J. BRONFENBRENNER 539 



thermophilic bacteria was found to regenerate best at 45° to 52° C At 37° C. the 

 growth of thermophilic bacteria is retarded, and regeneration of phage is correspond- 

 ingly less rapid and less complete. Similarly, in the presence of psychrophilic bac- 

 teria, multiplying best at a temperature of from 0.05° to 4° C, the phage exhibits 

 best regeneration at this temperature range and does not regenerate at all at 37° C, 

 at which temperature the growth of psychrophilic bacteria is arrested.^ 



Thus, the regeneration of phage takes place only so long as the conditions permit 

 normal multiplication of susceptible bacteria. •> Lysis of bacteria is a secondary phe- 

 nomenon which may or may not follow the accumulation of phage, depending on con- 

 ditions of environment. 



BACTERIAL ORIGIN OF BACTERIOPHAGE 



The fact that accumulation of active agent in the medium is independent of lysis, 

 but is intimately connected with the active growth of bacteria, strengthens the view 

 expressed earlier that the phage may be some product of bacterial metabolism. 



Usually, in order to obtain active bacteriophage, one introduces into a culture 

 of bacteria some material contaminated more or less directly with intestinal contents 

 of higher animals. The nature of this material is such that the possibility of the pres- 

 ence of some living ultra-microscopic agent in it cannot be excluded. If one were able 

 to bring about the appearance and accumulation of the agent of transmissible lysis 

 in the cultures of bacteria by means which would exclude every possibility of intro- 

 duction of an extraneous living agent, the bacterial origin of phage would be definitely 

 established. 



A number of investigators claim to have accomplished this by a variety of pro- 

 cedures. However, their experiments are not free from the criticism that either the 

 material they used to induce the appearance of phage or the bacterial cultures them- 

 selves might not have been actually free from phage. From what is known about the 

 wide distribution of phage in the animal body,^ it is quite evident that phage obtained 

 by introducing bacteria into the peritoneal cavity of guinea pigs,^ or by exposing bac- 

 teria in vitro to the action of leukocytes, tissue extracts, body fluids, and ferments,'' 



' Koser, S. A.: Proc. Soc. Expcr. Biol. 0' Med., 24, 109. 1926. 



- Elder, A. L., and Tanner, F. W.: ibid., p. 645. 1927. 



3 The experiments of Wollman {Compt. rend. Soc. de biol., 84, 3. 1921) and those of Jotten {loc. 

 cit.), which suggest that regeneration of phage may take place in the absence of actively multiplying 

 bacteria, do not invalidate this conclusion. These experiments were fully discussed in an earlier part 

 of this paper. 



■'d'Herelle, F.: Compt. rend. Soc. de biol., 86, 477. 1922; ibid., 85, 767. 1921; Hoder, F., and 

 Suzuki, K.: Cenlralbl. f. Bakteriol., 98, 433. 1926; Flu, P. C: Compt. rend. Soc. de biol., 89, 970. 

 1923; Pico, C. E.: ibid., 91, 31. 1924; Wolff, L.: Ncderl. Tijdschr. v. Geneesk., 2, 1220. 1925. 



5 Otto, R., Munter, H., and Winkler, W. F.: loc. cit.; Bordet, J., and Ciuca, M.: Compt. rend. 

 Soc. de biol., 83, 1293. 1920; Bordet, J., and Ciuca, M.: ibid., p. 1296. 1920; Blair, J. E.: /. Inject. 

 Dis., 35, 401. 1924. 



^Jotten, K. W.: loc. cit.; Kuttner, A. G.: loc. cit.; Pico, C. E.: loc. cit.; Bordet, J., and Ciuca, 

 M.: loc. cit.; Borchardt, W.: Ztschr. f. Immunitdtsforsch. u. exper. Therap., Orig., 37, i. 1923; Biir- 

 gers, T. J., and Bachmann, W.: ibid., loi, 350. 1924; Pico, C. E.: op. cit., 89, 753. 1923; Lisbonne, 

 M., Boulet, L., and Carrere, L.: ibid., 86, 340. 1922; ManoHu, E.: ibid., 92, 724. 1925; Gratia, A.: 

 ibid., 85, 25. 1921; Putter, E., and Vallen, S.: Klin. Wchnschr., 2, 339. 1923. 



