BACTERIOLYSIS 61 



body bursts. This liberates the colony of ultramicrobes which 

 have been formed in the bacterial protoplasm. A confirmation 

 of this fact is obtained by examination of the phenomenon under 

 the ultramicroscope, and by a study of the temporarily inhibitory 

 action of an anti-bacteriophagous serum. 



It has been shown that the successive increases in number are 

 separated by intervals of approximately seventy-five to ninety 

 minutes. On the other hand, a complementary experiment, 

 conducted in the same fashion, but centrifuging the suspension 

 at ten minute intervals during the first half hour, has shown that 

 very few of the bacteriophagous germs are fixed during the first 

 ten minutes, although they are almost all fixed after twenty 

 minutes. The union, therefore, requires about a quarter of an 

 hour. 



Given the rapidity of multiplication of the ultramicrobe, and 

 the time consumed in effecting each successive increment, it can 

 readily be calculated that a single bacteriophage within a bacterium 

 produces a colony varying in number from fifteen to twenty-five 

 individuals; and it does this within the space of an hour or an 

 hour and a quarter. 



BACTERIOLYSIS UNDER THE MICROSCOPE 



The anti-Shiga bacteriophage is always taken as an example 

 in considering the action on dysentery bacilli. 



It has been seen that when the inoculation with the bacterio- 

 phage is massive all the bacteria are attacked at the beginning, 

 in other words, their multiplication is abruptly arrested. After 

 two to three hours the medium commences to clear little by little 

 and becomes completely limpid a short time later. If, on the 

 contrary, the inoculation is minimal, the few ultramicrobes inocu- 

 lated only affect an equal number of bacteria. The great majority 

 remain unaffected and multiply as they would in a normal medium. 

 But the ultramicrobes likewise multiply, following a progression 

 more rapid than that pursued by the bacteria, so that within a 

 few hours their number becomes equal to, or greater than, that of 

 the bacteria. This is the time when macroscopic lysis commences. 



1. Let us consider the first case, that of the massive inocula- 

 tion. If we take from time to time a drop of the suspension 



