122 



EFFECTS OF EXPOSING SEEDS 



October 22, 10 A. M. 



Three sets of six dry seeds each, A, B, and C, were exposed as 

 follows, to the rays from 10 mg. of RaBr^, 1,800,000 activity, in a 

 sealed glass tube : 



A. 72 hrs. Planted 4 days after the end of the exposure. 



B. 50 hrs. " 2 " " " " " " 



C. 26 hrs. " 21 hours " " " " " 



D. Control, not exposed. 



The seeds were then planted without soaking, in separate pots in 

 soil. 



Fig. 19. Expei-iment 27. Effect of Duration of Exposure to Radium Rays on 

 Germination and Growth of Lupinus albus. Length of Exposures, from Left to Right, 

 72 Hours, 50 Hours, 26 Hours, Control. Cf. figure 20. 



The lengths of the hypocotyls above the surface of the soil were 

 measured as follows : 



45.50 mm. 50.00 mm. 



7.58 mm. 10.00 mm. 



Poor seed. Discarded. 



c 



26 hrs. 

 10.00 mm. 

 1 1. 00 

 9.00 

 10.00 

 11.00 

 12.00 



63.00 mm. 

 10.50 mm. 



D 



Control 

 12.00 mm. 

 17.00 

 1 1. 00 

 16.00 

 12.00 

 13.00 



Si .00 mm. 

 13.50 mm, 



