370 THE BACTERIOPHAGE AND ITS BEHAVIOR 



directed toward a bacterium and a contact is established. The protobe 

 then penetrates the peripheral zone of the bacterium (the opening made 

 remaining open) and multipHes within the bacterial protoplasm, forming 

 a colony composed of a number of elements varying with the conditions 

 of the moment. When the process of multiphcation is completed the 

 parasitized bacterium ruptures and undergoes a sudden dissolution. 

 This liberates the young protobes, and each of the latter is then ready 

 to repeat the process and parasitize the nearest bacterium. Thus 

 the cycle begins anew, and continues until all of the bacteria present 

 in the media have disappeared.* 



How is this dissolution of the bacterial body brought about? 



A priori, there are three possible hypotheses: 



I. The bacteriophage protobe may itself act Hke an enzyme. In 

 such a case it must be, in short, an enzyme of which each granule is 

 capable of assimilation and of reproduction at the expense of the sub- 

 stances upon which it acts. This hypothesis is hardly probable, for 

 the bacteriophage corpuscles, although minute, have a relatively large 

 volume,^ — 2O111X — much larger than the granules of the known ferments. 



II. The bacteriophage induces the bacterium to produce autolytic 

 enzymes. The meaning of the first hypothesis was self-evident; this 

 second one requires a little explanation. 



Autolysis in a confined medium,^ — the method of Jaumain,"? — of 

 which I have spoken above, shows us that under certain pecuhar phys- 

 ical conditions, but without the intervention of any foreign substance, 

 a non-spore-bearing bacterium may quicldy produce autolysins capable 

 of dissolving the bacterial body completely. The phenomenon is com- 

 parable to that which takes place in bacteriophagy, except that it is 

 not transmissible in series. A permanent cause, persisting despite 

 successive dilutions, is lacking. 



For some time we have known that a great many spore-forming bac- 

 teria completely disappear after the formation of the spore. In this 

 connection I have studied B. anihracis, an organism admirably suited 

 and of particular interest from this point of view inasmuch as it is easy 

 to obtain asporogenous varieties. It is found that, although with the 

 sporulating races a dissolution of the vegetative forms in the medium 

 may readily be observed after the formation of the spore, a natural 

 spontaneous autolysis is never observed with the homologous asporogen- 

 ous races. The autolysis is, therefore, predicated upon the presence 

 of the spore within the interior of the bacterium. 



* This is conditioned, naturally, upon the bacteriophage being sufficiently 

 virulent. 



