20 EXTRACTING AND CLEANING FOREST TREE SEED. 



seed is slightly moistened with cold water. This ma}- 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 cylindrical 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 drum, 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. 



