296 



THE BACTERIOPHAGE AND ITS BEHAVIOR 



even of maximum virulence, which was not rendered totally avirulent 

 (or destroyed?) at a temperature in the neighborhood of 75°C., nor have 

 I found one which was rendered avirulent at temperatures below 65 °C.* 

 Hauduroy^^^ also reported experiments showing that with all races of 

 bacteriophage a true destruction takes place at the same temperature, 

 although the temperature leading to a loss of virulence may be very 

 different. He also noted that less heat is necessary to cause attenuation 

 when the virulence is low. All of his experiments were performed 

 with the same technic, hence his results are all comparable. And 

 although the conclusion which he reaches is correct, the figures which 

 he presents are certainly subject to revision. His method of testing 

 consisted in placing the bacteriophage suspension in o-pen tubes, and 

 immersing them for 3 minutes in a water-bath regulated at the desired 



temperature. Certainly under such conditions the temperature reached 

 by the liquid in the tube is not that of the water-bath. Nevertheless, 

 by this method he found that all races of the bacteriophage were de- 

 stroyed at 102°C. 



That the bacteriophage resists a temperature of 100°C. has also been 

 stated by Seilfert.^^^ jjg filtered a suspension of the bacteriophage 

 through a Berkefeld candle, and he then suspended the candle in the 

 neck of a flask containing boiling water. After 1 or 2 hours, during 

 which time the candle remained in the steam, he filtered some sterile 

 bouillon through the candle and determined whether bacteriophagy 



* We may note that Tchang Kouo Ngen and Wagemans state that this bac- 

 teriophage, which resisted temperatures up to 80°C. in one experiment, was 

 inactivated at 72°C. in a later test. This appears rather peculiar. 



