Nov. 1,1925 
Stimulating Germination of Western White-Pine Seed 895 
Table III. — Results of freezing in air and snow , with and without soaking in water 
Group 
No. 
A. 
B. 
C. 
D 
E. 
F. 
G. 
H 
I. 
No. 
Treatment 
J-Freezing in air, not soaked_ 
Tips cut... 
|Freezing in air, all soaked before freezing. 
Tips cut____ 
J-Freezing in air, soaked after freezing__ 
Tips cut.... 
|Freezing in air, soaked before and after freezing... 
J-Freezing in snow, not soaked.__ 
Tips cut__ 
J-Freezing in snow, soaked before freezing... 
Tips cut..... 
|Freezing in snow, soaked after freezing .. 
Tips cut-- 
|Freezing in snow, soaked before and after freezing 
J-Check tests, not frozen, not soaked_ 
Tips cut__—. 
Percent¬ 
age of 
germi¬ 
nation 
in 50 
days 
3.5 
4.0 
3.0 
17.5 
6.5 
10.2 
6.5 
7.5 
11.5 
15.5 
11.0 
5.0 
5.5 
8.5 
6.5 
6.0 
4.5 
5.5 
5.5 
10.0 
6.5 
7.5 
5.5 
6.5 
15.0 
The soaked seed was immersed in cold water for 24 hours, and all 
of the samples except those used for checks were then exposed for 
40 days, from February 22 to April 3, and tested in sand in the 
greenhouse. While complete greenhouse germination of this species 
requires 200 days, and is usually at a maximum after 100 days, these 
tests were concluded after 50 days in order to bring out more clearly 
the stimulating effect. A record of the daily temperatures during 
exposure of the seed is given below. 
Temperature 
Feb. 22-29 
Mar. 1-15 
Mar. 16- 
Apr. 3 
Mean maximum.___. 
37 
35 
41 
Minimum_ _ _ ___ ___ 
21 
25 
28 
High_ __ 
41 
44 
48 
Low ... 
14 
6 
22 
In Groups A to D, the highest germination (17.5 per cent) resulted 
from soaking 24 hours followed by air freezing; the next highest 
germination was 15.5 per cent, resulting from air freezing and soak¬ 
ing both before and after freezing; only 7.5 per cent germination re¬ 
sulted from soaking after air freezing; and germination in the check 
tests was from 5.5 per cent to 6.5 per cent. This indicates that 
germination may be hastened by this means and that soaking before 
freezing is more influential than soaking afterwards. 
Better results were also obtained by soaking before freezing when 
snow was used, but germination was not so high as by air freezing. 
There was no noticeable difference between those not treated and 
those soaked after freezing. 
Since the best results in this series of experiments exceeded those 
with the tips cut, which in previous tests had given the highest 
