Glucose and Mannitol by B. coli communis. 105 



several phases which can be separately studied if the period duriug which 

 the experiment is made is sufficiently short. These pliases are largely to be 

 correlated with increase and diminution in the number of living cells which 

 are present at any time. 



It has been shown that during the period which was characterised by 

 rapid death of the cells, there was no formation of lactic acid, whereas during 

 a period which immediately followed the rapid multiplication of the cells, 

 lactic acid was produced to the extent of 70 per cent, of the sugar consumed. 

 The period in which the cells died was characterised by the transformation of 

 sugar into alcohol, and formic, acetic, and succinic acids. 



Also it has been shown that at this period sugar is decomposed to a greater 

 extent than during the period of extensive multiplication, which points to the 

 conclusion that the fermentation is brought about by enzymes. 



During the period of multiplication there is a transformation of glucose 

 into a more complex substance which only reduces copper solution after 

 hydrolysis. The extent of the synthesis during this period is quantitatively 

 of the same order as the degradation which is brought about in the period 

 which follows. 



From these results the following general conclusions may be drawn : — 

 Elaboration of glucose into more complex material may occur during 

 certain phases of the life of bacteria to an extent exceeding the degradation 

 brought about during the same time, so that it were a fallacy to suppose 

 that bacteria are as a class concerned chiefly with the business of decom- 

 position. The degradations which these organisms set up are the sequel 

 of those processes of synthesis which are more immediately associated with 

 the growth and multiplication of the cells. In 48 hours a synthesis of 

 3 grm. of fat has been observed when less than a gramme of bacteria 

 was mixed with glucose under conditions unfavourable for the normal 

 fermentation process, and during a period of 12 hours accompanied by rapid 

 cell multiplication, a transformation of 7 grm. of glucose into a more 

 complex carbohydrate has been obtained. Thus it will be seen that the 

 synthetic side of the fermentation process brought about by bacteria has 

 been hidden because of the rapidity with which the processes of degradation 

 supervene. In order to study the process of synthesis the fermentation 

 must be interrupted as a rule before 24 hours have elapsed. 



The second general observation which may be made is with regard to 

 the existence of enzymes in bacteria. No one has doubted, since Buchner's 

 demonstration of the existence of zymase in yeast and of certain other 

 enzymes in bacteria, but that the fermentation processes brought about 

 by bacteria and other organisms were the result of enzyme action. 



