ii8 



EFFECTS OF EXPOSING SEEDS 



The results of this experiment are rather difficult to interpret, and 

 do not harmonize in some places with the hypothesis that the effect 

 of radium rays on growth varies directly with the activity of the 

 radium, and the duration of the exposure. In the first place, the 

 results of exposure to the various preparations are not in all points 

 strictly comparable. For example, there was 100 times (.52 gm.) 

 as much of the radium bromide of 10,000 x and of radio-tellurium 

 as of the stronger radium preparations. Again, in laying the tubes 

 over the seeds, it is more than probable that the salt was not dis- 

 tributed along the tube precisely similarly in any two cases, and doubt- 



