BACTERIOLYSIS 65 



A comparable ultramicroscopic examination in the two cases 

 shows that in the last, where the inoculation was made with a 

 bacteriophage which was extremely active, at the time when lysis 

 occurs with greatest intensity, that is, between two and three 

 hours after the inoculation, the spherical forms were present in 

 greatest numbers. There were as many as two to three to a field, 

 and their rupture was readily observed. When lysis is once 

 terminated the most careful search fails to reveal such forms. 



It is here fitting to recall an observation already made which 

 should be noted by those wishing to investigate the subject. 

 When a simple diastatic action is operative it proceeds with uni- 

 form rhythm when under identical conditions. This is not the 

 case here. Up to the present time more than a hundred different 

 strains of the anti-Shiga bacteriophage have been isolated and no 

 two of them have been found to conduct themselves in an exactly 

 identical manner. The final result is always as has been indicated, 

 the phases of the phenomenon always progress in the same order, 

 but the time of the reaction will vary. With one strain of the 

 bacteriophage complete lysis is obtained in three hours, with 

 another, only after twelve hours. The phases follow each other 

 in one case four times more quickly than in the other. 



Another point which should be remembered is that all that 

 which has been said up to the present time has been in reference 

 to bacteriophagous strains which were extremely active; that is 

 to say, strains capable of producing complete lysis. 



A summary of the foregoing shows that, in so far as the micro- 

 scopic observations are concerned, there is no time when one can 

 distinguish in stained preparations, whatever the magnification, 

 microorganisms other than B. dysenteriae Shiga. Aside from the 

 bacilli one can see only formless cellular debris becoming more 

 and more abundant with the more complete destruction of the 

 bacteria, the debris later dissolving gradually. Ultramicroscopic 

 examination indicates that the ultramicroscopic bacteriophagous 

 germs multiply within the interior of the bacilli, and this observa- 

 tion is corroborated by all experiments. Such examination also 

 indicates that very probably the bacteriophagous elements are 

 represented by the very fine granules which can be observed, 

 first in the interior of the bacilli, and later in the ambient fluid. 



