiseptic, that is, that it modifies the bacterial protoplasm. No 

 one would contend that sodium chloride in weak concentration is 

 an antiseptic despite the fact that non-spore-forming bacteria 

 suspended in normal saline survive for but a very short time: 

 twenty-four to forty-eight hours in the case of the Shiga bacillus. 



The experiments on lysis in the glycerinated media are, more- 

 over, of great interest in that glycerine, in very high concentra- 

 tions, sterilizes cultures of the bacteriophage. 



Substances without action on the bacterial cells are, in general, 

 without influence on lysis. This, for example, is the case with 

 normal serum, ascitic fluid, urine, and 2.5 per cent sodium chloride. 

 Calcium chloride, on the other hand, has a very marked inhibi- 

 tory effect, and potassium chlorate delays lysis. In low concen- 

 trations magnesium sulfate and the phosphates of sodium and 

 potassium favor lysis. This is particularly observed in the case 

 of strains of the bacteriophage of feeble activity. 



When sugars which are not fermented by the bacterium against 

 which the bacteriophage is active are added to the suspension 

 lysis is not modified. The addition of fermentable sugars is 

 without effect if the inoculation of the bacteriophage is massive, 

 but if the inoculation is weak lysis does not occur or remains 

 incomplete, depending upon the amount inoculated. 



