STREPTOCOCCUS HEMOLYTICUS 



171 



hours incubation to insure sterility each flask was inoculated 

 with 1.25 cc. of an active twenty-two-hour culfure. Determi- 

 nations of Ph and "reaction" were made after an incubation 

 period of four days. The "reaction" was determined by titrat- 

 ing 5 cc. of culture with n/50 NaOH, using neutral red as an 

 indicator and calculating the number of cubic centimeters of n/1 

 NaOH needed to neutralize the acid in 100 cc. of culture. Table 

 3 contains the results of the experiment. 



TABLE 3 

 Experiment III 



* Cubic centimeters of n/1 NaOH required to neutralize 100 cc. of culture. 



As will be seen by referring to table 3 the final Ph characteris- 

 tic of the streptococcus is not reached in the media containing 

 0.3 per cent and 0.5 per cent glucose plus 1 per cent phosphate 

 (numbers 4 and 8 in table). These concentrations of glucose 

 are apparently not sufficiently great to allow the formation of 

 enough acid to bring the culture to the characteristic level, 

 whereas in the case of the 1 per cent glucose plus 1 per cent 

 phosphate a characteristic final Ph is reached. Correlated with 

 these facts are the differences in titratable acid as shown in the 

 last column of the above table. It is an interesting fact that 

 virtually the same final Ph is shown in the greater number of the 



