222 
Brown . — Some Studies on Yeast . 
perature would have on the rate of fermentation where the data have been 
previously obtained at any lower temperature. It can, for instance, be 
applied to any of the experiments recorded in Table I. Only one or two 
examples are necessary. 
In the first experiment, recorded in Table I, in which the mean tem- 
perature of fermentation was 14-3° C., it was found that the maltose which 
was fermented per 100 c.c. per hour by 1 grm. of yeast (10 cells per unit 
volume) amounted to o- 1 04 grm. Let us see what the amount of maltose 
fermented would have been under precisely the same conditions if the tem- 
perature had been raised to 30° and 40° C. respectively, and how this would 
have affected (a) the time required for a yeast- cell to ferment its own weight 
Fig. 8. Graphical representation of Table III, showing influence of temperature on fermentations. 
Amount of sugar fermented at 50° C. is taken as unity. Deduced from A. Slator’s temperature 
coefficients for brewery yeast. See Table II. 
of the sugar, and ( b ) the potential rise of temperature of the cell under 
adiabatic conditions. 
On reference to the curve, we note in the first place that the ordinate 
of temperature corresponding to 14*3° C. cuts the curve at the co-ordinate 
5-2, and that the ordinate corresponding to a temperature of 30° intersects 
the curve at 22 -6. The amount of maltose fermented at 30° will therefore 
22-6 X 0-104 
be 
5*3 
0-451 grm. per 100 c.c. per 1 grm. of yeast per hour; 
.*. the time taken for the yeast to ferment its own weight of maltose at 30° 
will be — - — = 2-2 hours, and the potential rise of temperature of the yeast- 
0.451 
cell in one hour under these new conditions will be ° = 75*5° C., 
o-oo 
instead of 15-1° C. 
In the same manner it can be shown that at 40° C. the amount of sugar 
fermented per hour, per 100 c.c. per 1 grm. of yeast, would be still further 
raised to 0-731 grm., whilst the time occupied by a cell in fermenting its 
