112 



EFFECTS OF EXPOSING SEEDS 



the same period of time to rays from radium of different strengths of 

 activity. 



May 4, 10 A. M. 



Four sets of four seeds each of Zea Mays were exposed for 16 

 hours to radioactive preparations as follows : 



Set A to RaBrg, 1,800,000 x » in sealed glass tube. 



Set B to RaBrg, 1,500,000 x , in sealed glass tube. 



Set C to RaBr2, 10,000 x , in sealed glass tube. 



Set D to radio-tellurium in sealed glass tube. 



Set E, Control — not exposed. 



Similar exposures were made for 24 hours and for 33 hours, and 

 the seeds were then planted in soil. 



Exposure for 16 Hours 

 May 10, 10 A. M. 



The heights of the seedlings above the surface of the soil are as 

 follows : 



