394 



Plant Physiology 



ences at maturity between the product of heavy and light 

 seed are intensified when the conditions are unfavorable. 

 With all conditions favorable, differences at first evident 

 might, in time, disappear. In all cases, comparisons are 

 only fair within the variety. 



Hicks and Dabney have made a test of the relative 

 effects of weight upon vigor, using many sorts of seeds. 

 They attempted to eliminate all unsound seed, conse- 

 quently the material was sieved and afterwards hand 

 selected. The results are as follows : - 



EXPERIMENTS WITH HEAVY AND LIGHT SEEDS 



1 A, heavy; B, lighter than A; C, lighter than B. 



