222 LAURENCE F. FOSTER 



in (2). When the 5 per cent horse serum is in the presence of 

 1 per cent glucose, however, no increase in NH3 is manifest 

 ((6) in the table) showing that the sugar shields the protein from 

 attack in this instance. 



Experiment III. The protein and carbohydrate metabolism of 



Streptococcus hemolyticus in broth containing (1) glucose 



and (2) glucose plus horse-serum^ 



Three hundred cubic centimeter lots of media of the following 

 composition were prepared from beef infusion broth, Ph 7.3: 

 (1) 1 per cent glucose broth; (2) 1 per cent glucose, 5 per cent 

 horse serum broth; (3) same as (2). 



(1) and (2) were inoculated with 12 cc. of an eighteen-hour, 

 second-generation culture from pleural fluid no. 198 in 1 per 

 cent glucose-broth. (3) was inoculated with an equal amount 

 of an eighteen-hour, first generation culture of the so-called 

 laboratory strain. This culture differs from the pleural fluid 

 culture in that it has been repeatedly transplanted upon artificial 

 culture media since the original isolation, whereas the latter has 

 been passed many times through rabbits. Both cultures were 

 carried in this experiment in order to determine if repeated 

 transplantation upon artificial culture media had brought about 

 changes in the strain which might appear as an alteration of some 

 phase of its metabolism. 



The following determinations were carried out upon samples 

 removed with aseptic precautions at intervals of three hours: 

 (1) Bacterial counts; (2) Ph; (3) glucose; (4) ammonia; (5) 

 amino acids; (6) hemotoxin. 



The experiment extended through a period of twelve hours. 

 Table 5 contains the experimental data. 



The curves of growth, acid^ formation and glucose utihzation 

 in the three cultures are found in figures 2, 3, and 4. It will be 



2 The writer desires to express his appreciation for the assistance rendered 

 by Dr. Marjorie W. Cook and Miss Bernice Rhodes in carrying out this 

 experiment. 



' The term acid is used to express true acidity in terms of Ph. 



