1914] ATWOOD—GERMINATION OF AVENA 407 
the limitations to oxygen entry, if rate of absorption be taken as a 
basis of judgment. 
7. DETERMINATION OF EMBRYO ACIDITY.—Investigation has 
been begun as to variations in the acidity of the embryo in after- 
ripening, and comparisons have been made with the embryos of | 
mi sativd. To test... 
this condition, the ~ , 
seeds were soaked 
Over night in the ice Se Wk 
box, and then sub- re y 
jected to identical Z 
germinative con- WY 
ditions for about 18 +22 zt’ 
hours. The embryos Fred 
were then removed, A. if 
accurately weighed, 8 
carefully ground, and 8 / 
: : : me 
immediately titrated 
with N/2o0 alkali in 
the presence of phe- 
nolphthalein. Water 
content of the em- 
bryos was determined 
on other parallel neta 
samples, from which 
data the dry weight 06 10 Hours 30 50 
of the titrated em- Fic. 13.—Rates of oxygen absorption for wild 
bryos could be com- oats in ce - a of oxygen diac go 8 
. : su uent €r-fl 
the mimber of eof AED emy wet tes init i 
in spring, broken line 
N/2o alkali necessary : 
to neutralize the acidity of the equivalent of one gram dry weight 
of the embryos, the results given in table VII were obtained. 
_ It will be noticed that the 1912 samples grown at Chicago were 
tested early and were less acid than corresponding year old 
samples of both the tame and of the wild. Further, the acidity 
is less in A. fatwa seeds one year old than in A. sativa just harvested. 
