476 WILBURT C. DAVISON 



or "lysogenic" strain. A "normal" strain is one that has never 

 been in contact with a bacteriophage. 



STOOL CULTUBE FILTRATES 



I have obtained stool culture filtrates by inoculating a loopful 

 of feces into 100 cc. of 1 per cent peptone water at pH 8. After 

 incubation at 37°C. from twelve hours to five days, these cul- 

 tures were filtered through a Handler no. G candle. The filtrates 

 were then incubated at 37°C. for forty-eight hours to prove their 

 sterility. Filtrates were made from the stools of ten infants 

 (table 1). Seven of these children suffered from bacillarj- dys- 

 entery (Flexner).^ Two of these had Bact. dysenteriae in their 

 stools at the time the filtrates were obtained. One of these two 

 patients died. Two infants suffered from acute intestinal in- 

 gestion and one was a case of Otitis Media and feeding regula- 

 tion. A bacteriophage obtained from the stool of an adult 

 convalescent tyjihoid patient' has been used as a comparison. 

 It was active against several normal strains of Flexner bacilli 

 (table 1). 



METHODS OF TESTING THE BACTERIOLYTIC ACTIVITY OF BAC- 



TERIOLYSANTS 



The bacteriolytic activity of these various filtrates was tested 

 as follows: six tubes each containing 2 cc. of sterile 1 per cent 

 peptone water (pH 8.0) were each inoculated with one drop of 

 a fluid culture of Bact. dysenteriae (Flexner). After two to 

 twelve hours' incubation at 37°C., 0.5 cc. of the filtrate to be 

 tested was added to the first tube (making a dilution of 1:5), 

 0.25 cc. to the second tube (a dilution of 1:9), and 0.1 cc. to the 

 third tube (a dilution of 1 :21). Sterile peptone water in amounts 

 of 0.5 cc, 0.25 cc. and 0.1 cc. was added to the fourth, fifth and 

 sixth tubes which served as controls. These six tubes were 



* By Flexner bacilli, I refer to the whole group of maimitol fermenting dysen- 

 tery bacilli. By Flexner V, W, X, Y or Z, I refer to the English serological divi- 

 sions of this group (Davison, 1922). 



' This bacteriophage was given me by Miss Ann Kuttner of the Department of 

 Bacteriology, Columbia University, to whom my thanks are due. 



