ANDRE LWOFF AND ANTOINETTE GUTMANN 



high to correspond to the lysis of only two bacteria. It is possible that, in this 

 experiment, the mixing before the first sampling was insufficient. 



C. A filament of three bacteria is washed and transferred into peptone water. 

 The history of these three bacteria, a, h, and c, which remained in a single 

 filament, is indicated in the table below. One notices that bacterium a divided 

 twice, and that the four bacteria which issued from its division lysed between 

 the 88th and the 114th minute. 



A sampling of 1 X 10^ /x^ undertaken at the 114th minute did not reveal 

 bacteriophages. A sampling of 1.4 X 10^ at the 142nd minute revealed the 

 presence of 71 bacteriophages. Sampling the total fluid at the 155th minute 

 (116.3 X 10* n^) revealed 400 bacteriophages. If one takes into account the ratio 

 of these volumes, one concludes that the total number of bacteriophages must 

 have been approximately 900 at the instant of the 2nd sampling. It is to be noted 

 that the first sampling at the 114th minute was negative while at the 142nd 

 minute there was the appearance of numerous bacteriophages without there 

 having been any lysis of other bacteria. It is possible that also here, as in the 

 preceding experiment, the mixing of the culture medium was insufficient. It is 

 also possible that after lysis the bacteriophages remained engulfed in the viscous 

 cellular debris for some minutes and thus escaped the action of mixing currents. 



Another experiment should allow us to recognize the character of the lysis by 

 the bacteriophage. A diplo-bacillus is washed and inoculated in one drop of 

 proteose peptone. At the 26th minute, there are two diplo-bacilli, of which one 

 is removed. At the 72nd minute, two other diplo-bacilli are removed. There a 

 filament containing 4 bacteria remains in the drop. A sampling of 6.5 X 10^ ju^ 

 made at this moment is negative; at the 143rd minute there is a filament of 8 and 

 a filament of 10 bacteria. One sees one of the bacteria — perhaps one diplo- 

 bacillus? — • disappear in about 1 second without leaving any trace. One samples 



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