BOTANY: CROCKER AND GROVES 
153 
shown that the coagulation temperature of proteins is not a fixed point 
as is the melting point of metals and other substances. Coagulation is 
a function of duration of heating, percentage of water present, and the 
reaction of the protein as well as of the temperature. The lower the 
water content the more heating is required for coagulation. Acidity 
favors and alkahnity retards coagulation by heat. BugHa^ estabhshed 
the following time-temperature formula for the coagulation of pro- 
teins: T = a — b log Z, in which T = temperature in degrees Centi- 
grade, Z = time in minutes, and a and b are constants. 
If our surmise is correct that the loss of viability of seeds with storage 
is a matter of coagulation of cell proteins of the embryo, this time- 
TABLE I 
Record Sheet No. 21. Turkish Red Wheat 
April 10, 1914. Temperature 87.5°C. Moisture 12%. Percent germinated in heavy figures. 
Percent partially germinated in light figures 
Time, days for germination 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
Control < 
f 
0 
2 
2 
4 
3 
3 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
\ 
92 
92 
92 
93 
95 
95 
98 
98 
98 
98 
98 
98 
98 
98 
98 
98 
98 
98 
Heated for 7 minutes . . = 
0 
15 
12 
7 
8 
7 
8 
7 
5 
3 
3 
4 
4 
4 
3 
2 
\ 
2 
5 
27 
41 
49 
55 
61 
64 
67 
70 
72 
72 
72 
72 
73 
74 
4 
8 
8 
7 
8 
7 
5 
3 
5 
1 
1 
1 
0 
« « 8 " = 
\ 
5 
10 
25 
30 
35 
41 
47 
52 
54 
54 
58 
59 
59 
60 
2 
4 
4 
5 
4 
5 
4 
5 
2 
3 
6 
5 
4 
« « 9 » 
2 
4 
8 
10 
11 
18 
25 
28 
32 
34 
35 
37 
38 
" 10 " 
1 
3 
4 
6 
4 
3 
3 
4 
5 
0 
0 
0 
0 
4 
5 
9 
11 
11 
1 
1 
0 
0 
2 
1 
1 
1 
2 
4 
• 
4 
5 
> 
2 
2 
2 
2 
2 
0 
0 
0 
2 
2 
" 13 " 
0 
0 
0 
temperature formula for the coagulation of proteins should be appli- 
cable as a temperature-life duration formula for seeds. In experiment, 
of course, the life duration determined must be at relatively high tem- 
peratures in order to make the time within the range of an experiment. 
This calls for temperatures ranging from 50-100'^C. for air dry seeds. 
So far we have used the method of reflux of ethyl or methyl alcohol 
or mixtures of these with water as a means of obtaining constant tem- 
peratures. This gives a range of temperature from about 65— 99°C. 
and a variation at any temperature of less than ^ 0.1°C. Delayed 
germination and lack of resistance of heated seeds to fungal attack 
made sterilization imperative. Silver nitrate to an aqueous solution 
of which the coats of various seeds are impervious proved an effective 
sterilizing agent. 
