ENERGY SUPPLY OF THE CELL 



111 



They express the rate of reaction per hour, corrected 

 for the retarding effect of alcohol, and they should be 

 constant during the entire course of the fermentation 

 until the sugar concentration falls below 1.5%. This 

 is not quite the case. The computed data show a slow 

 but distinct decrease. Probably this is not due to the 

 inaccuracy of the data on fermentation, but to a gradual 

 deterioration of the zymase in the nitrogen-free sugar 

 solution. 



Other experiments by Rubner also show a fair agree- 

 ment with this formulation (see Table 18). Rahn 

 (1929b) verified it in a different way. He measured the 

 rate of fermentation in the presence of increasing amounts 

 of alcohol, using the CO2 pressure as indicator. Table 

 16 shows the average pressures obtained in three 

 experiments, and, further, the relative rates, based on the 

 unretarded rate as 100. 



If the percentage decrease of rate of fermentation is 

 proportional to the concentration of alcohol present, 

 there must be a straight-line relationship between the 



