EFFECTS OF EXPOSING SEEDS 



121 



The experiment suggests that the degree of activity of the radium 

 is a more important factor than the duration of the exposure. That 

 is, that a slight increase in activity is more effective than a relatively 

 slight increase in the duration of the exposure. If this is so, the facts 

 concerning the effect of varying the length of exposure will be more 

 readily ascertained by exposing for longer periods of time. With this 

 in view the following experiment was made, and the greatest care 

 was exercised in choosing seeds apparently as nearly alike as pos- 

 sible in size and vigor, in distributing the radium salt evenly over the 



120 



10 



11 



12 13 



Day of month 



Fig. i8. Effect on the Growth of Zea Mays of Various Durations of Exposure of 

 the Grains, before Planting, to Radio-Tellurium in a Sealed Glass Tube. 



bottom of the horizontal tube, in having the tube in contact with all 

 the seeds, and at the same region of the seed, and in having the pots 

 in which the exposed seeds were planted, and all other conditions of 

 growth as nearly uniform as possible for all four cultures. 



Experiment 27 

 Object : To ascertain the effect of varying lengths of exposure to 

 the rays of radium of the same activity on the germination and 

 growth of Lu^inus albus. 



