EXTRACTING AND CLEANING FOREST TREE SEED. 21 



By mechanical cleaners. A somewhat similar method, preferable 

 when the work is done on a large scale, makes use of a mechanical 

 cleaner or wing crusher. This consists of a rotating cylinder bear- 

 ing upon the outside several scrubbing brushes with stiff bristles, 

 which during about one-third of each revolution press firmly against 

 a wire screen of fine mesh. The screen against which the brushes 

 press as they revolve may be adjusted to regulate the pressure of the 

 bristles against it. The seed is dropped into the space between the 

 screen and the brushes, and the wings are removed as the seeds pass 

 under the brushes; the fragments of wings and chaff drop through 

 the wire screen. When using such an apparatus with pine seed a 

 slight moistening of the seeds with cold water is advisable before 

 putting them into the hopper. 



FINAL CLEANING OF SEED. 



The final cleaning of seed is done by screening and fanning. 

 Thoroughly clean seed can not be obtained without fanning. Where 

 no fanning mill is available, fairly clean seed can be obtained by 

 passing the seeds through wire screens of different sized mesh to 

 remove first the coarser particles, such as pieces of cone scales, twigs, 

 and needles, and then the finer chaff and pieces of broken wings; 

 and finally by winnowing the remaining seed in the wind or by 

 bellows or other mechanical devices. A blacksmith's rotary blower 

 has been used effectively in winnowing lodgepole pine seed. 



Seed may be fanned in one of the ordinary farm machines for 

 cleaning grain. It removes practically all broken and empty seed 

 as well as much of the resin and other impurities if the draft is 

 properly regulated and screens with the right-sized mesh are used. 

 It is essential that the wings be removed from seed before fanning, 

 otherwise many good winged seeds will be lost. Not infrequently, 

 particularly with poorly adjusted machines, the seed must be fanned 

 more than once before it is thoroughly cleaned. 



Before purchasing grain-cleaning machines their adaptation to 

 cleaning coniferous seed must be fully determined. Many of the 

 ordinary machines have yielded but poorly cleaned seed with low 

 fertility, even after running the seed through the mill six or seven 

 times. This increases cost of power and labor and adds the expense 

 of storing and handling a considerable amount of refuse with the 

 seed. Two machines have proved satisfactory. One of the impor- 

 tant points in selecting a fanning machine is to secure screens prop- 

 erly perforated for the species which is to be handled. 



Certain impurities, such as pieces of cone scales, resin particles, 

 and twigs of the same size and weight as seeds, can not be removed 

 ordinarily by screening or fanning. The only way to get rid of these 

 is to pick them out by hand, and this is seldom warranted. Such 



