ANDRE LWOFF AND ANTOINETTE GUT MANN 



until the fourth minute preceding lysis, there was no liberation of bacteriophages. 



c. A diplo-bacillus was washed and brought into a drop A. Samplings made 

 at h + 35 and /i + 70 minutes are negative. At /i + 120 minutes there are four 

 bacteria. At the 140th minute, lysis of two members of a diplo-bacillus is 

 observed within a 10-second interval. The other two bacteria are transferred 

 into drops B and C. Total sampling of A: 27 bacteriophages. The bacterium in 

 drop B disappears after the 12th minute: 9 bacteriophages. After 17 minutes in 

 drop C, the remaining bacterium is transferred to D, from where, after an 

 additional 17 minutes, it is transferred into drop E. All of drops C and D are 

 sampled: no bacteriophages. In drop E, the bacterium has disappeared after the 

 third minute: 15 bacteriophages. During the 34 minutes that had preceded lysis 

 there was thus no liberation of bacteriophages by the bacterium which had 

 liberated bacteriophages in drop E. 



d. A diplo-bacillus is washed and put under observation in a microdrop. At 

 /i -|- 3 minutes there are three bacteria, at A -|- 48 minutes: 7 bacteria. At the 

 65th minute, each of the bacteria has divded in two. There are eight bacteria 

 which have remained together in one filament. At /i + 83, one of the bacteria is 

 lysed. Within 6 minutes, three other bacteria have lysed. The four bacteria 

 which have disappeared belong to the same mother bacterium . All of the fluid is 

 sampled: 579 bacteriophages. The four remaining bacteria were transferred into 

 another drop: after 22 minutes there were 10 bacteria whose fate was not 

 followed further. 



Lyses were observed in numerous other experiments, whose details are unneces- 

 sary to give here. The number of phages liberated by the lysis of a single bac- 

 terium can be inferred from the following data, where the italicized numbers 

 represent the number of bacteria lysed and the romanized numbers the number of 

 bacteriophages liberated: 2: 138, 2: 38, 2: 162, 2:27 , 1 ■.^, 1: \b, 4- 89, 4: 452, 

 .5:235, 1: 158, 2: 108, 1 : 178, 4:579, ^: 600. 4: 166; this corresponds to an 

 average of 72 phages per bacterium lysed. The lowest number was 9, the highest 

 178. It should be noted that under our observational conditions of utilizing an 

 objective ocular lens of magnification 40 and 12.5 respectively, the septum which 

 separates the two daughter bacteria is not visible at the time when it is already 

 functional. 



We often happened to observe the lysis of a bacterium of unique appearance. 

 Half of that bacterium, in fact a diplo-bacillus, disappeared under our eyes, 

 leaving for a short time a mutilated bacterium bounded by a circular surface. 

 Bacteriophage lysis thus reveals the existence of the septum although the latter 

 is not yet visible under the conditions of our observations. It is quite exceptional 

 to see single independent bacteria in the case of B. megaterium. Nevertheless, the 

 separation of the two members of a diplo-bacillus was frequently observed before 

 the lysis by the bacteriophage. We thus believe that certain of the numbers 

 which we have given really correspond to the production of phage by a single 

 bacterium. It remains possible, however, that other values which we have 

 reported for one bacterium really correspond to a diplo-bacillus. 



An important statement must be made at this time. We have seen under our 



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