346 THE BACTERIOPHAGE AND ITS BEHAVIOR 



tion only in the media with a pH of 6.8, but beyond this point, in higher 

 concentrations of H ions, the reaction did not occur or was incomplete. 

 Furthermore, he was unable to reduce this limiting concentration by 

 continuing the contacts under these conditions. When, however, the 

 passages were made at 16°C. instead of at 37°, with the filtrations 

 being made only after an incubation period of 48 hours, he obtained 

 the results in table 35 at the forty-eighth passage. 



The unadapted bacteriophage used in the above experiment had also 

 undergone 47 passages, but in a medium with a pH of 8.2. 



Furthermore, in a bouillon with a reaction of 6.0 Schuurman obtained 

 a complete bacteriophagy with the adapted bacteriophage at a tempera- 

 ture of 37°C., while the same suspension inoculated with the bacterio- 

 phage, originally of the same race but which had passed through 48 

 passages in a medium at pH 8.2, failed to show any evidences of dissolu- 

 tion. These experiments show very clearly the effects of adaptation. 



V. Wolff and Janzen*'^^ have succeeded in rendering the bacteriophage 

 tolerant toward different antiseptics, to chinosol in particular. When a 

 quantity of chinosol sufficient to provide a final concentration of 1 : 600 

 is added to a bacterial suspension inoculated with a bacteriophage and, 

 after 24 hours, a drop of this suspension is added to a fresh suspension, 

 the latter, when spread on agar, yields no plaques. After contact for a 

 week, when the bacteria are dead through the action of the antiseptic, 

 a drop inoculated into a fresh suspension yields, after incubation, a very 

 great many plaques. These experiments were performed with B. coli, 

 B. typhosus, and B. dysenteriae, as well as with the staphylococcus. 



Schuurman"^ has also succeeded in demonstrating an adaptation of 

 the bacteriophage to chinosol. 



VI. Prausnitz and Firle,^^^ after confirming the earher experiments of 

 Prausnitz on adaptation to an antibacteriophagic serum (confirmed also 

 by other authors, — Bruynoghe and Wagemans,'^" d'Herelle^*^) carried 

 out some additional experiments demonstrating adaptation to different 

 antiseptics. These are of sufficient interest to summarize here. 



Experiments with phenol. For measuring the degree of adaptation 

 they made comparative counts of the plaques derived from seeding a 

 bacterial suspension inoculated with a bacteriophage adapted to the 

 action of the antiseptic and of those obtained when a comparable sus- 

 pension was inoculated with the non-accustomed bacteriophage, both 

 specimens of the bacteriophage having been exposed to the action of 

 the same concentration of the antiseptic. The results appear in tables 

 36 and 37. 



