J. ERONFENBRENNER 



547 



terial subjected to analysis consisted of ordinary culture medium too rich in various 

 products of hydrolysis of protein to permit the detection of a possibly small increase 

 due to the hydrolysis of bacteria. The lysis of bacteria in a synthetic medium, devoid 

 of all protein, gave unmistakable evidence of hydrolysis of bacterial protein.' 



In the light of these experiments, the clearing of bacterial cultures in the presence 

 of bacteriophage seems to be due to hydrolysis of bacteria. The active agent (bac- 



F1G.7. — ^Advanced stage of disintegration of the cytoplasm with ectoplasm intact. Stained by 

 carbol-fuchsin, followed by methylene blue. Photographed through an orange filter. IMagnification 

 X 1,500. 



Fig. 8. — Photograph of a drawing, showing distribution of chromatin granules in swollen bac- 

 teria. Preparation stained by carbol methylene blue, followed by fuchsin. IMagnification X 1,000. 



teriophage) plays no part in the actual dissolution. The dissolution is the result of 

 intracellular digestion brought about by normal endoferments. Just how these en- 

 doferments become activated remains unknown at present.^ The increase of osmotic 

 pressure within the cells, following the beginning of digestion of the cytoplasm, leads 

 to intake of water which probably facilitates further digestion,^ and progressive swell- 

 ing. The degree of swelling of individual bacteria depends on the ability of the mem- 

 brane to withstand the pressure. When the limit of turgescence of a given cell mem- 

 brane is reached, it ruptures and the predigested intracellular contents are dissolved 

 in the medium. 



The phenomenon of transmissible lysis can thus be divided into two stages. The 

 early stage depends on the presence of the phage, which stimulates bacteria. The 



^ Bronfenbrenner, J., and Hetler, D.: Jour. Exper. Med. (In press.) 



^ It has been suggested by Warburg (Warburg, O. : Zlschr. f. pliy. Cltemie, 66, 305. 1910), how- 

 ever, that profound changes may be initiated in a living cell by toxic substances, even in cases where 

 these substances do not penetrate the cell but act on the membrane onl\-. 



3 Northrop, J. H.: /. General Physiol., 4, 245. 1922: Hussey, R. G., and Northrop, J. H.: ibid., 

 5. 335- 1923- 



