482 WILBURT C. DAVISON 



Among thirteen filtrates heated immediately after filtration 

 to 60 to 67°C. for forty-five to sixty minutes, the titre of lysis 

 was reduced in five, apparently increased in two and unchanged 

 in six. The changes were however so shght as to be within the 

 range of experimental error, so that it is probable that the bac- 

 teriolytic power of a filrate is unaffected by these temperatures. 



The degree of lysis is also dependent upon the concentration 

 of the bacteriolytic filtrate, lysis frequently occurring at a dilu- 

 tion of 1:5 and being absent at 1:9, or 1:21. 



LOSS OF BACTERIOLYTIC ACTIVITY WHEN A BACTERIOLYSANT IS 



SUCCESSIVELY SUBCULTURED IN STERILE PEPTONE WATER 



OR IN A CULTURE KILLED BY HEAT 



A bacteriolysant was added to a flask of sterile peptone water 

 incubated twenty-four hours at 37°C. and then filtered. A 

 portion of this filtrate was then added to another flask of sterile 

 peptone water, incubated twentj^-four hours at 37°C. and then fil- 

 tered. A portion of this filtrate was then added to another flask of 

 sterile peptone water, incubated twenty-four hours and then 

 filtered. This was repeated for six such "passages." The 

 bacteriolytic activity which was marked in the original bac- 

 teriolysant became progressively weaker and disappeared after 

 the fifth passage, i.e., when the original bacteriolysant was di- 

 luted 1 : 7776. Although undemonstrable in the fourth "passage" 

 when the original bacteriolysant was diluted 1:1296, yet sub- 

 cultures of the dysentery bacilli which had been incubated with 

 this filtrate contained a few "sensitive" colonies so that a slight 

 amount of lytic activity was probably present at that dilution 

 (table 4). 



The effect of filtration on the bacteriolytic activity of these 

 preparations was also studied, i.e., after the bacteriolysant had 

 been incubated with sterile peptone water, the bacteriolytic 

 activity of a portion of it was tested. The remainder was then 

 filtered and the bacteriolytic activity of this filtrate tested. The 

 titre of lysis of the unfiltered and the filtered portions was the 

 same. 



