268 Prof. Potter. Electrical Effects accompanying the [July 14, 



and the recovery of the potential difference after separating the leads. 5 grm. 

 of yeast were used, and a 10-per-cent. solution of glucose at 28° C, the short 

 circuits being made at intervals of 15, 22, 36, 60, and 78 minutes after the 

 introduction of the yeast. 



Enzymes. 



The important part which enzymes play in the activity of yeast during the 

 breaking down of sugar into alcohol and C0 2 naturally leads one to an 

 inquiry as to any electrical effects which may accompany their action, and to 

 look for any such effects accompanying hydrolysis. At present I have had 

 little opportunity for extended observations on this interesting question, but 

 it may be worth while to record the results so far obtained. The two 

 enzymes — invertase and diastase — with which some work has been under- 

 taken, both exhibit distinct electrical response, though in a much smaller 

 degree than has been already described. 



Invertase. — For the study of invertase, a quantity of yeast was ground in a 

 mortar with sand and lixiviated with a small quantity of water. After 

 filtration through paper the filtrate was passed through porcelain to ensure 

 that all yeast-cells were removed, and half of the solution was boiled to serve 

 as a control. 



Cells were charged with 5- and 10-per-cent. cane sugar, and the invertase 

 solution added. In both cases a small voltage was registered, 0"02 for the 

 5-per-cent. and - 03 for the 10-per-cent. The development of the E.M.F. 

 was very gradual, and it was only after 70 minutes that the above readings 

 were recorded. Treatment with Fehling's solution showed that inversion had 

 taken place. No E.M.F. could be detected with the control cells to which 

 the boiled solution was added, and tests with Fehling showed that the 

 invertase had been destroyed. 



Diastase, — A similar cell charged with a 0"5-per-cent. starch emulsion, to 

 which was added 10 c.c. of a 5-per-cent. solution of diastase, gave an E.M.F. 

 of - 05 volt. The gradient of the curve of the potential development was 

 again very gradual, a voltage of - 3 being reached in ten minutes, after which 

 it slowly increased. 



Thus, in the hydrolysis of the polysaccharose starch to the monosaccharose 

 glucose and fructose, a larger E.M.F. is produced than in the hydrolysis of 

 the disaccharose cane sugar to the same monosaccharose. 



Hydrolysis of Cane Sugar by means of Sulphuric Acid. 

 For this experiment a cell was charged with a 1-per-cent. solution of 

 sulphuric acid. It was found that if water were added to either the inner 



