BEHAVIOR OF BACTERIOPHAGE IN DISEASE 477 



cultures taken during the first week of typhoid fever. All four were 

 positive for B. typhosus, but in none of them could I detect a bacterio- 

 phage. In making the tests I combined the filtrates of the blood with 6 

 different laboratory strains of B. typhosus and with the strains isolated 

 from the stools of each of the patients. In each instance 12 consecutive 

 passages were made. Examinations made of the intestinal bacterio- 

 phage in these four cases showed that in no instance did it possess any 

 virulence for B. typhosus, either for the stock culture strains or for the 

 strains isolated from the blood or from the stools. 



Of 5 cases in which positive blood cultures were secured during the 

 second week of the disease, four contained no detectable bacteriophage, 

 but from the fifth case, on the contrary, I isolated a bacteriophage 

 virulent for the strain of B. typhosus procured from the stools four days 

 previously. In the first four cases I was unable to show that the in- 

 testinal bacteriophage had any virulence for B. typhosus of any strain 

 whatever. In the fifth, the race of bacteriophage present in the intestine 

 had a moderate virulence for the strain isolated 4 days previously from 

 the stools. 



It seems, then, that the presence of the bacteriophage in the blood 

 may be correlative to its acquisition of virulence in the intestine. 



In another communication on the same subject^"® Hauduroy presents 

 the following observations, which throw some fight on the fact, ap- 

 parently paradoxical, of the possible presence of the bacteriophage in a 

 positive blood culture. In the course of his investigations he secured, 

 quite by chance, blood cultures in three cases at a time which, although 

 the temperature was then between 39 and 40°C., happened to be almost 

 immediately before defervescence began. In these three cases the fall 

 in temperature was abrupt and the patients recovered without incident. 

 The blood cultures were placed in the incubator and were examined 

 daily for several days. After 24 to 48 hours, he found that all three 

 contained organisms, — ^motile, Gram-negative, morphologically to all 

 appearances B. typhosus. Two or three days later these bacilli had dis- 

 appeared. It was impossible for him to find a single bacterium,* and 

 search for the bacteriophage yielded a race extremely active for B. 

 typhosus. As Hauduroy remarks, the blood cultures in these three 

 cases were temporarily positive. 



In brief, we may say that in a blood culture containing^ both B. 

 typhosus and the bacteriophage, the result of the culture depends upon 



* The observation of Eliava, mentioned in the Introduction to this text, rela- 

 tive^to the disappearance of the cholera vibrios from cultures made of the water 

 of the Koura river, may be recalled in this connection. 



