THE ROLE OF OXYGEN IN GERMINATION 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 181 
CHARLES Ac SHULL 
A study of the respiration of Xanthium seeds was undertaken 
some time ago with the purpose of determining whether there was 
any change in the permeability of the seed coats to oxygen during 
the period following the normal ripening of the seeds. Some 
evidence was noted previously’ that there was either a change in 
permeability of the seed coat, or a change in oxygen need of the 
embryo during the early winter, and it was believed that a careful 
measurement of the oxygen used by the seeds with coats on and 
off at successive intervals during the year would show which of 
these changes occurred, and at what period of the ripening process. 
Circumstances have prevented the carrying out of this series of 
tests; but the preliminary results are of sufficient interest in con- 
nection with the rdle of oxygen in germination behavior to warrant 
placing the data on record. The measurements were made with 
a respirometer of excellent type designed by Dr. WitL1AM CROCKER, 
to whom I am further indebted for suggestions regarding the 
problem. The respirometer was kept in a Freas thermostat at 
25.25 C., and the volumes of oxygen used are reduced to standard 
conditions. Seeds of X. glabratwm in dry storage for nine months 
were used. 
First it was necessary to know what part of the oxygen was 
used by the coats under ordinary atmospheric germinative con- 
ditions. Two lower seeds were placed in one chamber of the 
respirometer, and the coats of two lowers in the other chamber. 
In 22.5 hours the two seeds used 0.475 cc. of oxygen, while the 
two coats used 07098 cc. From the results of BECQUEREL’s work* 
I had suggested that the coats were probably responsible for a part 
*Sautt, Cuas..A., The oxygen minimum and the germination of Xanthium 
seeds. Bort. Gaz. 52:453-477. IgII. 
? BECQUEREL, Paut, Recherches sur la vie latente des graines. Ann. Sci. Nat. 
Bot. IX. 5:193-320. 1907. 
Botanical Gazette, vol. 57] [64 
