no ILLINOIS STATE ACADEMY OF SCIENCE 



are the progeny of the heaviest mother-beans, but that in a 

 pure line this is not necessarily true. DeVries (5), on the 

 other hand, thinks that the size and the weight of seed are 

 primarily the result of nutrition, in the broad sense, rather 

 than the result of inheritance. 



In so far as specific gravity is concerned, another series 

 of experiments has been carried on. Haberlandt, F. (6) 

 found in working with wheat, oats, etc., that the denser 

 grains yielded the heavier returns in grain, and that the 

 less dense ones yielded the greater amount of straw. 

 According to Wollny, E. (17) the absolute weight and not 

 the specific gravity is the only true index of the value of the 

 grain. Clark, V. A. (2) found that, except in the case of 

 oil bearing seeds, the larger number of good seeds is near 

 the upper limit of the specific gravity for the variety. He 

 concludes, however, that specific gravity is of less import- 

 ance than size in seed selection. 



While each of these fields has been investigated by many 

 workers, a few have considered the combined effect of size 

 and of specific gravity in seed collection. Among the latter 

 is Sanborn (16). He sorted wheat according to size and 

 then separated the large grain into two groups by the use of 

 a brine solution. The yield from his lighter grain surpassed 

 that from his heavy grain. Degrully, L. (3) in working 

 with corn, discarded all the very small and poorly formed 

 grains. He then separated out the lightest one fourth by 

 means of a sodium nitrate solution. He states that the dif- 

 ference of the results in favor of the heavy grain was re- 

 markable. 



Practically all experiments have been carried on under 

 field conditions. They have had for their chief aim the in- 

 fluence of specific gravity and of size of seed on crop pro- 

 duction. A few tests have been made by Kiesselbach and 

 Helm (10) to find the relation of the "sprout value" to the 

 yield of small grain crops. The term "sprout value" is de- 

 fined by the authors as, "The moisture-free weight of the 

 maximum plant growth derived from the seed when planted 

 and grown in a non-nutritive quartz medium and in absolute 

 darkness." 



