PEOPERTIES OF THE BACTERIOPHAGE 



299 



PERIOD OF 

 EXPOSURE 

 TO HEAT 



ACTIVITY OF THE BACTERIOPHAGE AFTER HEATING 



10-2 j 10-3 10-* 10-5 I 10-6 10-' 10-8 I io-» I 10-'» 



* = a dissolution of the bacterial suspension when the heated bacteriophage 

 is added. 



+ = the inoculated suspension remains turbid. 



It would appear from the number of corpuscles present, as shown by the active 

 dilution, that the bacteriophage employed by Tomaselli was of maximum viru- 

 lence. It is certain that inactivation was not complete at 70°C.; there was only 

 an appreciable attenuation of the virulence, but this was sufficient to prevent 

 a clearing of the medium. 



