BEHAVIOR OF BACTERIOPHAGE IN EPIDEMICS 507 



thanks to the rapidity with which the intestinal bacteriophage adapts 

 itself to bacteriophagy against pathogenic bacteria. And healthy 

 individuals, living in contact with affected people, are only spared by 

 virtue of a still more rapid adaptation occurring before morbid symp- 

 toms appear (d'Herelle^^^). 



5, FLACHERIE OF THE SILK-WORM 



A few experiments have been made on this disease, but only for the 

 purpose of determining if defense against infection in invertebrates is 

 also assured by the bacteriophage. 



In a breeding-place in Cochin-China a certain number of silk worms 

 died of a disease presenting all of the characteristics of flacherie. 

 Examination of the excreta of the sick worms, as well as of the cadavers, 

 showed the presence of a cocco-bacillus. Gram-negative, which was not 

 present in the dejections of healthy worms. The ingestion, on mulberry 

 leaves, of some of the culture of this cocco-bacillus reproduced the dis- 

 ease; eleven out of twelve worms dying in from six to eleven days after 

 the infecting feeding. 



Three filtrates were prepared from the excreta of healthy worms liv- 

 ing in the baskets where the affected worms were found. These three 

 filtrates contained a bacteriophage of moderate or high virulence 

 (++, + + + , + + +) for the cocco-bacillus. On the other hand, two 

 filtrates were prepared, the one with the intestinal contents of a sick 

 worm, the other with the intestinal contents of a worm which had died of 

 the infection. Neither contained a bacteriophage active for the cocco- 

 bacillus. 



These experiments have not been carried further, since the desired 

 end had been attained. They were adequate to show that the facts 

 observed in infectious disease in mammals were reproduced in an infec- 

 tious disease of an invertebrate. From this it seems logical to conclude 

 that the defense of the organism by the bacteriophage must constitute a 

 general fact throughout all animals (d'Herelle^^O- 



Whether it be a disease purely intestinal in nature, as bacillary dysen- 

 tery; a disease both intestinal and septicemic, as avian typhosis; a pure 

 septicemic disease, as barbone in the buffalo; or a septicemia with 

 glandular localizations, as bubonic plague; the behavior of the bacterio- 

 phage protobe during an epidemic is the same. 



During an epidemic we find, reproduced on a large scale among a 



