BACTERIOPHAGY IN A FLUID MEDIUM 51 



example, discussion must be reserved for a later chapter. For the 

 time being let us simply treat of the macroscopic appearance of the 

 phenomenon; let us describe only those things that can actually be 

 seen. 



It may be well, however, to consider at once the significance of the 

 distinction made by certain authors between what they term a "proc- 

 ess of inhibition" and a "process of bacteriolysis." This distinction 

 is based upon whether the bacteriophage principle is inoculated into 

 a medium simply seeded with susceptible bacteria or whether it is 

 introduced into a cloudy suspension of these bacteria. Such a differen- 

 tiation implies that in the first case growth does not occur, the bacterio- 

 phage seems to "inhibit" multiplication, while in the second case the 

 turbid medium becomes perfectly clear after the complete dissolution 

 of the bacterial bodies. 



As a matter of fact, it is difficult to conceive how the two cases can 

 possibly be considered as distinct. For whatever may be the actual 

 number of bacteria present in a medium the phenomenon is exactly 

 the same, the course of the reaction is the same, and the end result, a 

 complete dissolution of the bacteria present, is the same. It is very 

 obvious that if the number of bacteria is so small that the medium 

 appears clear from the beginning (as in a simple seeding) the medium 

 will show no change, it will remain clear, for the few bacteria present 

 will be dissolved. If, on the contrary, because of the enormous num- 

 ber of bacteria present, the medium was clouded or turbid at the out- 

 set, that is, at the time when the bacteriophage was inoculated, it 

 becomes limpid only when all of the bacteria have been dissolved. In 

 one case, just as in the other, the same phenomenon has taken place, 

 the action of the bacteriophage has been of the same nature. A con- 

 sideration of the different cases which we will present will leave no 

 doubt upon this point; a basic and vahd distinction between an "in- 

 hibition" and a "bacteriolysis" is impossible. Under both conditions 

 as to quantity the phenomenon is qualitatively the same. 



Limits of baderiophagy 



Let us repeat once more that all of the experiments presented in this 

 first chapter deal with the typical phenomenon of bacteriophagy, that 

 is, with that which takes place through the intervention of an extremely 

 active bacteriophage. To enter upon a study of bacteriophagy using 

 races of the principle having but shght activity is simply to wiUfuUy 

 invite difficulties, both in experimental procedure and in interpretation. 



