308 THE BACTERIOPHAGE AND ITS BEHAVIOR 



The bacteriophage corpuscle is flocculated by acids (da Costa Cruz^^^). 

 It is adsorbed in an acid medium by kaolin and infusorial earth, but is not 

 adsorbed by these substances in an alkaline medium (Gildemeister and 

 Herzberg,^^^ Prausnitz and Firle^^^). It does not cause a reciprocal 

 flocculation in the presence of electro-negative coUoids; when admixed 

 with such substances even bacteriophagy takes place normally (d'Her- 

 elle). All of its characters indicate that the bacteriophage corpuscle is 

 the bearer of a negative electric charge (d'Herelle). It is an electro- 

 negative colloid, just as are the majority of bacterial species. 



The bacteriophage corpuscle is rapidly destroyed by ultraviolet rays 

 ( Appelmans^*) . It is not destroyed by radium emanations (Brut- 

 saert^°^). Here again it behaves hke the bacteria. 



Whatever may be the race of the bacteriophage, it becomes completely 

 avirulent (or destroyed ?) at a temperature of approximately 75°C. 

 (d'Herelle and Pozerski^'"") . The different corpuscles of a single sus- 

 pension are inactivated by exposure to very different degrees of heating. 

 With some an impairment in activity appears at a temperature as low 

 as 45°C. (De Necker*^^). The temperature of apparent inactivation is 

 related to the virulence (Hauduroy^^^). With a single race of the bac- 

 teriophage having multiple virulences, these virulences disappear in the 

 order of their intensity, the weakest first (d'Herelle). 



When exposed to cold, the temperature of liquid air, experiment 

 indicates that the resistance of young corpuscles is greater than is that 

 of older ones (d'Herelle) . 



The resistance of bacteriophage corpuscles to the action of chemical 

 agents is intermediate between that of vegetative forms and that of 

 spores of B. suhtilis (d'Herelle'^^O- As for temperature, resistance is in 

 direct proportion to the virulence, for with a single bacteriophage, the 

 weak virulences disappear first (d'Herelle). 



