CHAPTER VI 



The Nature of the Bacteriophage 



Nature of the Bacteriophage. The Number of Possible Hypotheses. 

 Experimental Proofs of the Living Nature of the Bacteriophage. Refu- 

 tation of the Hypothesis of Kabeshima. Refutation of the Hypothesis 

 of Bordet andCiuca. Refutation of the Hypothesis of Bail. Refutation 

 of the Hypothesis of Salimbeni. Conclusions. 



THE nature of the bacteriophage 



All of the facts which have been recognized up to the present 

 time and which have been recorded in the preceding chapters 

 have been confirmed by all authors who have investigated the 

 question. The phenomena themselves have never been the sub- 

 ject of controversy, and because of their definiteness, it might be 

 said because of their violence, and because of the facility with 

 which they can be reproduced, they can not be controverted. 



The discovery of the bacteriophage was associated with a study 

 of a disease of locusts, in which I for the first time noted in the 

 intestine of the insects which resisted the infection a principle 

 antagonistic to the action of the pathogenic cocco-bacillus; a 

 principle which could be demonstrated by its effects but which 

 of itself could not be isolated. With this suggestive observation 

 as a basis, I systematically sought for a comparable principle in 

 the intestinal contents of patients with enteric infections. Finally, 

 during the year 1915, in studying an epidemic of dysentery which 

 prevailed in a squadron of cavalry stationed in the neighborhood 

 of Paris, I noted the phenomenon of plaques in the cultures on 

 agar tubes. Shortly after, from the stools of a patient under 

 treatment in the Pasteur Hospital I was able to isolate by filtra- 

 tion the antagonistic principle. The study was continued dur- 

 ing the rare moments which my duties as Chief of the Laboratory 

 Service for the Preparation of Vaccines permitted. (More than 

 twenty million doses of vaccines were furnished by the Service 

 to the Allied Armies during the war.) I tried particularly to 



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