Aug. 19, 1922 ] SECTION OF MICROBIOLOGY. [ ulZ^Zl.. 



moment there are no longer any living bacteria in the emulsion— it is a pure culture 

 of the ultramicroscopic bacteriophagic corpuscles. The bacteriophagic power of such 

 a lysed culture remains at its maximum level during many weeks— it is practically 

 "fixed." 



The foregoing experiments show that the lytic enzymes are originated by 

 ultramicroscopic corpuscles which multiply and reproduce themselves. Hence 

 those hypotheses explaining the phenomenon as being due to a soluble auto- 

 lytic enzyme become eliminated. 



Of all the hypotheses put forward, only that of Bail, and perhaps that of 

 Otto and Winkler, could not be incompatible with these experiments, since 

 they suppose that the element which secretes the lytic enzymes can be 

 furnished by ultra-microscopic corpuscles, but derived from the bacteria. It 

 is difficult to reconcile these hypotheses with the fact that the bacteriophagic 

 action is not specific, and that the same strain of bacteriophage can dissolve 

 bacteria of different species. Indeed, if one can understand how a principle 

 originated by a species of bacteria can provoke the formation of a similar 

 principle in a culture of the same bacterial species, it is hard to admit how this 

 principle could provoke the formation of the bacteriophagic principle in a 

 culture of a different bacterial species. Besides, these two hypotheses are 

 rendered untenable by the following fact. 



THrao Fact: All bacteriophagic ultramicroscopic corpuscles, grown at the 

 expense of any bacterial species, constitute one and the same antigen. 



I have up to the present isolated various strains of bacteriophage active 

 towards different bacteria: B. typhosus, B. paratyphosus A and B, B. dysen- 

 teriae (Shiga, Flexner, Hiss), B.coli, B.pestis, B.proteus, B. gallinarum, bac- 

 teria of haemon-hagic septicaemias, staphylococcus, etc. 



We have seen above what constitutes a culture of the ultramicroscopic 

 bacteriophagic corpuscles. Inoculate an emulsion of B. dysenteriae with a 

 filtrate containing an active bacteriophage towards this bacterium; after a few 

 hours the medium becomes limpid, the bacilli are dissolved, and the bacterio- 

 phage corpuscles have multiplied; the culture of the bacteria has become a 

 culture of antidysenteric bacteriophage. Similarly, a culture of B. pestis 

 dissolved under the action of the bacteriophagic principle (isolated from the 

 intestinal contents of a convalescent from bubonic plague) becomes a culture 

 of antipestic bacteriophage. And so on for any other microbe. 



One knows that the serum of a rabbit prepared by injections of B. dysen- 

 teriae contains an amboceptor towards B. dysenteriae, but does not contain any 

 amboceptor towards any other bacteria— for example, B. pestis. 



Now prepare a rabbit with a culture of B. dysenteriae dissolved by bac- 

 teriophagic action; one verifies that its serum does not contain any amboceptor 

 towards normal B. pestis, but contains an amboceptor for B. pestis dissolved 

 by the action of the bacteriophage. And this is true for no matter what bac- 

 terial species; the serum of an animal prepared by a culture of any bacterial 

 species dissolved by bacteriophage contains an amboceptor which fixes itself 

 on any other bacteriophaged culture. Hence the amboceptor is specifically 



