58 THE BACTERIOPHAGE AND ITS BEHAVIOR 



Between the smallest quantity of the bacteriophage filtrate capable 

 of provoking bacteriophagy and the amount immediately below this 

 a partial effect is not obtained. The action is complete or there is no 

 activity at all (d'Herelle^i"). 



The smallest quantity of bacteriophage filtrate, of a maximum 

 activity, capable of causing bacteriophagy in a suspension of dysen- 

 tery bacilh, is in the neighborhood of a ten-billionth of a cubic centi- 

 meter (d'Herelle^^"). 



Against the staphylococcus, the smallest quantity to be active is 

 even less; in the experiment given above, about one hundred-biUionth 

 of a cubic centimeter, that is, about 10 cubic micra (d'Herelle). 



Ellis has stated, ^^^ although he presents no protocols to demonstrate 

 the fact, that if two bacterial suspensions are inoculated with the 

 bacteriophage, one with a large quantity, the other with but a small 

 amount, bacteriophagy will not take place equally in both, that is, 

 dissolution will be only partial in the first, and complete in the second 

 case. Even more recently Gohs has reported the following results 

 obtained with a bacteriophage filtrate which had been preserved for 

 a year. When the quantity of filtrate used varied between ^ ^ ^ ^ (^ ^ and 

 1 0,000,000 ^^ ^ *^i*0P bacteriophagy was complete; while when the 

 quantity of filtrate used was from 5 drops to nTi^o ^^ ^ drop the 

 bacteria remained alive. It is indeed difficult to reconcile results of this 

 type with the many experiments which I have made; experiments in 

 which the filtrates have varied in age from those used immediately 

 after preparation to those which had been held for several months and 

 even several years, and in which all of the other conditions contribu- 

 tory to the process of dissolution have been varied in all directions. 

 It would seem that experimental error, something such as an inter- 

 changing of tubes, must have occurred. 



6. INFLUENCE OF PHYSICAL CONDITIONS 



Action of heat 



As a general rule it may be said that bacteriophagy may always 

 take place at that temperature which is the most favorable for the 

 development of the bacterium subjected to the action of the bacterio- 

 phage. This is not equivalent, however, to saying that this temperature 

 is that at which the phenomenon is effected at the greatest rate. More- 

 over, the phenomenon may occur at temperatures very remote from 

 the optimum growth temperature of the bacterium. 



