BIOCHEMISTRY OF STREPTOCOCCUS HEMOLYTICUS 215 



cent alcohol. This alcoholic solution was carefully evaporated 

 to dryness in a tared dish and dried at 130°C. to a constant 

 weight. An excess of H2SO4 was next added and the material 

 converted to BaS04 by ignition. From the weight of BaS04 

 obtained, the corresponding weight of lactic acid was readily 

 calculated. In case lactic is the only acid present the theoretical 

 yield of BaS04 may be estimated from the weight of dried barium 

 salt previously found. 



Experiment I. The volatile and non-volatile acids produced in 

 streptococcus fermentations 



One hundred and fifty cubic centimeters of broth were inocu- 

 lated with 6 cc. of a first-generation, glucose broth culture of 

 Streptococcus hemolyticus and incubated for eighteen to twenty- 

 four hours. Determinations of the volatile and non-volatile 

 acids were made upon 100 cc. of this culture in the manner 

 described. Control determinations were carried out upon a 

 sample of uninoculated broth. The following results were 

 obtained : 



Acids Broth 



Volatile (as cc. of n/10 acid per 100 cc. broth) 4.42 



Lactic acid (as grams per 100 cc. broth) 0.031 



The values shown in the table were applied as corrections in 

 the analyses of cultures. 



Of the numerous estimations which have been made the results 

 of but three will be presented: Culture (1), 1 per cent glucose 

 broth; culture (2), 1 per cent glucose broth; culture (3), 1 per 

 cent glucose, 5 per cent horse serum broth. 



The curves plotted from the "distilling constants" (shown in 

 table 2) proved to be so closely analogous that only one result 

 will be shown. From the position of the line (fig. 1) representing 

 the distilling rate of culture (1) it would appear that acetic acid, 

 chiefly, is elaborated by the streptococcus during its growth in 

 broth media containing either glucose or glucose plus horse serum. 

 A trace of formic acid may also be present. This conclusion is 

 the only one that may be drawn al; present even though the 



JODRNAl OP BACrERIOLOQY, VOL. VI, NO. 2 



