INTRODUCTION 13 



contagious diseases, and all of this before anyone even attempted to 

 prove that the phenomenon itseK was real, a labor which might have 

 required a half hour's time. This is the more unusual since I had 

 published in some ten communications the facts observed and the re- 

 sults obtained. They must have considered the author as a dreamer; 

 indeed, some have since admitted that this was the case. 



BACTERIOCLYSIS : THE TWORT PHENOMENON 



In 1915, almost two years before my first communication upon the 

 subject of bacteriophagy, Twort described a phenomenon* which 

 possesses a character in common with that which I have described, 

 namely, it is reproducible in series. Aside from this common charac- 

 ter, it offers other characteristics, not merely different but which 

 preclude all possibility of identity, for the characteristics of the two 

 phenomena are mutually exclusive. But inasmuch as some authors 

 have tried, despite this, to attribute the two phenomena to a single 

 cause, quite without any experimental demonstration it is true, it 

 seems necessary to consider this subject at some length. 



First, let me present that part of Twort's paper which describes the 

 phenomenon which he observed. The transcription is literal. 



Some interesting results, however, were obtained with cultivations from 

 glycerinated calf vaccinia. Inoculated agar tubes, after 24 hours at 37°C., often 

 showed watery-looking areas, and in cultures that grew micrococci it was found 

 that some of these colonies could not be subcultured, but if kept they became 

 glassy and transparent. On examination of these glassy areas nothing but minute 

 granules, staining reddish with Giemsa, could be seen. Further experiments 

 showed that if a colony of the white micrococcus that had started to become trans- 

 parent was plated out instead of being subcultured as a streak then the micrococci 

 grew, and a pure streak culture from certain of these colonies could be obtained. 

 On the other hand, if the plate cultures (made by inoculating the condensation 

 water of a series of tubes and floating this over the surface of the medium) were 

 left, the colonies, especially in the first dilution, soon started to turn transparent, 

 and the micrococci were replaced by fine granules. This action, unlike an ordi- 

 nary degenerative process, started from the edge of the colonies, and further 

 experiments showed that when a pure culture of the white or the yellow micro- 

 coccus isolated from vaccinia is touched with a small portion of one of the glassy 

 colonies, the growth at the point touched soon starts to become transparent or 

 glassy, and this gradually spreads over the whole growth, sometimes killing out 

 all the micrococci and replacing these by fine granules. Experiments showed 



* Twort, F. W.— An Investigation on the Nature of Ultramicroscopic Viruses. 

 Lancet, 1915, ii, 1241. 



