230 LAURENCE F. FOSTER 



ammonia formation, whereas the laboratory culture showed a 

 decided increase in amino acid output coupled with a slight 

 decrease in ammonia excretion. Whether or not this deviation 

 represents a permanently altered aspect of metabolism on the 

 part of the laboratory strain must for the present remain un- 

 decided. It may be that through continued cultivation upon 

 artificial media the organism has gained the ability to inaugurate 

 proteolysis earlier. Such a conclusion would be opposed to 

 the finding of Rosenthal and Patai (1914) that a virulent strepto- 

 cocci were less strongly proteolytic than cultures of the same 

 strain the virulence of which had been increased by animal 

 passage. In the present experiment the curves of nitrogen 

 metabolism (figs. 6 and 7) show the same general features from 

 the third hour to the end of the period of observation. No 

 differences in the growth, acid formation, or glucose utilization 

 were evident in the two cultures throughout the entire period 

 of the experiment. 



SUMMARY AND CONCLUSIONS 



1. Lactic acid appears to be the principal acid formed by 

 Streptococcus hemolyticus in its fermentation of glucose broth. 

 A smaller proportion of volatile acids is formed. This fraction 

 is made up chiefly of acetic, with perhaps a trace of formic acid. 



2. A quantitative study of the ammonia excretion of the 

 streptococcus indicates that a "protein sparing" action occurs 

 in media containing available sugar to meet the energy require- 

 ment of the developing cells. 



3. The maximum periods of glucose utilization and acid 

 formation in glucose and in glucose-serum broth are correlated 

 with growth at a maximum rate, though a considerable lowering of 

 Ph occurs during the period when growth proceeds at a diminish- 

 ing rate. 



4. The greatest increase in output of ammonia is correlated 

 in a general way with the maximum periods of growth, glucose 

 utilization, and acid formation. Associated with this increased 

 output of ammonia a corresponding decrease in amino acids is 

 evident. This condition seems to be associated with the interval 



