EXTRACTING AND CLEANING FOKEST TREE SEED. 15 



temperature the quicker the drying can be accomplished. Dry heat, 

 however, is more effective than moist heat, and heat that is too in- 

 1 ense is very apt to impair the fertility of the seed. This is particu- 

 larly true of intense moist heat. Often this injury to seed is not 

 appreciated at the time, since the deterioration does not become 

 apparent until several months later. 



The maximum temperature which should ordinarily be applied to 

 all species except lodgepole pine is 120 F. This can be raised safely 

 to 130 F. if the air is dry and good ventilation provided. Lodge- 

 pole cones should not as a rule be subjected to a temperature of more 

 than 140 F., although this can be raised safely to 150 F. under 

 favorable conditions. Lodgepole pine cones are hardest to open; 

 then come in order western w r hite pine, western yellow- pine, Engel- 

 mann spruce, and finally Douglas fir, which can often be dried satis- 

 factorily at a temperature of 110 F. 



TIME REQUIRED. 



At well-equipped plants lodgepole pine cones should be thoroughly 

 dried at a constant temperature of 140 F. in from 8 to 10 hours, and 

 other species at a constant temperature of 120 F. in 10 to 15 hours, 

 assuming that the cones are mature and moderately dry when put 

 into the kiln and that the room is evenly heated and well ventilated. 

 Under less favorable conditions these periods may be greatly in- 

 creased. In one instance, lodgepole pine cones dried in a tent at 

 140 F. took 44 hours to open. The difference was due mainly to 

 loss of heat in the tent and its uneven distribution. Preliminary 

 drying of the cones for a few hours at 80 to 100 F. has been found 

 an advantage. Opening will also be hastened if the cones are spread 

 thinly in the trays and stirred frequently, to make the drying more 

 uniform. 



EXTRACTING SEED FROM DRIED CONES. 



After the cones have been thoroughly dried, the next step is to 

 extract the seed. Merely to rake over the cones as they are drying 

 in the sun or kiln is the simplest but least efficient method. It is 

 most successful with western yellow pine, but even with this species 

 better results can usually be obtained by shaking. The practice of 

 placing cones in sacks and beating them with clubs to loosen the seed 

 has also proved unsatisfactory. It requires too much time and yields 

 only a little additional seed, which is apt to be of poor quality. 



TRAY SHAKERS. 



In nearly every case, therefore, to secure the maximum amount of 

 seed some method of shaking must be used to release the seeds from 

 the opened cones. One of the earliest and simplest devices is a tray 



