EXTRACTING AND CLEANING FOREST TREE SEED. 9 



the sheet successively and throwing the cones toward the center. 

 One corner of the canvas is then thrown over, nearly covering the 

 cones; next, the corners to the left and right of the first are folded 

 over; and finally the remaining corner, opposite the first, is drawn 

 over all and tucked under the farther edge of the pile. The four 

 thicknesses of canvas help to retain the heat absorbed by the cones 

 during the day and furnish good protection from rain. As an addi- 

 tional precaution the canvas folds may be weighted with rocks and 

 an extra sheet thrown over the pile. A sheet more than 14 feet 

 square is not easily handled by one man. 



When cones are dried on platforms or in trays protection must be 

 afforded by covering with sheets of canvas, which should be large 

 enough to overhang the racks and protect the seed in the lower tray. 

 With cones spread directly upon the ground, the use of cover sheets 

 requires less time and labor in respreading the cones, but makes many 

 more sheets necessary. 



Covering cones at night protects them from nocturnal rodents, as 

 well as from dampness. It is usually necessary, however, where 

 rodents are abundant, to protect the drying areas by poisoned grain. 

 Birds may often be frightened off by cloth streamers on small stakes, 

 or wires, around the sheets. When racks are used for drying, squir- 

 rels may be kept out by tacking sheets of tin sloping downward on 

 each leg of the frame. Care must also be exercised to prevent seeds 

 which have fallen from dried cones from being blown away by high 

 winds. This is best done by catching the seeds in a canvas-bottomed 

 tray with 4-inch sides. 



Space required. The space required for spreading cones varies so 

 much with different species, and even with the same species in dif- 

 ferent localities, that it is hard to give specific definite figures. The 

 following table indicates the average number of square feet of drying 

 surface per bushel for each of the four species most commonly col- 

 lected, as well as the capacity of a 12 -by 14 foot canvas sheet. This 

 applies to green cones spread thinly. As they dry their volume will 

 expand at least 50 per cent, bringing the cones into closer contact and 

 making more frequent raking necessary. 



For yellow pine and Douglas fir, the two chief species handled, 16 

 square feet per bushel 'will usually be needed, making it possible to 

 spread 10.5 bushels on each 12 by 14 foot drying sheet. To allow 

 r,s241 Cir. 20812 2 



