502 THE BACTERIOPHAGE AND ITS BEHAVIOR 



In the buffaloes of a region ravaged by the disease the bacteriophage 

 preserves for a very long time its virulence for the pathogenic bacterium. 

 This, the following example shows. 



In November, 1919, a localized epizootic of barbone occurred among 

 the buffaloes of the village of Phuoc Thien (Province of Bien Hoa). 

 On a farm having twenty-one buffaloes seven died — two adult animals 

 and five aged from one to two years. The disease died out, or to speak 

 more correctly, after this, two animals recovered one after another. On 

 the 12th of the following April, that is to say, five months later, speci- 

 mens of the feces of eight of the surviving animals were collected. All 

 contained a bacteriophage active for the bacterium of barbone (six 

 were + + , two were+). 



Two specimens of the mud of a water-hole where the animals were 

 accustomed to remain immersed up to the neck during the hottest hours 

 of the day were also examined. In both a bacteriophage virulent (+ +) 

 for the bacterium of barbone was found. The destruction of the patho- 

 genic bacterium in the external medium must often be effected by the 

 bacteriophage, for it is certain that if the bacterium of barbone has 

 once been introduced into a water-hole by a sick animal the bacterio- 

 phage present there must destroy it. Furthermore, this fact shows one 

 of the modes of "contagion" of the active bacteriophage. A single 

 buffalo, in the intestine of which the bacteriophage has acquired a 

 virulence for the pathogenic bacterium, is sufficient to "contaminate" 

 all the herd which frequent the water-hole. Localized epizootics are 

 of short duration, but in spite of this we find that the pathogenic bac- 

 terium persists for several months in the external world and that the 

 ingestion of the bacteria by buffaloes is frequent, since the virulence 

 of the bacteriophage maintains itself against this bacterium. The 

 repeated ingestion of a bacterium is, as we have seen, essential for the 

 permanence of the virulence of the bacteriophage toward this bacterium. 

 The epizootic dies out, not because of an absence of pathogenic bacteria 

 but because of the presence of a virulent bacteriophage in the intestine 

 of all exposed animals. 



All of the observations are therefore comparable, whether they deal 

 with avian typhosis or with barbone in the buffalo. These epizootics of 

 very different nature were investigated intentionally, that the general 

 nature of the role of the bacteriophage in disease and in immunity might 

 be the better established. 



One may at first be quite astonished that the intestinal bacteriophage, 

 whose role can easily be conceived in infections with intestinal manifes- 



