BACTEEIOPHAGY IN A FLUID MEDIUM 



53 



When this experiment was repeated, under certain modifications, 

 such as varying the quantity of bacteriophage filtrate within the Hmits 

 between 1 and 0.001 cc, the results were identical, despite the fact 

 that different strains of B. chjsenteriae were used. Three different 

 races of Shiga-bacteriophage, all of maximal activity, have likewise 

 given results practically identical. 



Results of the same nature as those recorded above are shown in 

 the next experiment (table 3) in which a highly active Staphylo-bac- 

 teriophage acts upon Staphylococcus aureus. Here again, incubation 

 is at 37°C. 



TABLE 3 



The suspensions containing less than 10 million staphylococci per 

 cubic centimeter were clear from the beginning of the experiment, 

 and they remained so indefinitely. After a month of standing at room 

 temperature the tubes were returned to the incubator for 48 hours. 

 No change in appearance resulted ; the aspect remained as when original- 

 ly removed from the incubator, the first two were cloudy, all of the 

 others were clear. 



The maximum number of bacteria capable of being dissolved in the 

 medium is the same, whether the total number is introduced at one 

 time at the beginning of the experiment, or whether the organisms are 

 added in several fractions. This is shown by the following experiment, 

 performed with B. dysenteriae. A salt peptone bouillon medium, ad- 

 justed to pH 7.8 is used. Incubation at 37°C. 



