The Bacteriophage: Its Phenomenon, Nature, And Behavior
In introducing the phenomenon of the bacteriophage, we shall first consider the circumstances which offered a veiled suggestion that such a phenomenon existed. The first instance in which this action was observed was in the course of the investigation of a bacterial disease affecting locusts. The disease was first noted in Mexico in 1909 where whole swarms of the insects succumbed to the infection (1). The disease, as it occurred naturally was primarily a septicemic condition, accompanied by intestinal disturbances. The pathogenic microorganism, Coccobacillus acridiorum, was present in the intestinal fluids in great abundance. Inasmuch as these locusts constitute an insect pest, 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. The preparation of cultures for the mass infection of the colonies of insects involved the isolation of the virulent coccobacillus from the intestinal contents of locusts with an experimental laboratory infection. On several occasions the culture tubes used for isolation, or for transplanting the cultures, 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. This absence of growth is now known to be due to the action of the bacteriophage.