COCCI 97 



dead cells are used as nutrients by the living organism. The mechanism 

 of the action was variously explained by a change in the fH value of 

 the medium or in the oxidation-reduction potential or by a direct enzy- 

 matic effect. In some cases thermolabile, filterable substances were dem- 

 onstrated (141, 26Sy 36^, 580). These substances have been considered 

 either as autotoxins (141) or as proteolytic enzymes (683). According 

 to Schilling and Califano (799, 800), the filtrate of E. colt depressed 

 only the dysentery organism of Shiga. From a bouillon culture of E. 

 coliy Gundel (370) isolated thermostable lipoids capable of bringing 

 about the lysis of the colon bacteria and other bacteria. The antagonistic 

 relations between E. coli and V. comma have been well established, the 

 cholera organism also possessing antagonistic properties (307, 480). 



The typhoid organism is also capable of exerting an antagonistic ac- 

 tion against itself, as well as against Ps. fuorescens (311) and E. coli 

 (323). Similar antagonistic effects (224) have been obtained against 

 various other bacteria, including B. anthracis (823, 898). The nature 

 of the action is not clearly understood. Salmonella -paratyphi possesses 

 antagonistic properties against E. coli (453), B. anthracis (898), P. 

 pestis (246), and various other bacteria. 



It may be of interest to record here that E. coli isolated from persons 

 affected by rectal cancer are able to convert substances related to bile 

 acids to carcenogenic bodies. The possibility of synthesis of such sub- 

 stances has also been suggested (186). 



COCCI 



Numerous cocci have been found to possess antagonistic properties 

 against other bacteria. Doehle (178) first demonstrated in 1889 that 

 streptococci are able to antagonize B. anthracis y especially on solid 

 media. Similar action was exerted against diphtheria bacteria (52, 71, 

 131? 799j 800), a phenomenon apparently not correlated with the 

 hemolytic properties or the virulence of the antagonist. Further studies 

 established the effect of various streptococci against anthrax (233, ^dG^ 

 676). According to Cantani ( 105) this effect is more pronounced in liq- 

 uid than in solid media, and is highly specific as regards the strain. S. 

 pyogenes was shown to be antagonistic, in vivo, to B. anthracis and to 



