July 15,1925 
Laboratory Tests on Effect of Heat on Seeds 
199 
In the moist-heat series this change of color was not so apparent, 
and the shriveling of the seed did not occur. 
WESTERN WHITE PINE 
The normal western white pine seed has an exocarp with a slight 
grayish bloom; the endosperm is very oily and smooth and fills the 
entire ovary. No changes were apparent until 160° F. was reached, 
when the exocarp began to darken, and the pitch began to ooze from 
the seed. These changes became more and more apparent as the 
temperatures became higher. At 200° drying of the endosperm 
became noticeable. At 240° so much pitch had oozed from the seed 
coats that the seeds stuck together and stuck to the dish. At 300° 
the exocarp was very brown and almost charred where in contact 
with the dish, while the drying of the endosperm was marked. 
The seeds subjected to moist heat did not show these changes of 
color or shriveling of endosperm, but the amount of oozed pitch was 
about the same. 
DOUGLAS FIR 
The normal Douglas fir seed has a mottled, dark-brown exocarp 
and a whitish clear endosperm which entirely fills the ovary. There 
was no change apparent until 180° F. was reached, when the exocarp 
became slightly darker, and shiny. This became more noticeable 
until, at 240°, the seeds had exuded enough pitch to stick together 
and stick to the dish. The endosperm did not show any change until 
240°, when it was noticeably drying out and slightly shriveled. At 
300° the exocarp was a very dark brown, the endosperm was notice¬ 
ably shriveled, and a great deal of pitch had oozed out. 
The seeds in the moist-heat series did not show this shriveling of the 
endosperm, and the change of color in the exocarp was not so marked, 
although about the same amount of pitch came from the seeds. 
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