INTRODUCTION 

 I. Historical 



THE PHENOMENON OF BACTERIOPHAGY 



Before considering the historical development of our knowledge 

 concerning the phenomenon of bacteriophagy, let us consider the cir- 

 cumstances which offered a veiled suggestion that such a phenomenon 

 existed, although none of the facts pertaining to the reaction were at 

 that time known. Let us consider the initial observation which served 

 as the starting point for the study of the phenomenon of bacteriophagy. 



During the course of the investigation of a disease, bacterial in 

 origin, affecting locusts, first noted in Mexico in 1909 where whole 

 swarms of the insects succumbed to the infection* several new facts 

 were observed. The disease, as it occurred naturally was primarily a 

 septicemic condition, accompanied by intestinal disturbances, as re- 

 vealed by the profuse diarrhea seen in the infected insects. The 

 pathogenic microorganism, Coccobacillus acridiorum, was present in the 

 intestinal fluids in great abundance. 



Inasmuch as these locusts constitute an insect pest, causing enor- 

 mous destruction of crops in many tropical regions, and indeed in some 

 sub-tropical zones, it seemed that it might be possible and distinctly 

 advantageous to artificially implant this natural epizootic among the 

 colonies made up of larval forms and thus destroy the harmful insects 

 in large numbers. To this end, the virulence of the coccobacillus was 

 enhanced by successive passages through locusts in the laboratory. 

 Large quantities of a fluid culture medium were inoculated with the 

 bacterium and this material, after incubation, was distributed from 

 place to place among the masses of insects, still in the larval state. 

 Under such conditions the disease developed rapidly. f 



* d'Herelle— Sur une epizootie de nature bacterienne sevissant sur les Sau- 

 terelles en Mexique. Compt. rend. Acad, sci., 1911, 152, 1413. 



t Consult on this subject: 



d'Herelle— Le Coccobacille des Sauterelles. Ann. Inst. Pasteur, 1914, 28, 

 280; 387. 



Beguet, M. — Deuxieme campagne contre les sauterelles Stauronotus maroc- 

 canus Thun. en Alg^rie au moyen du "Coccobacillus acridiorum" d'Herelle. Ana, 

 Inst. Pasteur, 1915, 29, 520. 



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