Sept. i6, 1918 
Resistance of Seeds to Desiccation 
527 
of 7 days and that at the end of 28 days was used as a measure of the 
germinating energy. With a lot of seed which germinated more slowly 
all germination tests were continued for 35 days, and the ratio 14 to 35 
days was used to express the germinating energy. 
The series of experiments described in the following pages was begun 
on January 12, 1917. Two varieties of barley, Hordeum vulgare T.; two 
varieties of wheat, Triticum aestivum L. (T. vulgare Vill.); a sample of 
Sudan grass, Holcus halepensis sudanensis (Piper) Hitchcock ( Andropogon 
halepensis sudanensis Piper); and one of Johnson grass, Holcus halepen¬ 
sis I/. (Sorghum halepense Pers.) were stored at room temperature in 
evacuated desiccators over calcium oxid and over concentrated sulphuric 
acid. Prom the seeds in these desiccators and from control lots stored 
in an open vessel in a desk drawer samples were withdrawn for moisture 
determinations and germination tests at intervals during the next 10X 
months. Germination tests of Johnson grass seed were made with a 
daily alternation of temperatures between 25 0 and 40° C. All tests 
were continued for from 9 to 17 days. Germination tests of all other 
seeds were made at 20° C., and the length of the tests varied from four 
to six days, germination being practically completed in four days. In 
all germination tests moist blotting-paper disks inclosed in 100-mm. 
petri dishes were used for germinating beds. The results of moisture 
determinations and germination tests are summarized in Tables I, II, 
and III. 
Table I .—Moisture content and percentage of germination of Svanhals barley and 
Johnson grass samples after storage for different lengths of time over lime and over sul- 
phuric acid, compared with samples stored in an open vessel 
Date of 
test. 
Length of time stored 
under different condi¬ 
tions. 
Svanhals barley. 
Moisture content (percentage 
of dry weight). 
v - 
Germination (per cent). 
Stored 
over 
calcium 
oxid. 
Stored 
over 
sulphuric 
acid (sp. 
gr. 1.84). 
Stored 
in open 
vessel. 
Stored 
over 
calcium 
oxid. 
Stored 
over 
sulphuric 
acid (sp. 
gr. 1.84). 
Stored 
in open 
vessel. 
igiy. 
Jan. 12 
0 1 
Feb. 26 
6 weeks... 
d. I 
y- x 
07 
06 
99 
95 
Apr. 2 
11 weeks. 
O' *T 
2 . 7 
*T x ' 
2, O 
y / 
06 
9 U 
00 
May 3 
16 weeks. 
I- 5 
y 
1.8 
8. 2 
yvj 
97 
yy 
100 
99 
June 19 
23 weeks. 
7 
1.9 
11. 8 
95 
94 
98 
July 12 
6 months. 
I. I 
i. 3 
12. 1 
96 
98 
98 
Aug. 8 
7 months. 
. 7 
. 0 
95 
07 
98 
<V7 
98 
r \*7 
Sept, k 
8 months. 
• y 
Nov. 25 
10X months. 
• 
.8 
*7 
9-4 
y / 
98 
91 
96 
9 / 
96 
