1914] ATWOOD—GERMINATION OF AVENA 401 
puted for the various periods tested. The two chambers served to 
check all readings. It was found that quite consistent rates were 
obtained. The rates of oxygen absorption were measured with the 
bath at the temperature of 21° C 
Before considering the data derived from the respirometer 
readings, it must be 3 
borne in mind that “ 
one of the objects 
sought is to gain a 
clearer idea of any 
changes which may 
occur in the embryo 
during the after- ,22 
ripening period. The é 
gas absorption meas- 
urements are for the « 
whole seed, of which 8 . 
the embryo forms, by _ e 
weight, a small part. mS aed 
Hence any variation -!4 
in the corrected read- 
ing for the whole seed 
Might indicate a far 
greater comparative 
variation for the em- — 
bryo. Stowarp (63) 
has compared the sahtende: . ae a 
respiration of the ae sins Gatembn acetone heeraeees 
separated endosperm of cc. per hour per gm. dry weight; rate for intact 
and embryo of barley. seeds, solid line; for seared seeds, broken line. 
He finds that per 
Sram of fresh weight, the respiration of the embryo alone is 17 
times that of the endosperm, but as the endosperm weighs about 
17 times as much as the embryo, these parts probably about halve 
the respiration of the intact seed. To reason from the respiratory 
behavior of the separated units to the nature of the respiration 
of the intact seed seems sufficiently uncertain to justify at least 
ray 
UV 
