198 
Journal of Agricultural Research 
Vol. XXXI, No. 2 
The inferior quality of the true fir seed renders these tests mainly 
of interest in showing results for the pine and Douglas fir. For these 
species the limit of heat under which the seeds remained viable 
was between 200 and 220° F. dry heat and considerably below that 
for moist heat. The fact, however, that one true fir seed germinated 
after the application of 220° of dry heat shows at least the possibility 
of seeds retaining their vitality under this temperature for several 
hours. 
From the fact that only one seed withstood intense heat success¬ 
fully one might conclude that seed subjected to the heat of forest 
fires in the cone (which would in some degree be moist heat) has 
small likelihood of retaining its viability. It must be remembered, 
however, that cones scorched by an ordinary crown flash are 
heated for only a short time, so that the seed rarely reaches very 
high temperatures. 
On the other hand, the comparatively low temperatures of the 19- 
hour tests that resulted in appreciable germination indicate that in 
a crown fire of devastating intensity there is small chance for the 
seed of any of these species to survive solely through the protection 
of cones while on the trees, although it may be possible that some 
seed will escape the fire in this way. 
Observations of the condition of the seeds during the heating 
tests may be briefly detailed as follows: 
SILVER FIR 
The silver fir seed in its normal condition has a glistening endo¬ 
sperm; brownish, translucent seed coats; and a smooth surface. 
The small blisters in the exocarp are well filled with pitch. When 
the seed was subjected to dry heat there was no apparent change 
until 140° F. was reached, when a slight drying of the seed was 
noticeable. At 160° the pitch began to ooze from the seed coats 
and the endosperm was slightly whiter. As the temperature rose 
higher, this drying of the endosperm became more and more ap¬ 
parent. At 200° so much pitch had exuded from the seeds that 
they began to stick together. This condition progressed until, at 
300° of dry heat, tfle seeds browned, and so much pitch had oozed 
out that they were stuck to the dish. 
.With the seed giyen moist heat, the only apparent change was 
the oozing of the pitch until, at the highest temperature, 240° F., 
the seeds stuck to one another, but not so much so as in the dry- 
heated seeds. No change in the endosperm in drying or in color 
was apparent. 
NOBLE FIR 
The normal noble fir seed has a smooth exocarp, with small pitch 
pockets well filled with pitch. The seed coats are translucent when 
taken separately; and the endosperm has a glistening color, but it 
usually does not fill the ovary. When the seed of the noble fir was 
dry heated, there was no change apparent up to 160° F. Then the 
exocarp turned darker and shmy, and this condition became more 
marked with the continued rise of temperature. At 180° there was 
an appreciable drying of oils in the endosperm. These conditions 
became more noticeable until, at 300°, the seed was shriveled, and 
a great deal of pitch exuded and the endosperm was darkened. 
