\ 



Glucose and Mannitol by B. coli communis. 97 



Besult of Analysis of the Fermentation Solution at tlte end of the First Period of 



12 Hours. 



grm. gi'Di- 



Weight of sugar fermented 10 78 



Products found — 



Carbon dioxide 2"43 



Formic acid 1*09 



Acetic acid 3-40 



Succinic acid 0'72 



Lactic acid O'lO 



Ethyl alcohol 3-56 



Hydrogen, 420 c.c. at KT.P 0-04 



11-34 



Eatio CO2/H2 1-4 



This result is of considerable importance, for it shows that during the 

 period of death of the bacteria the production of lactic acid ceases. The 

 fact that ethyl alcohol, acetic acid and (formic acid + carl:)on dioxide), each 

 represent about a third of the sugar fermented, and that the proportion between 

 these substances is the same as when the fermentation is carried out under 

 very different conditions, spea'k strongly in favour of the view already put 

 forward as to the origin of these substances in common from a single inter- 

 mediate substance, and by the action of the same enzyme. The fermentation 

 during the first period has in fact occurred in the manner which was to be 

 expected from the experiments described in Part II provided it were 

 possible to exclude the action of the lactic-acid-producing enzyme, a 

 resiilt which has here been achieved. It has been shown in Part II that 

 succinic acid has an origin probably in common with acetic acid and that 

 the two substances coiild replace one another ; it requires therefore no 

 change in the writer's hypothesis to account for the variations in the amount 

 of succinic acid produced in these experiments. 



Here, as in the earlier experiments of Harden and later also of the writer, 

 the tendency is seen for the alcohol and acetic acid to be produced in equi- 

 molecular proportions. 



In order to ascertain the proportion of the products formed during the 

 subsequent periods of the fermentation, it is necessary to subtract from the 

 amounts of the pri)ducts found in each period the amounts of such substances 

 which were present at the commencement of the period under consideration. 

 These results may be deduced, from a study of fig. 2, which is a graphical 

 record of the rate of formation of the various products of the fermentation. 



