The Enzymes o/B. coli communis. 



143 



previously grown on agar, was employed. The eight experiments con- 

 stitute four pairs, in each of which there is an aerobic and an anaerobic 

 fermentation. In the former case, about 2 litres of air were admitted in 

 forty-eight hours. About 5 grm. of glucose was fermented in each experi- 

 ment. Further experiments, carried out with more efficient aeration, would . 

 be of interest. 



Experimental. 



In the first four analyses a solution of glucose and peptone was fermented. 

 In A and B the glucose was present when the flasks were inoculated. In C 

 and D the glucose was not added until twenty-four hours after the inocula- 

 tion of the peptone. 



Experiment I. — The solution contained : — peptone, 5 grm. ; glucose, 5 grm. ; 

 saline,* 500 c.c. ; chalk, 5 grm. 



- After seventy-two hours the glucose was found completely fermented. 

 The results of the analyses are recorded in Table I. 



Table I. — Products Expressed as Percentages of Glucose Consumed. 



Products. 



A (anaerobic). 



B (aerobic). 



Kydrogen 



Carbon dioxide 



Alcohol 



Total 



0-231 

 34 -22 \ 35 -70 



1 -25] 



8-91 

 10 -68 



3-94 

 22 -45 



0-131 



15 -90 \ 24 -51 



8 -48 J 

 17 -57 

 37 -57 



4-73 

 10 -17 



81 -68 



94-45 



These analyses show that the introduction of oxygen during the fermenta- 

 tion leads to : — diminution of hydrogen, diminution of carbon dioxide, 

 diminution of formic acid, diminution of alcohol ;f and to increase of lactic 

 acid and increase of acetic acid. 



Experiment II. — A second pair of fermentations was carried out at the 

 same time, and with the same sowing of bacteria as in Experiment I ; but 

 the glucose was not added until twenty-four hours from the time of 



* Saline solution contained 0-6 per cent. KjSO^ and O'l per cent. MgS04. 



t It is probable that in this analysis it is not that the oxygen has diminished the 

 alcohol, for 10 per cent, is quite an average yield under normal circumstances. Some 

 other factor has led to an increase of alcohol in A above the normal. This large yield of 

 alcohol is evidently to be correlated with the great diminution of formic acid, and it 

 shows that alcohol is formed in relation to the utilisation of hydrogen. 



