MECHANICS OF DORMANCY IN SEEDS 
103 
from 9 to 12 percent moisture showed a coefficient of 7 to 8, and that 
containing 18 percent moisture 10 to 16 for 10° C. rise in temperature. 
For life duration of barley seeds, containing considerable moisture, 
Goodspeed got a coefficient of 10 to 16 and Loeb and Moore on various 
sea forms found coefficients ranging from 500 to i ,450. It is interesting 
to compare the above temperature coefficients for life duration with 
those for the coagulation of various proteins. The latter vary from 
6 to 635 according to the range of temperature, moisture content and 
protein used. 
The evidence is good then that at temperatures above 50° C. , with air- 
dry seeds or those containing somewhat less or considerably more water, 
the loss of viability is a matter of the denaturing of embryo proteins. 
What about loss of viability at laboratory temperatures and tem- 
peratures prevalent in natural conditions? When we compare the 
longevity of wheat, containing 12 percent moisture, as calculated 
from our measurements at high temperatures either on the basis of 
the Lepeschkin formula or of the temperature coefficient found, the 
values are of about the same magnitude as those observed for wheat 
by White.ii There is still need of much work on several long-lived 
and short-lived seeds of which we have fairly reliable records of 
longevity, to see whether the calculated longevities from measurements 
at high temperatures by the two methods mentioned above, tally 
well with observed longevities. 
To make concrete the indicated significance of temperature in 
longevity of seeds let us assume that wheat with a fixed water content 
at 20° C. has a longevity of 16 years and that the temperature co- 
efficient of 8 still applies at low temperatures. On these assumptions 
the longevity at 30° C. would be two years, at 10° C. 128 years and at 
0° C. 1,024 years. 
The total of our results gives considerable grounds for believing 
that at low and equable temperatures and moisture contents medium- 
lived grains like wheat may retain their vitality several centuries. 
I am confident, however, that this coagulation theory of longevity 
has much greater value in opening a line of attack than in matters 
already established. 
The statements above apply to seeds approaching the air-dry 
"White. Proc. Roy. Soc. London 81 B: 417. 1909. 
^2 It is probable that the action of oxygen as well as noxious gases must be 
avoided. Becquerel. Ann. Sci. Nat. Bot. IX 5: 193. 1907. 
