INVESTIGATIONS ON A LYSOGENIC BACILLUS MEGATERIUM 



After the 123rd minute one removes 28 X 10'' /x^ of medium, representing 

 approximately 90% of the volume of the drop: 480 bacteriophages. The 

 bacteria remained united in the long filament. No lysis had been observed. 

 No ghost was visible. We thus concluded that it might be possible that the 

 production of bacteriophages proceeds in the absence of bacterial lysis. At this 

 time we knew only one type of lysis: the slow lysis in which a well recognizable 

 ghost persists and we thought that the absence of such a ghost implies the absence 

 of lysis. Since then, we have recognized another rapid type of lysis, in the course 

 of which the bacteria disappear in less than one second without leaving a recog- 

 nizable residue. This is the type of lysis which liberates bacteriophages. Several 

 terminal bacteria could well have lysed in the course of this experiment, and this 

 lysis could have gone unnoticed. This experiment can thus not be retained to 

 support the thesis of a liberation of bacteriophage without bacterial lysis. 



B. A diplo-bacillus is washed and placed in peptone water. One notices, 

 according to the table below, that one bacteria disappeared between the 50th 

 and the 55th minute, two disappeared between the 61st and the 62nd minute: 



Samples were taken from the microdrops after 14, 43, and 55 minutes respec- 

 tively 2.5 X 10^ 4 X 10^ and 2.4 X 10^^: no bacteriophages. At the 63rd 

 minute, one samples 2.4 X 10^ /x^: 18 bacteriophages. At the 83rd minute, 

 3.2X10^^:17 bacteriophages. At the 115th minute 5.15X10^^:68 

 bacteriophages. The residual volume was 92 X 10^ /x^- The initial volume was 

 thus 149 X 10^ M^- One can thus calculate that the number of bacteriophages at 

 the time of the three samplings was 11 30, 725, and 190. It is to be noted that the 

 sampling made at the 55th minute, after the disappearance of one bacterium, did 

 not reveal any bacteriophages. In this experiment the bacteria were motile. It is 

 possible that the first lysis was a slow lysis which did not produce bacteriophages 

 and in which the bacterial ghost remained unnoticed. One also notices that the 

 calculated number of bacteriophages was 1,130, a number which seems to us too 



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