480 WILBURT C. DAVISON 



The bacteriolytic activity of these filtrates was also tested in 

 several instances by dropping a small portion of the filtrate on 

 the surface of an agar plate which had been heavily inoculated 

 five to twenty-four hours previously with Flexner bacilli. These 

 plates were than incubated for twenty-four hours and the presence 

 or absence of macroscopic lysis in the area bathed by the filtrate 

 was noted. The presence of "moth eaten" colonies in subcul- 

 tures of these areas confirmed the occurrence of Ij'^sis. 



ORGANISMS ATTACKED BY STOOL BACTERIOLYSANTS 



Five stock laboratory Flexner strains, twenty freshly isolated 

 Flexner strains, one stock laboratory Shiga strain and one stock 

 laboratory typhoid strain were all lysed by one or more of sixty- 

 eight bacteriolysants (either original stool filtrates or their sub- 

 sequent generations) obtained from eleven patients (table 1). 



VARIATIONS IN THE BACTERIOLYTIC ACTIVITY OF STOOL BAC- 

 TERIOLYSANTS 



All of the sixty-eight bacteriolysants. some of which were tested 

 against as many as eleven among this total of twenty-seven 

 strains were active against one or more strains. Some filtrates 

 attacked several strains, others only one. Among the two 

 hundred and twenty-five lysis tests performed with these sixty- 

 eight filtrates and twenty-seven strains, twenty-five tests were 

 negative. 



Among fifty filtrates which were tested against two to eleven 

 different strains, fifteen (or 30 per cent) had the same titre of 

 lysis against all of the organisms against which they were tested, 

 i.e., filtrate no. 31 (4) when dUuted 1:21 lysed all seven of the 

 strains of the Flexner bacillus against which it was tested. Thirt}-- 

 five filtrates (or 70 per cent) produced lysis in different dilu- 

 tions, i.e., filtrate no. 33 (1) lysed six strains at a dilution of 1:21 

 and one strain at 1:5. The bacteriolytic titre of eight filtrates 

 was tested against four dysentery cultures obtained bj^ fishing 

 four separate colonies from the same plate of a stool culture. 

 Six of these filtrates lysed all four cultures at a dilution of 1 :21 

 while the seventh filtrate lysed one culture at 1:21, two cultures 



