Brown. — Some Studies on Yeast. 
22 1 
a satisfactory series of values for the temperature-coefficients over a range 
from 5 0 C. to 35 0 C. 
The coefficients are large, but diminish with increasing temperature : 
for instance, a rise of temperature from 5 0 C. to io° C. results in the fermen- 
tation at the higher point being 2*65 times as rapid as at the lower ; whereas 
raising the temperature from 30° C. to 35 0 C. results in an increased rapidity 
of only i*35 times. He also found that these coefficients are remarkably 
similar for brewery yeasts, distillery yeasts, and wine yeasts, so much so in 
fact that he was led to regard the temperature-coefficient as characterizing 
certain constant properties of the enzyme zymase , which is common to all 
alcoholic yeasts. 
The following Table gives the temperature coefficients, as determined 
by Slator, for brewery yeasts (top fermentation) ; they are expressed as 
quotients for 5 0 C. : 
Table II. 
Temperature quotients for brewery yeast. 
V io°/V 
V i5°/V io° 
V 2o°/V 1 5 0 
V 2 5 °/V 20° 
V 3 o°/V 25 0 
V 35°/V 30 ° 
V 4 o°/V 35° 
2-65 
2*11 
i*8o 
i-57 
i-43 
i'35 
1 • 20 
By making use of the above Table of temperature coefficients, taken 
from Slator’s paper, and expressing as unity the amount of sugar fermented 
in a brief interval of time at 5 0 C. through the agency of a definite number 
of yeast-cells per unit volume, we can obtain a series of values which 
represent the progressive rates of fermentation expressed as a function of 
the temperature between 5 0 and 40° C. The values which I have recast in 
this way are given in Table III, and are also represented graphically in the 
curve of Fig. 8, 
Table III. 
nferature . 
Rates of fermentation. 
At 5 0 . 
. . 1 a oo 
IO° . 
2-65 
l5 o 
5-59 
20 
10-05 
25 o° • 
15*80 
3 °0 ’ 
22*59 
35 ° 
30*50 
40 
36*60 
Since this curve (Fig. 8) is based on true temperature coefficients, we 
can ascertain by means of its use the effect which any given rise of tern- 
