70 THE BACTERIOPHAGE AND ITS BEHAVIOR 



Sugars 



Asheshov" has shown that with certain races of the bacteriophage 

 (one only among those which he studied) bacteriophagy takes place 

 more rapidly if glucose is added to the medium. With this particular 

 race, active against B. dysenteriae Flexner, dissolution of the bacteria 

 was complete after 4| hours in the presence of glucose, while in or- 

 dinary bouillon it was only partial after a period of 7 hours. Further 

 studying the reaction with this particular race he concluded that the 

 acceleration must be due to the fact that B. dysenteriae in fermenting 

 the glucose rendered the reaction acid. This, then, represents a 

 particular distinctive race, with which the optimum activity occurs in 

 a medium of increasing acidity. We will return to this observation. 



Seiser^^'' has suggested that the addition of glucose to the medium 

 favors bacteriophagy in all cases, but in agreement with Asheshov, 

 I have not found this to be true. Indeed, it appears that the situation 

 is quite the reverse. 



The experiments which I have performed during the past few years 

 have not modified my original conclusions in this respect. The addi- 

 tion of non-fermentable sugars* to a bacterial suspension subjected 

 to the action of the bacteriophage has no effect upon the phenomenon. 

 In the case of fermentable sugars, if the inoculation of bacteriophage 

 has been massive, bacteriophagy takes place normally. If the inocu- 

 lation has been weak (or if the race of bacteriophage is of low activity) 

 bacteriophagy is incomplete or does not occur, the result depending 

 upon the amount inoculated. The reason for such an effect is obvious. 

 We already know that the great majority of races of the bacteriophage 

 are very sensitive to the action of free H ions. With a minimal inocu- 

 lation of bacteriophage the bacteria start to grow, they attack the 

 sugars, and the medium becomes acid before the quantity of the bacterio- 

 phage, regenerating in the course of the action, is sufficient to effect 

 a dissolution of the bacteria in the tmie available. In a word, the 

 limit of acidity incompatible with the phenomenon is reached before 

 the bacteriophage is able to become effective (d'Herelle^-^- 



Salts 



In previously reported experunents^-^ I have shown that calcium 

 chloride interferes with the bacteriophagy of Shiga bacilli; that potas- 



* This holds only when the quantity of sugar added is not sufficiently high to 

 materially modify the viscosity of the medium. We have already seen that an 

 increase in viscosity retards bacteriophagy. 



