Aug. 19, 1922 ] SECTION OF MICROBIOLOGY. [ MBlrclX'L. 



small areas of micrococci are left— and this usually happens when the micrococcus 

 has grown well before being infected— these areas will start to grow again and 

 extend ov^er the transparent portion. . . ." 



According to this description of Twort, it is not a question of a real bac- 

 terial dissolution, but a transformation of a normal culture on agar into a 

 glassy and transparent one. This phenomenon is totally diflFerent from that 

 produced by Bacteriophagum intestinale. Indeed, under the influence of this 

 latter— no matter what bacterial species is dealt with, no matter what virulence, 

 feeble or strong, of the strain of the bacteriophage, operating exactly in the 

 same experimental conditions as Twort— in no circumstances does one observe 

 the formation of transparent material or anything presenting such an appear- 

 ance. 



Pipette over an agar tube a drop of a diluted filtrate containing a bacterio- 

 phage active towards staphylococcus; then inoculate this tube as a streak with 

 a pure culture of staphylococcus; after incubation we obtain a surface growth 

 of the organism, which macroscopically, microscopically, and biologically is 

 normal. This normal bacterial culture is strewn here and there with circular 

 clear spaces; in the interior of these spaces the agar is bare, without any 

 visible trace of any material. These bare spaces never spread over the sur- 

 rounding culture, even after months in the incubator. Furthermore, they 

 never become invaded by the surrounding bacterial culture: once formed, the 

 bare spaces remain immutable. Confusion, therefore, between the phenomenon 

 observed by Twort and the phenomenon provoked by the bacteriophage is 

 in no way possible. 



What is the nature of the principle which acts in the phenomenon of bac- 

 terial transformation observed by Twort? From a consideration of the observa- 

 tions made on this phenomenon, and in view of the fact that the lytic agent 

 and the bacteria are destroyed at the same temperature, it is probable that it 

 is derived from the bacterium itself, which is capable of splitting up into 

 fragments. Twort himself favours this view, but further experiments will be 

 necessary to settle this question. 



This conclusion, however, does not detract in any way from the interest 

 attaching to the important researches of Twort. One can already see that the 

 phenomenon observed by this author may play an important role in the 

 etiology of the so-called filtrable virus diseases, as he indeed seems to have 

 foreseen. On the other hand, the bacteriophage undoubtedly plays a part in 

 the defence of the organism in the course of infectious diseases, as I have 

 shown elsewhere. 



From a survey of the results already arrived at in the domain of scientific 

 investigation, it is easy to foresee that there exists a whole series of phenomena, 

 quite unsuspected a few years ago, whose study should play a large part in 

 the advance of scientific medicine. 



References. 



^For details see: Le Bacteriophage, son role dans I'immunite, in the collection, Mono- 

 graphs of the Pasteur Institute ( Masson, Paris ) , of which an English edition is in prepara- 

 tion (Williams and Wilkins, Baltimore, publishers). -Sur un ferment d'immunite bacteriol- 



12 



