EFFECTS OF EXPOSING SEEDS 



89 



Experiment 5 



Object : To ascertain the effect of a rays only (from polonium), 

 on the germination and growth of wheat. 



Sixteen grains of wheat {Triticiim vulgar e^ Henderson's "Well- 

 man Fife ") were exposed to « rays by being placed in contact with 

 a metallic rod coated with polonium. 



June 7, 9 :30 A. M. 



After 10 days' exposure the exposed grains and 16 unexposed 

 grains were planted in soil. 



The heights of the seedlings above the surface of the soil were 

 measured as follows : 



While at first there was no significant difference in the heights of 

 the exposed and the control seedlings, the exposed plants later grew 

 much more rapidly than the control. See figures 4 and 5. 



Summary 

 From the above experiments it is seen that both germination and 

 growth of Lupnus albus, Phaseolus, and Avena saliva are retarded 



