Aug. 19, 1922 ] SECTION OF MICROBIOLOGY. [MelrcAf Jo3al 



A preliminary remark presents itself. Many authors who have formulated 

 hypotheses as to the nature of the lytic principle have simply taken a particular 

 fact supporting their own point of view and have neglected the whole assembly 

 of experimental facts which renders such a thesis untenable, thereby forgetting 

 that experiment is the final criterion of the truth of a theory. Let us try to 

 resolve the question objectively. 



The choice between the different hypotheses a priori possible to explain 

 the origin of the lytic principle can only be made in accordance with a funda- 

 mental rule of logic — namely, in order that a hypothesis becomes admissible 

 it is necessary that it should explain all the experimental facts and that it is 

 not contradicted by any of them; further, in order that this admissible 

 hypothesis may be considered as being in conformity with the nature of things, 

 it must be proved that all the experimental facts cannot be explained if one 

 abandons or modifies this hypothesis. 



The bacteriolysis produced under the influence of the principle which we 

 have named "bacteriophage" consists in a total dissolution of the microbial 

 body; at the end of this action there remains no visible residue. A total dissolu- 

 tion of a microbial substance can only be due to a transformation or decompo- 

 sition of the proteins of the microbe by proteolytic enzymes. Whence, it may 

 be asked, come these proteolytic enzymes? Four hypotheses may be con- 

 sidered. 



1. The enzymes may be derived from the animal organism which is 

 attacked by the given bacteria. The enzymes would then be the result of a 

 defensive reaction on the part of the organism. 



This is the hypothesis of Kabeshima, Bordet and Ciuca, and Ann Kuttner. 

 Kabeshima- does not specify the particular tissue of the animal from which the 

 enzymes originate; Bordet and Ciuca'^ indicate the leucocytes; Ann Kuttner^ 

 incriminates any tissue. 



2. The enzymes may come from intestinal bacteria as the result of a micro- 

 bial antagonism. For instance, one knows the bacteriolytic action of filtrates 

 of old cultures of B. pyocyaneiis. 



This is the hypothesis of Lisbonne et Carrere, ' for whom the lytic enzymes 

 are secreted by intestinal bacilli such as B. coli, B. proteus, etc. 



3. The enzymes may be secreted by the bacterium itself which undergoes 

 the lysis. These enzymes would therefore be autolysins. 



This is the hypothesis of Weinberg and Aznar.*' Under the action of a 

 cause X the bacteria would acquire the property of secreting autolytic enzymes. 



BaiP had already indicated a similar origin, but his hypothesis was more 

 complicated, and that in order to harmonize his conception with certain 

 experimental facts to which we shall refer later. The bacteria undergoing lysis 

 would become fragmented into filtrable corpuscles (the "splitters" hypothesis 

 of Bail). These corpuscles would secrete enzymes capable of dissolving the 

 bacteria from which they spring. 



With the same view, Otto and Winkler^ have put forward a hypothesis 



