THE BACTERIOPHAGE IN DISEASE 181 



From this time on improvement became more and more marked. 

 The activity of the bacteriophage did not disappear after con- 

 valescence had been established. 



In the first three of these cases the dysentery was mild. The 

 bacteriophage was active at the onset, the bacterium did not 

 acquire a resistance, and its growth was quickly suppressed. In 

 the last case there was a struggle and the bacillus acquired a resist- 

 ance which was finally overcome. The condition of this patient 

 was much more serious. 



5. Lans. . . . (seventy years, fig. 5). This case illustrates 

 an extremely severe dysentery due to the Shiga bacillus. The 

 patient entered the Hospital on the second day of the disease. 



In this case the struggle was prolonged, with fluctuations due 

 to the mixed cultures formed in the intestine. The condition 

 of the patient registered faithfully the changes in the struggle. 

 It may be noted particularly that the bacteriophage manifests 

 a transitory activity on the eleventh day of the disease and the 

 stools temporarily lose their bloody character. But the bacillus 

 increases its resistance and this permits it to develop, and blood 

 reappears in the stools. The disease is only definitely overcome 

 at a time when the virulence of the bacteriophage is sufficiently 

 high to dominate the resistance of the bacterium. 



Aside from the five cases cited as examples others have been 

 followed, both in France and in Indo-China. Seventeen other 

 cases differing in severity were examined daily, and twenty-nine 

 more were observed less frequently. In all of the cases the activity 

 of the bacteriophage was manifested in an identical manner: 



1. In case of recovery, the virulence of the bacteriophage com- 

 mences to manifest itself in a marked manner toward B. coli. 



2. The virulence next extends to the type strain of the Shiga 

 bacillus, that is to say, toward a strain which has been for a long 

 time under artificial cultivation and which, for this reason, has 

 been deprived of much of its resistance. 



3. It manifests itself next, more or less quickly, toward the 

 Shiga bacillus isolated from the patient himself at the onset of 

 the disease. 2 



2 Obviously it is necessary to preserve this strain without replanting. 

 The isolated colonies obtained on the original plates are planted on several 



