EFFECTS OF EXPOSING SEEDS I33 



A time-interval of from three to six days between exposure and 

 planting makes only a very slight, if any difference, at first, and any 

 early difference, if one really exists, does not persist. 



Experiment 31 



Object : To ascertain the result of varying the distance between 

 the radium-tube and the seeds, on the effect of radium ravs on the 

 germination and growth of Lu^imis albus. 



Four sets of six seeds each of L. albus were exposed for 72 hours 

 to the rays from the same amount of radium bromide of 1,500,000 

 activity, contained in a sealed glass tube. The distances from the 

 bottom of the radium-tube to the upper surfaces of the seeds were 

 respectively 80 mm., 40 mm., 20 mm., and o mm. 



December 7, 10 A. M. 



The seeds, exposed as above, together with a control (unexposed) 

 set of six, were all planted without soaking, in soil in pots. 



