Glucose and Mannitol by B. coli communis. 



99 



Since the products add up to a greater weight than can correspond to the 

 ■sugar fermented, it is possible that the weight of the carbohydrate synthetised 

 by the bacteria cannot be quite accurately calculated from the reduction of 

 ■copper solution after hydrolysis. It is also possible that the additional 

 weight is derived from the organic matter introduced with the bacteria or 

 formed during the autolysis of the bacteria in the first period. 



But the conclusions which may be drawn from the analysis recorded above 

 are not affected by the fact that the products obtained are somewhat in excess 

 of the sugar used. The quantity of sugar which has been transformed or 

 synthesised into a form in which it does not reduce copper solution uutil 

 after hydrolysis represents about 70 per cent, of the original glucose. 



The great importance of this result will be considered later. For the 

 moment it will suffice to note the following facts with regard to this period of 

 the fermentation. 



It is essentially a period of synthesis. There is practically no production 

 either of alcohol or carbon dioxide or hydrogen. There is, as in the first 

 period, no formation of lactic acid. On the other hand, there is here a 

 formation of succinic acid in greater proportion to the acetic acid than in the 

 first period. 



The products formed during the third period, i.e. during the second 

 24 hours of the fermentation, were determined, as in the case of the second 

 period, by difference. 



The results were as follows : — 



Products of the Fermentation of Glucose formed during the Third Period, 



(24 to 48 Hours). 



grm. grm. 



Weight of glucose fermented 6'70 



Weight of non reducing carbohydrate fermented 4'98 



11-68 



Products found — 



Carbon dioxide , 0'34 



Formic acid 0'82 



Acetic acid 0'46 



Succinic acid 0'02 



Lactic acid 6"63 



Ethyl alcohol 1-05 



9-32 



Hydrogen not estimated. 



It will be seen that there is a loss here which almost corresponds in 



