172 



A second experiment with T (Sm) instead of T (Wi) offered an 

 analogous result. 



After a week the number of bacteriophagus germs with the resist- 

 ant strain was about the same as the number found after 24 hours ; 

 with the non resistant strain it had greatly increased. 



We have regularly found tlie slight increase (in comparison with 

 the number after 7^ ''Our and after 7* — ^ hour) with the resistant 

 strain; the explanation seems to us as follows: the resistant strain 

 also has some weaker descendants which can be dissolved by the 

 bacteriophagus; hence an increase of the bacteriophagus, which is 

 now being caught by the stronger brothers. 



We can easily succeed in destroying the bacteriophagus by cul- 

 turing three of four times on broth with new bacilli the mixture 

 of bacteriophagus-resistant strains in fresh broth. 



4th 

 5th 



disappeared? 

 disappeared 



