

CHAPTER II 

 The Bacteriophage in the Healthy Individual 



The Bacteriophage in Man. The Bacteriophage in the Horse. The 

 Bacteriophage in Fowls. The Bacteriophage in Diverse Animals. 

 Conclusions. 



The experiments conducted on patients and on healthy in- 

 ividuals exposed to infection have shown that a resistance to 

 the infectious agent accompanies the presence in the intestine 

 of an ultramicrobial bacteriophage possessing a virulence for 

 the causative bacterium. On the other hand, as I have shown in 

 Part I of this monograph, there is but a single species of bacterio- 

 phage, capable, by adaptation, of acquiring virulence for the 

 diverse bacteria which it attacks. 1 



These facts being true, a question quite naturally arises. Does 

 this bacteriophage which acquires virulence for diverse patho- 

 genic bacteria make its appearance only at the exact moment 

 when it is needed? Or is it, indeed, a normal inhabitant of the 

 intestinal canal? Examination of the feces of numerous individ- 

 uals belonging to very varied species permits an answer to this 

 question. 



the bacteriophage in healthy men 



Variations in the virulence of the intestinal bacteriophage in 

 healthy men have been followed. To this end, in a first series 

 of experiments, specimens of the stool were collected every fifteen 

 days. The study has been limited to testing the activity of the 

 ultramicrobe against the following bacterial species: B. coli, 

 B. dysenteriae Shiga, B. dysenteriae Flexner, B. dysenteriae Hiss. 

 B. typhosus, B. paratyphosus A, and B. paratyphosus B. Later 



1 The possibility of a germ being virulent for a great number of different 

 beings is not an exception peculiar to the bacteriophage. It is only neces- 

 sary to mention B. tuberculosis, to which but few animals are insusceptible. 



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