538 THE BACTERIOPHAGE 



depends entirely on its being set free through the dissolution of bacteria, there can 

 be no accumulation of phage without lysis, and lysis must be accompanied by the 

 increase in the concentration of the active agent in the medium. 



However, a number of observers have brought forward evidence showing that such 

 is not the case. Careful experiments, in which the rate of regeneration of the phage 

 was followed at the same time as bacterial counts were made, have shown that in- 

 crease in the phage concentration is entirely independent of the lysis of susceptible 

 bacteria. It was found that in the presence of undiluted phage the susceptible bac- 

 teria undergo complete lysis without increasing the concentration of the phage in the 

 medium.' On the other hand, if the initial concentration of phage in the medium is 

 low, one can detect the production of new phage long before any lysis of bacteria 

 sets in.^ Moreover, under special experimental conditions visible lysis can be entirely 

 prevented in spite of the normal regeneration of the phage to its maximum.^ 



According to these findings, far from being the product of lysis, the active agent 

 is regenerated during the stage of active multiplication of susceptible bacteria pre- 

 ceding the lysis. If the rate of multiplication of bacteria is low, either due to the age 

 of the culture or as a result of experimental conditions, the rate of accumulation of 

 the active agent may be not only materially reduced,^ but its concentration in the 

 solution may actually diminish through adsorption on bacteria.^ Such is the case, for 

 instance, when bacterial cultures containing the phage are incubated at 43°-45° C. 

 instead of 37° as ordinarily.*^ 



That the failure in production of new phage at this temperature is due to changes 

 in bacteria, and not in the agent itself, can be inferred from the fact that phage is 

 comparatively resistant to heat, and shows no deterioration until the temperature 

 is raised at least above 60° C. Moreover, it has been found that bacteriophage regen- 

 erates normally even at higher temperatures than 45° C. if susceptible bacteria can 

 multiply at these temperatures. While ordinarily the optimum temperature for the 

 regeneration of phage is about 37° C. (with extreme limits beyond which no traces of 

 regeneration or lysis can be observed, at 8° and 48° C, respectively'), the phage for 



' Matsumoto, T.: loc. cit.; Bail, O., and Matsumoto,T.: Med. Klin., 19, 1579. 1923; Meuli, H.: 

 Zlschr. f. Hyg. u. Infektionskrankh., 99, 46. 1923. 



^Doerr, R., and Gruninger, W.: loc. cit.; Saldanha, A.: Arch, do Inst. bad. Carnara Pcstana, 5, 

 266. 1924. A similar observation was made also by Muckenfuss in the laboratory of the writer. 



3 da Costa Cruz, J.: loc. cit.; Brutsaert, P.: loc. cit.; Matsumoto, T.: loc. cit.; Saldanha, .\.: loc. 

 cit.; Doerr, R.j and Berger, W.: Zlschr. J. Hyg. u. Infektionskrankh., 97, 422. 1923; Otto, R., and 

 Munter, H.: ibid., 100, 402. 1923; da Costa Cruz, J.: Mem. do Inst. Oswaldo Cruz, 16, 104. 1922; 

 Zdansky, E.: Scuchenbckdm pfung, 2, 150. 1925. 



-t Doerr, R., and Gruninger, W.: Zoc. cit.; Zdansky, E.: loc. cit.; d'Herelle, F.: Com pi. rend. Acad, 

 sc, 167, 970. 1918; Otto, R., and Winkler, W. F.: Deutsche med. Wchnschr., 48, 383. 1922; Doerr, 

 R.: Schiceiz. med. Wchnschr., 53, 1009. 1923; Scheidegger, E.: Ztschr. f. Ilyg. u. Infektionskrankh., 

 99, 403. May 15, 1923; Bruynoghe, R., and Mund, W.: Compt. renu. Soc. de biol., 92, 464. 1925. 



5 Otto, R., and Winkler, W. F.: loc. cit.; Doerr, R.: loc. cit. 



* Doerr, R.: loc. cit.; Kuttner, A. G.: Proc. Soc. Exper. Biol. &' Med., 18, 158. 1921; d'Herelle, 

 F.: The Bacteriophage and Its Behavior, p. 75. 1926. According to D'Herelle, this phenomenon is 

 not general and can be reproduced with certain strains of phage only (d'Herelle, F.: The Bacterio- 

 phage and Its Behavior, p. 61. 1926). 



7 d'Herelle, F. : The Bacteriophage and Its Behavior, p. 75. 1926. 



