EXTRACTING AND CLEANING FOREST TREE SEED. 19 



The amount of broken cone scales depends partly on the species 

 and partly on the treatment to which the cones are subjected during 

 extraction. Seed of species whose cones are very brittle naturally 

 contains more extraneous matter of this character. With most spe- 

 cies, however, it is possible to avoid breaking the cones badly if they 

 are shaken out rather than crushed out. The common method of 

 putting heavy blocks of wood in the shaker with the cones is excellent 

 for species whose seed is hard to extract or w r hose cones are tough. 

 For other species, however, this method is undesirable, since it not 

 only increases the difficulty of cleaning the seed, but is apt to injure 

 it. It is advisable, therefore, to use no more violence than necessary, 

 even if this makes extraction slower. The loss of time will be more 

 than offset by the greater ease of cleaning. Twigs and broken needles 

 can be largely kept out by screening the cones before drying is begun. 



The presence of broken seeds depends chiefly on the treatment of 

 the cones, which has been discussed. Empty seeds are also present 

 in nearly all samples. Their proportion depends partly on the 

 species, but mainly on the season. In a poor seed year empty seeds 

 are usually abundant; in a good seed year comparatively rare. They 

 can be separated from good seed only by fanning. 



The presence of resin in seed depends mainly upon the species. It 

 is probable, however, that crushing or overheating the cones increases 

 its amount. It is certain that overheating, by softening and melting 

 the resin, makes it much harder to remove. When the cones are 

 heated to such an extent that resin sticks to the seed, it is practically 

 impossible to remove it. Dust is always present to a greater or less 

 extent. 



REMOVAL OF WINGS. 



The seed of all western conifers commonly handled have wings, 

 which are usually, though not necessarily, removed when the seed 

 is cleaned. Removal of the wings probably decreases the germinative 

 power of seeds to a small extent. It so greatly facilitates the ease 

 with which they can be handled, however, that the practice is almost 

 universal. In the pines, the entire wing may be detached from the 

 seed with comparative ease, particularly if the seeds are first mois- 

 tened slightly. With other species, however, the wings form part of 

 the seed coat, and can be removed only by actually breaking them 

 off. Moistening the seed is therefore of doubtful value. 



By flails. One of the oldest and commonest methods of removing 

 wings is to work the seed over in seamless sacks, the mouths of which 

 are securely tied. The sacks are beaten with light flails, usually of 

 leather, or kneaded with the hands and knees. Sometimes the sacks 

 are tramped under foot for a few moments, but this method impairs 

 the quality of the seed. With the pines, to which this method is 

 particularly applicable, the wings are more readily removed if the 



