8 Nebraska Agricultural Exp. Station, Research Bui. 1 1 
the large seed, all three grades of seed — large, small, and un- 
selected — ^yield equally. 
(4) When distinct grades of light and heavy seeds (or large 
and small) are obtained from a fanning mill and planted in equal 
volumes as with a drill set at a uniform rate, slightly smaller 
yields are apt to result from the light seed. The difference in 
favor of large or heavy seed as compared with the original un- 
selected seed is very slight, and probably so small as to have 
little practical significance. 
The conclusion would seem justified that the practical use of 
the fanning mill in seed preparation consists largely in the removal 
of weed seeds and trash when present. If the seed is well cleaned 
at the threshing machine, little further is to be gained by fanning 
mill grading. 
(5) Competition between plants from large and small seeds 
sown in a mixture acts to increase the relative yield from the 
large seeds. This suggests a natural elimination (within a mass 
variety) of poorly adapted types which produce unduly small or 
light weight seed. 
