J. BRONFEN BRENNER 531 



to bacteriophage, there are present homologous, live bacteria, seems to have no di- 

 rect bearing on this question. Even if lysis of dead bacteria were due directly to lytic 

 activity of the phage (which was shown by the writer not to be the case),' so long as 

 live bacteria are present the increase of phage could not be attributed directly to as- 

 similation by phage of dead bacteria. 



Apart from the question of the nature of the substratum supposedly utilized by 

 the Bacteriophagurn intestinale, Asheshov attempted to demonstrate its autonomous 

 metabolic activity by "vaccinating" animals and susceptible bacteria with "ultra- 

 sterile" filtrates, presumably free from bacteriophage, but supposedly containing the 

 products of its metabolic activity.^ In these experiments, as in those quoted above^ 

 and performed in confirmation of experiments by Wollman, Asheshov employed 

 the plaque method for controlling "ultra-sterility" (absence of active phage) in his 

 filtrates. Because of the interference by agar, it is conceivable in the light of our ex- 

 perience^ that he might have missed a small amount of phage in the filtrate, particu- 

 larly as the phage which has been put through a collodion membrane tends to yield 

 extremely minute plaques. ^ This assumption seems validated also by Wollman, who 

 attributes his earlier erroneous conclusion,^' concerning the impermeal^ility of col- 

 lodion to phage, to his failure to detect by the plaque method minute amounts of 

 phage present in the filtrate." In view of these considerations, the findings of Ashe- 

 shov are probably due to the presence of small amounts of active phage in his 

 supposedly "ultra-sterile" filtrates and cannot, without further evidence, be con- 

 sidered as proof of independent metabolism of the Bacteriophagum intestinale. 



It seems to be generally accepted at present that the increase in the concentra- 

 tion of the active agent in the solution takes place exclusively in the presence of live 

 and actively multiplying susceptible bacteria. Therefore the question of the pos- 

 sibility of independent assimilation of the bacterial substratum by the agent still re- 

 mains open. 



THE PRODUCTION OF CARBON DIOXIDE BY THE BACTERIOPHAGE 



The question of independent metabolism of the agent of transmissible lysis has 

 been approached from other angles also. 



By using a specially constructed micro-respirometer, the writer was unable to 

 detect CO2 production by 10'- active units of bacteriophage, during a period of ninety- 

 six hours. '^ Owing to the fact that the method does not measure reliably less than 

 0.005 cc. of CO2, it is possible that the agent does respire, but that during the ninety- 



' Bronfenbrenner, J., and Muckenfuss, R.: loc. cit. 



^ Asheshov, I. N.: Compt. rend. Soc. de biol., 93, 644. 1925; Asheshov, I. N.: ibid., p. 643. 1925. 

 These "ultra-sterile" solutions were obtained by filtration of phage through collodion. 



^d'Herclle, F.: Tlic Baclcrio phage and Its Behavior, pp. 102-3. 1926. 



•• Bronfenbrenner, J., and Korb, C. : J. E.xper. Med., 42, 4S3. 1925 ; Proc. Soc. Exper. Biol. b' Med., 

 21,315. 1924. 



5 Bronfenbrenner, J.: J. Exper. Med., 45, iSSo n. 1927. ' 

 ^Wollman, E.: Com/?!, rend. Soe. dc biol., 84, 3. 1921. 

 'Wollman, E.: Ann. dcVInsi. Pasteur, 39, 7S9. 1925. 



^ Bronfenbrenner, J.: Science, 63, 51. Jan. 8, 1926; Proc. Soc. Exper. Bioi. ^ Med., 22, 81. 1924 

 Bronfenbrenner, J., and Reichcrt, P.: ibid., 24, 176. 1926. 



