BACTERIAL AUTOLYSIS 



561 



eight days, but remained stationarj' after this period. Its 

 increase was not proportional to the amino nitrogen increase. 



Bacterium coli 



In the first study 14 experiments were conducted with six 

 different strains of Bad. coli. No decrease in the intensity of 

 the biuret reaction could be observed except in three instances 

 in which only a slight change was apparent. In four of the 

 tests only a small increase in the Sorensen figures was shown. 



The biuret tests in this series were less delicate than those 

 which followed. In the preparation of standards 0.25 per cent 



TABLE 1 

 Shoimng amino nitrogen changes during incubation of suspensions of Bad. coli. 



solutions of Witte's peptone were used, these giving a series of 

 standards with 0.25 mgm. intervals between successive tubes. 

 Each interval represents 0.025 on the ordinate of the biuret 

 graph. Closer readings were not attempted. 



Table 1 gives the results of Van Slyke determinations of amino 

 nitrogen on 9 different suspensions. While they are not de- 

 cisive, they do indicate that an increase in amino nitrogen 

 may take place. In the three instances where no increase was 

 shown the bacterial suspensions were prepared from cultures 

 only twenty-four hours old or less, and the appropriate enzjTues 

 may not have had time to develop. The amino nitrogen content 



