2 THE BACTERIOPHAGE AND ITS BEHAVIOR 



As has been said, the preparation of cultures for the mass infection 

 of the colonies of insects involved the isolation of the virulent cocco- 

 bacillus from the intestinal contents of locusts with an experimental 

 laboratory infection. And in this procedure certain observations were 

 made which now offer the point of greatest interest. On several occa- 

 sions the culture tubes used for isolation, or for transplanting the cul- 

 tures, yielded colonies which were of indented irregular contour, or, 

 in the midst of a group of confluent colonies there were at times areas 

 entirely free of growth. These cultural irregularities were sufficiently _ 

 pronounced to arouse my curiosity, and to explain them, and the 

 phenomenon leading to their formation, an hypothesis was advanced, 

 one which proved to be entirely false. Indeed, it must be added that 

 for a very long time this hypothesis led me to perform many useless 

 experiments. 



In accord with this hypothesis it seemed that the coccobacillus could 

 only be an "associated" organism, the true pathogenic agent neces- 

 sarily being an ultramicroscopic organism, which, occasionally reaching 

 the agar, inhibited the growth of the associated bacterium. This 

 hypothesis appeared the more natural in view of the admirable work 

 of de Schweinitz and Dorset upon hog cholera. But, after having 

 demonstrated that the filtrate by itseK contained nothing virulent for 

 the locust the hypothesis was modified in accordance with the concept 

 that the disease required that two agents, visible and invisible, be 

 simultaneously present. 



Throughout a long series of investigations attempts were made to 

 determine if this hypothesis could be reconciled with the observed facts 



Beguet, M. — Campagne d'exp^rimentation de la methode biologique centre Ic 

 Schistocerca peregrina en Algerie de Decembre 1914 a Juillet 1915, et en particular 

 dans la region de Barika (Departement de Constatine). Ann. Inst. Pasteur, 

 1916, SO, 225. 



Velu, H., and Bouin, A. — Essai de destruction du Schistocerca peregrina au 

 Maroc par le "Coccobacillus acridiorum" du d'Herelle. Ann. Inst. Pasteur, 

 1916, 30, 389. 



Velu, H. — Deuxieme campagne d'experimentation de la methode d'Herelle 

 au Maroc contre Schistocerca peregrina Olivier. Ann. Inst. Pasteur, 1917, 81, 

 277. 



Revista del Ministerio de Industrias del Uruguay, 1918. 



Revista del Ministerio de Obras publicos de Venezuela, Suppl., 1913. 



Cheyssial, A. — Experimentation de la methode de d'Herelle en Guin^e fran- 

 Qaise pour la destruction des acridiens. Bull. Soc. path, exot., Par., 1922, 15, 

 762. 



