PEOPERTIES OF THE BACTERIOPHAGE 301 



determined by Mouton by the electrometric method. Scheidegger^^^ 

 reports that the corpuscles suspended in a medium with a pH of 4.5 

 remained ahve for 2 hours; and according to Davison^^^ the bacterio- 

 phage is destroyed if 1 cc. of normal NaOH is added to 4 cc. of filtrate. 



Da Costa Cruz^^"' noted that the corpuscles were flocculated in dis- 

 tilled water, but this finding does not agree with my observations pro- 

 vided the distilled water is neutral in reaction. Unquestionably 

 fiocculation takes place if the distilled water is acid, indeed, under such 

 conditions the bacteria flocculate also but as a rule, it requires a some- 

 what higher acidity to cause bacterial fiocculation. 



Reichert^^" has studied the action of acids and bases upon the bac- 

 teriophage very carefully, and according to him, the different virulences 

 manifested by a race of the bacteriophage are differently affected, some 

 resisting degrees of acidity or alkalinity which destroy others. 



This can only mean that here the intensity of the virulence, just as is 

 the case with heat, plays a determining role, within limits, upon the 

 effects observed. 



Mercuric chloride. Bacteriophage corpuscles suspended in physio- 

 logical saline containing 0.5 per cent of this salt remain alive for 3 days, 

 but they are destroyed after 4 days (d'Herelle^2i)_ gy means of com- 

 parative determinations with the spores of B. anthracis Prausnitz and 

 jrjj.jg539 jiave found that the corpuscles are slightly less resistant than 

 the spores. 



Sodium fluoride. Eliava and Pozerski^^^ j^^ve found that the bac- 

 teriophage remains alive for at least 24 hours in the presence of 2.5 per 

 cent of this salt, while under these same conditions Prausnitz^^" ob- 

 served a considerable diminution in the number of corpuscles after 3 

 days. In a 1 per cent solution the corpuscles (Shiga-bacteriophage) 

 are destroyed after 15 days (d'Herelle). 



Potassium cyanide. That a very considerable reduction in the 

 number of corpuscles occurred within 3 days in a medium containing 

 2.5 per cent of this salt has been reported by Prausnitz.^^^ In a 1 per 

 cent solution, a Staphylo-bacteriophage was markedly attenuated after 

 15 days (d'Herelle), and destroyed after 1 month. 



Sodium chloride. Marcuse^^^ states that whatever the concentration 

 of the salt, no destruction of the corpuscles takes place. If a filtrate 

 is mixed with a saturated solution of salt and if this is evaporated at a 

 low temperature the virulent bacteriophage may still be found on the 

 crystals. 



Sodium sidfate (anhydrous). Flu found that he could impregnate 



