CHANGES PRODUCED BY A SAPROPHYTIC ANAEROBE 387 



of the laboratory was high (usually 25 to 35°C.), a correction for 

 ammonia was necessary. 



The following method was used in making these corrections. 

 A 2 per cent peptone solution containing known amounts of 

 standard ammonium hydroxide was placed in the Van Slyke 

 apparatus and the amount of nitrogen determined in the usual 

 manner. The difference between the peptone solution alone and a 

 peptone solution plus ammonia was considered to be due entirely 

 to ammonia. 



Van Slyke states that about 15 per cent of the ammonia nitro- 

 gen present will be determined as amino-acid nitrogen at 20'C. 

 in fifteen minutes. We obtained the following percentages by 

 averaging the results obtained from duplicate determinations 

 made on different dates. 



Per cent of ammonia nitrogen that would be recorded as amino- 

 acid nitrogen at different temperatures for the time used (five 

 minutes). 



At21°C. = 34.2 per cent 

 At23°C. = 39.6 per cent 

 At 25°C. = 44.9 per cent 

 At 27°C. = 50.6 per cent 

 At 29°C. = 55.7 per cent 

 At31°C. = 61.1 per cent 

 At 33°C. = 66.3 per cent 

 At35°C. = 71.6 per cent 

 C. = 77.0 per cent 



At 37 



This means that the above per cents of the total ammonia nitrogen 

 present would be recorded as amino-acid nitrogen at the various 

 temperatures recorded. 



It will be noted that these figures are considerably higher than 

 those recorded by Van Slyke. The results obtained give a fairly 

 uniform curve and were obtained under our experimental condi- 

 tions. Of course, they were obtained by the use of a compara- 

 tively simple mixture, while in actual tests we were deaUng with 

 an extremely complex mixture. However, all the fermentation 

 mixtures were different and it would have been impossible to 

 simulate them closely. 



