1921] SHERMAN—DORMANT SEEDS 23 
proteins was applicable as a temperature-life duration formula for 
wheat grains, as LEPESCHKIN himself had found it applicable for 
imbibed cells. Loss of viability in air-dry seeds, therefore, is 
probably due to “‘a time-temperature denaturing of certain colloids 
(probably proteins) of the embryo” (16). The retarding effect of 
carbon dioxide upon germination has been shown by Kipp (28). 
On the other hand, enzymes may persist and have a high degree 
of activity in seeds which are no longer viable, as in Amaranthus, 
or their activity may be greatly decreased without marked decrease 
in percentage of germination, as in Johnson and Sudan grasses 
(CrocKER 16). Exhaustion of stored food cannot be considered a 
cause for decreased life duration in air-dry seeds, but in the case of 
seeds lying in the soil the situation is different. Such seeds would 
have a high water content, favoring chemical action, whether 
respiration or digestion. The actual occurrence of such reactions 
of course would depend upon oxygen supply, temperature, enzymes 
present, and the extent to which by-products (carbon dioxide, etc.) 
were removed. In such seeds, of which Amaranthus is a typical 
example, the life duration might easily be limited by the amount 
of stored substance present or by the rapidity with which it was 
respired or digested. 
CROCKER and HARRINGTON (16), in studying the behavior of 
Johnson grass, found that storage of freshly harvested seed at 20° C. 
in the germinator led to an increased or secondary dormancy, a 
phenomenon frequently observed in seeds as a result of unfavorable 
germinating conditions. They suggest that such a deepened dor- 
mancy, if accompanied by a decreased respiration, may have an 
important bearing upon the longevity of seeds in the soil by 
lengthening the period necessary for the reduction of stored foods. 
From their own experiments on the respiration of Johnson grass 
they estimate the possible longevity of this seed as follows: 
If 75 per cent of the weight of the seed can be respired before death occurs, 
secondarily dormant Johnson grass seeds could lie in a germinator for 9.8 
years at 20°C. before death would occur from exhaustion of stored foods. 
The period at 10° C. would likely be 2 to 3 times 9.8 years, in accord with 
the temperature quotient for respiration. Without such a reduction in respira- 
tory intensity the possible longevity would be a little more than one-third as 
great, figured on the initial rate in the active seeds. Even if the longevity of 
imbibed seeds in the soil be dependent upon some contingent other than 
