ENERGY SUPPLY OF THE CELL 



105 



at 30°C. by a good compressed yeast varies from 570- 

 660 c.c. (Henneberg, 1926, I). This corresponds to 

 30 c.c. of CO2 per gram of yeast per hour, or about 120 

 mg. of CO2 (or of alcohol) per gram per hour. 



Henneberg gives also the following data for other types 

 of yeast: 



Table 13. 



-Volume of CO2 Produced by 10 Gm. op Yeast in 400 C.c. 

 OF A 10% Sucrose Solution 



For further data with bread yeast see p. 238, Table 65. 



Rubner's (1913) experiments give about 0.4 gm. of 

 sugar fermented per gram of yeast per hour; this corre- 

 sponds to 200 mg. of CO2 per gram yeast per hour (see 

 Table 15, p. 108). 



From Rubner's data that 5 gm. yeast = 38,700,000,- 

 000 cells, we obtain a CO2 production of 258 X 10~^° mg. 

 or a sugar consumption of 510 X 10~^° mg. of sugar per 

 cell per hour. 



Another fermentation whose rate has been studied in 

 some detail is the lactic fermentation. Rahn (1911) 

 mentions a number of experiments by Marshall and 

 Farrand (1908) from which he computed the fermenting 

 capacity by the formula mentioned above. He also 

 made experiments of his own. The data given in Rahn's 



