INTRODUCTION 



This, then, gave a new proof that the dissolving principle actually- 

 regenerated in the course of the action. Further, it demonstrated that 

 the principle was condensed in the form of active particles. 



It is to this principle that I have given the name Bacteriophage; 

 the phenomenon of bacterial solution caused by it being termed Bac- 

 teriophagy. 



With this simple statement of what is meant by the "phenomenon of 

 bacteriophagy" in its broader aspects, let us see if the literature pub- 

 lished prior to my papers on the subject contains data such as might 

 be construed as dealing with the same phenomenon. 



In the first work summarizing my communications on the subject^"^* 

 mention was made particularly of a paper by Hankin dealing with a 

 bactericidal property of the water of the Jumna and of the Ganges 

 rivers. Since the text, "The Bacteriophage, Its Role in Immunity," 

 was published various authors have made a study of the literature 

 and many have sought to discover, in the many studies conducted 

 upon the subject of "bacteriolysis," facts which bear upon the question 

 of bacteriophagy. 



Let us state immediately, and we will return to this question, that 

 the term "lysis," which should always have been appHed strictly in its 

 sense of "a dissolution," has lost in biological usage all significance, 

 and is in fact applied to phenomena which are without any effect upon 

 the vitalitij of the bacterium regarded as undergoing a "bacteriolysis," 

 This is the first source of error, as we shall see. The second cause of 

 error is resident in a faulty logic on the part of those who have examined 

 these earher communications. Bacteriolysis, even true bacteriolysis, 

 resulting in a dissolution of the bacterial cell, is not a phenomenon 

 with but a single cause. Bacteriolysis is a syndrome, one might say, 

 which can be provoked by different causes or diverse agents. A 

 number of varieties of bacteria undergo dissolution when placed in 

 water saturated with ether. May one speak here of bacteriophagy? 

 The pneumococcus, like some other fragile bacteria, is dissolved within 

 a few days if it is allowed to remain in the liquid culture medium where 

 it has developed. Is this bacteriophagy? Certainly not. For, in 

 neither case is the dissolution accompanied by the very special charac- 

 teristics which delimit bacteriophagy. 



Bacteriophagy, as we will see in the course of this text, is a phe- 

 nomenon presenting very distinctive characteristics, such as permit it 



* Referring to the bibliographic material appended to the text. 



