92 



Mr. E. C. Grey, Decomposition of 



variation in the proportion of the products may be obtained by varying the 

 conditions. 



With regard to the results of exactly comparable experiments with 

 mannitol, good evidence has been obtained in confirmation of the view 

 already put forward by the writer that the fermentation of various carbo- 

 hydrates and allied substances by bacteria is brought about by a single set of 

 enzymes whose actions are common to all such cases of fermentation. This 

 does not exclude the possibility that the first step in the degradation of a 

 particular molecular structure may require a special enzyme in order to 

 produce the first intermediate substance, which according to the writer's 

 hypothesis would be the same for all analogous eases of fermentation. 



The Enzymes Concerned in the Decompositio7i of Glucose and 

 Mannitol by Bacillus coli communis. Part III. — Various 

 Phases in the Decomposition of Glucose by an Emulsion of 

 the Organisms. 

 By Egerton Charles Grey (Beit Memorial Eesearch Fellow). 

 (Communicated by Dr. A. Harden, F.R.S. Received July 25, 1917.) 

 (From the Laboratory of Prof. A. Fernbach, Institut Pasteur, Paris.) 



CONTENTS. 



PAGE 



Apparatus for the Study of the Various Phases of a Fermentation 93 



Details of an Experiment in which the Products of Fermentation have 



been Examined at Successive Stages 95 



General Considerations 102 



Summary and General Conclusions 104 



In Part II of this series 'results have been described which indicate the 

 existence of several independent processes occurring during the one experi- 

 ment. The experiment which will be now described was undertaken with 

 the object of simplifying results by shortening the time of the fermentation. 

 Arrangements were made also to count the bacteria at various periods, with 

 the object of determining how far the fermentation was due to enzyme 

 action which could be said to be carried on independent of the multiplication 

 of the cells. The plan of the experiment was as follows : — About 50 grm. 

 of glucose was to be fermented in a volume of 5 litres of solution. A 

 sample of about a litre was to be removed every 12 hours and submitted 



