ENERGY SUPPLY OF THE CELL 



139 



Table 27. — Influence op Arsenic upon the Fermentation by 



Zymase 

 (Total CO2 in grams) 



(1920) found the rate of respiration of Penicillium to be 

 constant between pH 8 and 4. If the acidity was 

 increased beyond pH 4, the rate of respiration increased 

 at once, but dropped soon below normal. As the acidity 

 increases, the time to drop below normal becomes 

 shorter and shorter. Though Gustafson gives only 

 curves and no data, there is an indication of the Tam- 

 mann principle. 



A. Koch (1912) found decided stimulation of the 

 yeast fermentation by ether. The Tammann principle 

 could not be established with certainty. In some 

 experiments, the flasks with the largest doses of ether 

 gradually gained in fermentation, and finally fermented 

 most rapidly. Koch believed that the yeast became 

 gradually accustomed to the ether, but it may well be 

 that part of the ether had evaporated, and thus the 

 concentration of the stimulant approached the optimum 

 concentration. 



Stimulation of the rate of alcoholic fermentation by 

 using metal vats instead of wooden ones has been 

 claimed repeatedly. Zikes (1913) found that the CO2 

 produced by 1,000,000 cells was 0.748 in aluminum 

 vessels against 0.700 in glass vessels. 



