142 



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



was proportional to this oxygen charge. But all evidence seems against the 

 idea that any appreciable amount of oxygen is stored up. It is therefore 

 suggested that the effect of oxygen is that of a stimulus to growth and 

 ferment production, and the effect of such stimulus in modifying the 

 subsequent fermentation has been seen in the experiments described in this 

 communication. A little air introduced at the beginning can give rise to a 

 very marked effect upon the whole subsequent course of the fermentation. 

 In the last two experiments described in this communication, namely I> 

 and E, the conditions were practically the same, except that by accident air 

 was momentarily admitted to E, there has followed a large increase in acetic 

 acid and diminution of carbon dioxide. 



Again it is frequently observed that fermentations which refuse to begin 

 can be made to do so by the introduction of a little air. Pakes has also 

 observed this with formic acid fermentations by various bacteria. Lately we 

 have observed the same, both with formic acid fermentations and with 

 glycerol fermentations. 



Oxygen thus appears to be a stimulus to fermentation production by 

 certaiu bacteria as by yeast. The effect long outlasts the stimulus and is not 

 proportional in any chemical sense to it. This is probably the explanation of 

 the oxygen charge of Horace Brown. 



Conclusions of Section A. 



Anaerobic fermentation of glucose by an emulsion of B. coli communis- 

 proceeds differently according as the organisms have been grown previously 

 with or without oxygen. 



When the immediate past history has been anaerobic, the fermentation 

 under anaerobic conditions yields very little or no lactic acid and greatly 

 diminishes succinic acid. In place of these, acetic acid appears in large 

 proportion. Admission of oxygen during the fermentation leads to lactic 

 acid production. The fact that acetic acid replaces succinic acid entirely 

 gives additional proof of the close relationship of these two substances. 



The results also confirm the conclusions of the earlier sections as to the 

 independence of the lactic acid, acetic acid, and probably of the carbon 

 dioxide fermentations. 



Section B. 



In this Section the effect of admitting oxygen during the fermentation is 

 considered in more detail. Eight experiments are described. In the first 

 four, a solution of peptone and glucose was fermented by the introduction of 

 a small seeding of bacteria. In the second four, an emulsion of bacteria,. 



