90 -. EXTRACTING AND CLEANING FOREST TREE SEED. 
seed is slightly moistened with cold water. This may be done readily 
by putting the seed in a box, adding a little cold water and stirring 
with a shovel. 
Another application of the wet process is to pile the seed 6 or 8 
inches deep on a cement or plank floor, sprinkle it lightly with water, 
and then beat it energetically with leather flails. The wings can 
often be removed completely with the use of very little water. A 
similar method of removing the wings from pine seeds is to moisten 
them slightly and then churn the mass in a ees drum until the 
wings become detached. 
Wet and dry process—Whenever the wet process is used, the seed 
must be dried immediately so that its vitality will not be impaired. 
The relative merits of the dry and wet processes depend partly upon 
whether the seed is to be stored for some time or used within a few 
months. In the latter case the wet process is ordinarily safe. If 
the seeds are to be stored for a year or more the dry process should 
be used. 
By churns.—Another method of removing wings is to rub the seeds 
together with a number of small wooden blocks. This may be done 
by churning the seeds and wooden blocks in a box or barrel mounted 
on an axle so as to be rotated, or by keeping the box stationary and 
applying friction by rotating brooms nailed to a spindle running 
through the center. In the latter case, if the box is tilted at a slight 
angle and a hole cut in the lower end, the seeds will gradually work 
out with the wings broken off. 
By screens.—Still other methods depend wholly on the use of 
screens. The simplest of these is to rub the seed as it comes from 
the extractor over a fine screen fastened on an empty box or stout 
frame. The rubbing may be done with a stiff scrubbing brush, a 
block of wood covered with corrugated rubber, or a piece of tough 
carpet, or the hands covered with rough gloves. As the wings are 
rubbed off the seeds gradually drop through the screen, leaving a 
large part of the wings and all of the coarser impurities on top. 
One-sixth inch mesh is the best size for screening yellow pine and 
Douglas fir seed; with lodgepole pine and Engelmann spruce one- 
eighth inch mesh is preferable. The wings of the seed are more 
easily removed if the seeds are moistened slightly with cold water 
before screening. 
With most species the first screening ordinarily does not remove the 
wings completely. To secure this final removal the seeds and small 
chaff coming through the first screen may be churned in a small cyl- 
indrical eae covered with very fine-meshed wire, together with 
several small pieces of wood. This process removes the remainder of 
the wings, which, with other small particles of dirt, fall through the 
screening, leaving clean seed behind. 
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