J. BRONFENBRENNER 555 



cause in these experiments phages which were used were known to be highly potent, 

 having been previously tested against the infecting organisms /;/- vitro. Moreover, the 

 administration of phage in these experiments was not limited to the digestive tract, 

 but in many experiments was supplemented by subcutaneous, intraperitoneal, or 

 intravenous administration. The inquiry into the causes of these failures has shown 

 that they could not be ascribed to the survival of resistants' alone, as postulated 

 by D'Herelle, but undoubtedly are due also to the fact that under the conditions 

 existing in vivo the susceptible bacteria are not subject to lysis as freely as they are 

 in vitro. It was found that, in spite of the presence of numerous susceptible bacteria, 

 bacteriophage does not accumulate in vivo at a rate comparable to that observed in 

 vitro.'' This is undoubtedly due in part to the fact that in vivo bacteria multiply 

 more slowly (and thus less phage is produced) and partly to the fact that a consider- 

 able portion of the phage which is produced (or introduced for therapeutic purposes) 

 is quickly immobilized by adsorption on colloids of tissues and of body fluids.'' More- 

 over, bacteriophage is continuously and rapidly eliminated from the circulation 

 through the bile and urine,'' so that when it is introduced experimentally into animals 

 it may be completely eliminated, according to D'Herelle, in from twenty-four to 

 forty-eight hours, unless susceptible bacteria are present and thus some regenera- 

 tion of phage can take place.^ 



In view of these findings, limited activity of phage in vivo should not be surprising. 

 The experimental evidence presented in the early part of this paper suggested that 

 in vitro as well the rate of regeneration of phage depends on the rate of multiplica- 

 tion of susceptible bacteria. It was shown also that the presence of some colloids 

 may interfere with the progress of diffusion of phage through adsorption (as in the 

 case of excess of agar) and thus cause lysis in spots only (plaques) instead of diffuse, 

 complete lysis as it occurs in broth where the action of phage on bacteria is unopposed. 

 Furthermore, it was shown that in the presence of colloids (as gelatin, for instance) 

 the phage and the susceptible bacteria may be present, and the phage may even show 

 increase in concentration without causing the complete dissolution of bacteria. 



Similar difficulties present themselves in the attempt to utilize bacteriophage for 



' At least in some instances, as in the case of experimental mouse typhoid caused by B. pestis 

 caviae, the resistants have been found to be devoid of virulence (Bronfenbrenner, J., Muckenfuss, R., 

 and Korb, C: loc. cit.). 



2 Doerr, R., and Gruninger, W.: loc. cit.; Meissner, H., and Baars, G.: Centralbl.f. Bakteriol., 

 Beiheft. 93, 131. 1924; Wertemann, A.: Das Verhallen der iibertragbaren Lysine in der Zirculation 

 von Kalt und Warmblutern. (Dissertation.) 1922. 



3Zdansky, E.: loc. cit.; Seiffert, W.: Senchenbekampfung, 2, 234. 1925; Clark, P. F. and A. S., 

 /oc.«7.; Meissner, H., and Baars, G.: loc. cit.; Zdansky, E.: Wien. Arch.f. inn. Med., 11, 533. 1925. 



1 Doerr, R., and Gruninger, W.: loc. cit.; Wertemann, A.: loc. cit.; Appelmans, R.: Compt. rend. 

 Soc. de biol., 85, 722. 1921; Suzuki, T.: /. Orient. Med., 2, 125. 1924. 



sd'Herelle, F.: The Bacteriophage and Its Behaiior, p. 538. 1926. The elimination of bacterio- 

 phage cannot be counteracted by increasing the therapeutic dose because of the toxicity of many 

 phages (Seiffert, W.: Ztschr.f. Immtinitatsjorsch. u. exper. Therap., Grig., 38, 350. 1923; Meissner, H., 

 and Baars, G.: loc. cit.; Hauduroy, P.: Ann. de med., 16, s4o- 1924)- Repeated administration 

 of moderate amounts of phage over a long period is inadvisable because of the development of 

 antiphage which abolishes all phage action (Hauduroy, P.: loc. cit.; Compt. rend. Soc. de'hc^.^ 

 290. 1924; Fabry, P.: ibid., 94, 774. 1926). 





