BACTERIOPHAGOUS ULTRAMICROBE 127 



solved. It is interesting to note its action on bacteria resistant 

 to the action of the bacteriophage. 



Experiment XXXVII. Mix equal parts of a suspension of Shiga bacilli 

 resistant to the action of the bacteriophage, an anti-Shiga bacteriophage 

 culture, two years old, and a suspension of leucocytes. After fifteen 

 minutes, 100 leucocytes have ingested 8 bacteria. The index is thus 0.22, 

 or 90 times lees than with normal bacilli (experiment XXXIV, 2). 



Prepare a similar mixture, but with a bacteriophage culture six days old. 

 Here, 100 leucocytes have phagocytized 13 bacilli. The index is 0.38, or 

 108 times less than with normal bacilli (experiment XXXIV, 4). 



Another mixture is made, using the lysin solution, 100 leucocytes have 

 phagocytized 19 bacilli. The index is 0.53, or, 28 times less than with 

 normal bacilli (experiment XXXVI). 



From this it is clear that bacteria which resist the bacteriophage 

 also resist phagocytosis. 



The same experiment has been performed with a strain of the 

 antibarbone bacteriophage and the bacterium of barbone. The 

 results are comparable. 



Experiment XXXVIII (A) 1. Control. Mixture of equal parts of leu- 

 cocyte suspension, bouillon, and suspension of the bacterium of barbone. 

 After fifteen minutes at 38°C. there are no bacteria in 100 leucocytes. 



2. Mixture of equal parts of leucocyte suspension, the suspension of the 

 bacterium of barbone, and an anti-barbone bacteriophage culture, 8 months 

 old. 



After fifteen minutes 100 leucocytes have ingested 109 bacteria. 



3. The same mixture, except that the bacteriophage culture is diluted 

 1 : 250. 



One hundred leucocytes have phagocytized 52 bacteria. 



4. Mixture of one-third leucocyte suspension, one-third bacterial sus- 

 pension, and one-third solution of the alcohol precipitate of a recent culture 

 of the anti-barbone bacteriophage (2 mgm. of precipitate in 10 cc. of saline) . 



One hundred leucocytes have phagocytized 239 bacteria. 



(B) A mixture is made of equal parts of leucocyte suspension, culture 

 of the bacterium of barbone, and a fresh (four days old) culture of anti- 

 barbone bacteriophage. During incubation at 38°C. drops taken for 

 examination show: 



Immediately, in 100 leucocytes there are 30 bacteria. 



After two and one-half minutes, in 100 leucocytes there are 139 bacteria. 



After five minutes, in 100 leucocytes there are 201 bacteria. 



After seven and one-half minutes, in 100 leucocytes there are 271 

 bacteria. 



After ten minutes, in 100 leucocytes there are 269 bacteria. 



In the control mixture made with bouillon no bacteria were phago- 

 cytized. 



