PROPERTIES OF THE BACTERIOPHAGE 289 



peculiar properties. We have seen that certain races cause bacteri- 

 ophagy in definitely acid media, at a pH of 5.1. Should the phenomena 

 of adsorption be the same for corpuscles capable of causing bacteri- 

 ophagy in a medium of pH 6.5 and for those capable of causing bac- 

 teriophagy at pH 5.1? It is quite within the bounds of experience to 

 doubt if the behavior of the two races will be the same, for it is very 

 probable that these differences in properties correspond to quantitative 

 differences in the electric charge. 



However this may be, the greatest cause for the lack of concordance 

 in the results reported may certainly be attributed to differences in the 

 reaction of the medium. There is the less reason to be surprised at 

 divergent results when we consider that some workers have used 

 suspensions of the bacteriophage corpuscles diluted with distilled 

 water or physiological saline neutral in reaction (often even slightly 

 acid) while others have worked with pure suspensions, that is, with 

 undiluted, alkaline, bacteriophage filtrates. 



From the beginning of my studies I have held that adsorption of the 

 corpuscles by porous candles (Chamberland) was very slight. Praus- 

 nitz^^' has to a degree confirmed this conclusion by showing that it is 

 necessary to repeat the filtration of a suspension eight times in order to 

 cause a measurable reduction in the number of corpuscles. 



It may also be recalled that I have recommended^^^ as the best technic 

 for the isolation of a bacteriophage from turbid organic fluids a pre- 

 liminary filtration through a filter paper covered with a layer of infu- 

 sorial earth. This procedure clarifies the material prior to its filtration 

 through a candle. And this technic was recommended because I had 

 demonstrated that such a preliminary filtration does not lead to a 

 diminution in the number of the corpuscles, a proof that they are not 

 adsorbed by contact with the infusorial earth. In all of my experiments 

 I have worked with the bacteriophage suspended in a fluid having an 

 alkaline reaction,^ — pH 7.6 to 8.2. 



In opposition to this conclusion Seiifert^^^ has affirmed that the 

 corpuscles are adsorbed by infusorial earth and by kaolin.* 



Gildemeister and Herzberg-^^ have observed a considerable adsorption 

 of the corpuscles by infusorial earth (Kieselguhr) . But they have added 



* This author has deduced from this that the bacteriophage is an electro-posi- 

 tive colloid, apparently forgetting that the electro-positive colloids are floc- 

 culated by OH ions, that is to say, in an alkaline medium. This is not the case 

 for the bacteriophage, since alkaline media are quite uniformly best suited for 

 work with the bacteriophage and for the process of bacteriophagy. 



