VIRULENCE OF THE BACTERIOPHAGE 105 



be less active for a freshly isolated race, but after four or five 

 passages in contact with this strain a virulence is acquired equal 

 to that possessed for the first one. 



We have seen that the strains of Shiga bacilli which resist the 

 action of the bacteriophage are extremely toxic, possessed of a 

 great vitality, inagglutinable by a specific serum, and actively 

 ferment maltose. 4 



B. dysenteriae Hiss 



An anti-Hiss bacteriophage is frequently found in the nor- 

 mal intestine. A bacteriophage showing an activity for any 

 member of the colon-typhoid-dysentery group frequently shows 

 a virulence, more or less pronounced, for the Hiss bacillus. 



B. dysenteriae Hiss represents a homogeneous species from the 

 point of view of bacteriophagous activity. 



Secondary cultures reinoculated into litmus sugar media do 

 not ferment the sugars in the same way as do normal bacilli. 

 Media containing glucose, maltose, and mannite become acid 

 after ten days; those containing lactose, levulose, saccharose, 

 and also glycerine remain alkaline. After a month the lactose, 

 saccharose and levulose media remain alkaline. Secondary cul- 

 tures, and also mixed cultures, give the indol reaction but do not 

 react on either neutral red or lead acetate. The resistant bacilli 

 are inagglutinable, have a high viability, and are more virulent 

 for man. In Part II of this monograph we will consider a case 

 of B. dysenteriae Hiss septicemia in which the bacillus was re- 

 sistant to the action of the bacteriophage. 



B. dysenteriae Flexner 



The anti-Flexner bacteriophage is found in the normal intestine 

 of vertebrates as frequently as are the other strains of bacterio- 

 phage. 5 



4 Pottevin has shown that the normal Shiga bacillus definitely, although 

 somewhat weakly, ferments maltose. Resistant bacilli ferment the sugar 

 much more energetically. 



6 The presence of an active bacteriophage in pathologic conditions is 

 not considered here. This phase will be discussed in Part II of this text. 



