THE MECHANISM OF BACTERIOPHAGY 115 



three, or sometimes several, stained "discharges." The material 

 gives a definite impression that a portion of the contents of the bac- 

 terium have escaped by means of one, or of several, apertures. 



This observation suggests that the wall of the bacterial cell (formed 

 beyond doubt of condensed protoplasm) has been perforated by one, 

 or several, bacteriophage corpuscles, and that the avenue of entrance 

 has remained open. 



However this may be, the single fact that the phenomenon of rup- 

 ture is "explosive" in nature shows that the bacteriophage corpuscle 

 certainly penetrates to the interior of the bacterium, and that it is in 

 this location that the multiphcation takes place. 



4. MULTIPLICATION OF THE BACTERIOPHAGE CORPUSCLE 



At the very beginning of this section I believe it wise to state once 

 more that when I cite an illustrative experiment it is not equivalent 

 to stating that the rate of the reaction of all experiments which may 

 be carried out upon the same subject must be identical. Such an 

 erroneous deduction has been reached by a number of authors. For 

 example, the experiment presented in the second section of the present 

 chapter, and to which we will return, shows that the first increment in 

 the bacteriophage was in a ratio of 18:1. This numerical ratio holds 

 necessarily for this experiment only. In other cases it is possible to 

 have ratios of increase anywhere between 6:1 and 60:1. Everything 

 depends upon the conditions of the experiment, chiefly upon the "viru- 

 lence" of the bacteriophage with which one is working, 



Bacteriophagy always takes place in the same manner; the sequence 

 of events is always the same. The bacteriophage corpuscle must in- 

 variably become fixed to the bacterium to exercise its action. Destruc- 

 tion of the bacterium is always accomphshed by bursting. The bac- 

 teriophage corpuscles always multiply within the bacterial cell and 

 are always liberated with the rupture of this cell. But the time 

 required for the fixation to take place, the time necessary for the bac- 

 terium to undergo rupture, the number of young bacteriophage cor- 

 puscles developing within the bacterium to be liberated with its 

 rupture, all vary in each particular case, according to a multitude of 

 conditions which vary from one experiment to another. 



Having again emphasized this, let us consider the manner in which 

 multiplication of the bacteriophage corpuscle takes place, and the 

 nature of the conditions which exercise an effect upon their develop- 

 ment. 



