148 



Messrs. E. C. Grey and E. G. Young. 



occur depends upon the production of nascent hydrogen, either from formic 

 acid or its precursor. It would appear, therefore, that the effect of oxygen is 

 to inhibit the mechanism for the utilisation of nascent hydrogen. Clearly 

 also, since the total formic acid CO3 and H2 is diminished, it is likely that 

 there is less hydrogen available. These experiments would seem to prove 

 conclusively, therefore, that a constant amount of alcohol is produced by the 

 decomposition of B. coli on glucose by a fermentation in which nascent 

 hydrogen plays no part, but that an increase in this alcohol production 

 frequently occurs under circumstances where nascent hydrogen is operative. 

 Likewise for acetic acid there is a tendency for a certain constant production 

 in equimolecular proportion to the alcohol, but nascent hydrogen may 

 diminish and oxygen increase its yield. If we try to explain the mechanism 

 by which alcohol and acetic acid arise, we seem to be led again to the 

 Cannizaro reaction. 



Calculation of the Oxygen in the Products of Anaerobic and Aerobic Fermenta- 

 tion as compared to the Oxygen in the Glucose fermented. 



It is surprising to find that if the oxygen is calculated for each of the 

 products of the fermentation, more is found than corresponds to the glucose 

 fermented, and corresponding with this gain in oxygen, there is a loss of 

 carbon and slight loss of hydrogen. The gain of oxygen and loss of carbon is 

 much more marked in the anaerobic than it is in the aerobic fermentation. 



We give the results of two anaerobic and two aerobic experiments calcu- 

 lated out to show these facts in Table V. No account is taken of lactic acid 

 and acetic acid, since these have the same empirical formula as glucose. 



As explanation, we can only suggest that water has been added on in the 

 reaction. Further work must be carried out to explain the facts with 

 certainty. 



It may be noted that this gain of oxygen and loss of carbon in the products 

 analysed is not observed in the present analyses only, but in all the previous 

 ones. The results given by Harden earlier show the same relationships, also 

 in the cases we have calculated, and, as a matter of fact, in his first paper on 

 this subject, Harden postulated water as taking part in the reactions and 

 entering into the final products. 



Conclusions to Section B, 



The effect of introducing oxygen in the fermentation of glucose by B. coli 

 communis is to increase the lactic, acetic, and succinic acids, and to diminish 

 the hydrogen, carbon dioxide, and formic acid, but to leave the alcohol 

 unchanged. 



