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IOWA ACADEMY OP SCIENCE 
ally germinate more rapidly than the untreated. The whole subject has 
been discussed by Detmer."® 
Schroder"" has shown that barley containing only two per cent of water 
germinated well after an interval of twelve weeks, dost"" calls attention 
to the fact that seeds of the grass type which can withstand thorough 
drying as a rule retain their powers of germination only for a limited 
number of years. ‘‘What the laws of germinating power depend on 
in the long run is not known, but when we reflect that gradual altera- 
ing to reduce their solubility, we may conclude that speciflc pro- 
toplasmic bodies undergo as time goes on , alterations calculated to 
render them functionless. At all events it is quite out of the question 
to suppose that death of the resting seed is brought about by using up 
reserve substances in respiration. 
The writer some years ago made a test of corn kept under different 
conditions. One sample which germinated 100 per cent early in the 
spring, in the course of two months, subject to the various changes of 
the weather, dropped to 66 per cent. In another sample kept in the 
laboratory, the germination during the early spring was 98 per cent; 
kernels taken from the same ear two months later dropped to 80 per 
cent. The loss in vitality here was undoubtedly due to the absorption 
of moisture and respiratory changes that occurred in the seed, and 
Ewart"'* suggests that longevity depends not on food materials nor seed 
coats but upon how long the inert proteid molecules into which the 
living protoplasm disintegrates when drying, retain the molecular group- 
ing which permits of their re-combination to form the active protoplasmic 
molecule when the seed is moistened and supplied with oxygen. The 
same author further demonstrated'^'* that “seeds capable of withstanding 
thorough drying assume a perfectly dormant condition in which they 
do not respire and are not living although they have a power of restor- 
ing life potential in them for a longer or shorter period of years. ’ ’ And 
Becquerel concludes that only those seeds can preserve their vitality 
which have thick coats and are impermeable to water and oxygen and 
do not have a large amount of oxydizable reserve matter. This conclu- 
iGYergieichende physiologie des Keirnungsprocesses der Samen. 402. 
See also paper by Edwards and Colin, Ann. d. Sc. Nat. Bot. 1:264. 1834. 
Sachs Handbuch d. Experimental physiologie d. Pflanzen. 66. 
^^Unters bot. Inst. Tubingen. 2:1. 
^®Lectures on Plant Physiology, Eng. Trans, by Gibson. 342. 
^®Proc. Roy. Soc. of Victoria. 21:184, 1 pt. 
^"Trans Liverpool Biol. Soc. 8:234. 1894. 
