EFFECTS OF EXPOSING SEEDS 



127 



April 26, II A. M. 



14 hrs. 6 hrs. 4 hrs. 3 hrs. 2 hrs. Control 



23.60mm. 25.75 mm. 24.00 mm. 25.62 mm. 26.85 ^^- 23.50 mm. 



At the end of five weeks (May 24) there was no appreciable dif- 

 ference in the six cultures that could be attributed to the radium rays. 

 An exposure of dry lupine seeds for 14 hrs. to radium of 1,500,000 x 

 was not sufficient appreciably to affect germination or growth. 



Experiment 29 



The relation between the degree of activity of the radium and the 

 retardation of growth is clearly shown by the following experiment. 



Object: To ascertain the effect on the germination and growth 

 of Litpinus albus of exposure for the same period of time to rays of 

 radium of different degrees of activity. 



Oct. 30, I : 30 P. M. 



Three sets. A, B, and C, of six dry seeds each of L. albus were 

 exposed to the rays of RaBr2 in sealed glass tubes by laying the tubes 



Fig. 22. Experiment 29. Effect on the Germination and Growth of Ltipinus albus 

 of Exposure for the Same Period of Time to Rays from Radium of Different Activities, 

 as Follows (from Left to Right) : 1,800,000; 1,500,000: 10,000; Control. 



against the hilum-edges of the seeds. The time of exposure was 

 91.50 hrs., and the strengths of the radium as follows : 



A. 1,800,000 X . 



B. 1,500,000 X . 



C. 10,000 X . 



D. Control — not exposed. 



