2i8 Samuel C. Prescott 



tural features as well as morphologically. They likewise exhibit the 

 same staining reactions, colorizing readily with the usual stains and 

 also by Gram's method. 



COMPARISON OF ACID PRODUCTION. 



The comparison of acid-producing power of the organisms was 

 made as a further test of their identity. For this purpose we made use 

 of I per cent lactose broth and i per cent maltose broth, both made with 

 reaction o.o at the beginning of the experiment. 



. . . N 



The acidity was determined by titration against — NaOH, using 



phenolphthalein as an indicator. 



The acid in the lactose broth cultures was measured after 96 hours, 

 and in the maltose broth cultures after 48 hours. 



Five cultures of streptococci from grains required an average of 



N 

 2.48 c.c. of — NaOH to neutralize =: c.c. of the cultures in lactose 

 20 -^ 



broth. 



Five cultures from feces required an average of 2.51 c.c. of 



N 



— NaOH cultures in lactose broth. 

 20 



Six cultures of streptococci from grains required an average of 



N 

 1 . 78 c.c. of — NaOH to neutralize k c.c. of cultures in maltose broth. 



Five cultures from feces required an average of 1.83 c.c. of 



N 



— NaOH cultures in maltose broth. 

 20 



These results show that there is no essential difference in the acid- 

 producing power of the organisms. Taking the averages — 2 . 48, 2 . 5 1 , 

 1.78, and 1.83, respectively — it is obvious that the differences are 

 quite within the experimental error in a determination by this method. 



Judged by biochemical or microscopical characters and fer- 

 menting powers, it is impossible to distinguish between the organisms 

 from the two sources, and we must regard the species Strept. pyogenes, 

 as well as B. coli, as having a very wide distribution in nature, and 

 not merely associated with animal organisms. Its occurrence appears 

 to us to be in some way correlated with the presence of carbohy- 

 drate food, and it is evident that it can obtain this either in the intes- 



