158 THE BACTERIOPHAGE 



peritoneal injection. This experiment is adequate to give a 

 correct interpretation to the accidental finding obtained by Bor- 

 det and Ciuca. 



To summarize: the hypothesis of Bordet and Ciuca dealing 

 with the nature of the bacteriophage is inadmissible, first, because 

 it does not conform to the experimental facts; second, because 

 it is founded upon an erroneous interpretation of an experiment 

 which has not been repeated, and which, even if it had been cor- 

 rect, would not have served as a basis upon which such an hy- 

 pothesis could be founded; third, because invoking as an explana- 

 tion an hereditary phenomenon, it is in formal contradiction to 

 all known facts concerning the hereditary transmission of 

 characters. 



Bruynoghe and his collaborators, who at the beginning of their 

 studies adopted the point of view of Bordet, have since realized 

 that the experimental facts do not harmonize with this hypothesis. 

 They now support the idea of the ultramicrobe, a parasite of the 

 bacteria. 



REFUTATION OF THE HYPOTHESIS OF BAIL 



Bail, in 1921, rejected the hypothesis of Kabeshima and of 

 Bordet. According to him the bacteriophage existed indeed in 

 the form of autonomous masses as I had demonstrated. It con- 

 ducted itself as an ultramicrobe but these particles could only be 

 constituted by the "splitter," that is to say, by particles derived 

 from the lysed bacteria themselves. These organized particles, 

 capable of reproduction under a filtrable form at the expense of 

 the same bacteria, secreted a dissolving diastase. 



Bail adduces in favor of his hypothesis the fact that he has 

 been able to isolate from old cultures a bacteriophage active for 

 the dysentery bacillus of Flexner. The cause of Bail's error is 

 easy to detect. He has dealt with mixed cultures. I have 

 already called attention to the frequency of such cultures and 

 I have indicated their origin. 



The hypothesis of Bail corresponds exactly to the second solu- 

 tion of the second possible hypothesis discussed above. It is 

 needless to repeat the refutation which has been presented. Let 

 us simply recall that the condition sine qua non for the validity 



