I20 



EFFECTS OF EXPOSING SEEDS 



the plants of this culture grew faster, so that, from this time on, the 

 rate of growth varied inversely as the strength of the radium. In 

 FIGURE II, also, growth following exposure to the larger amount of 

 the weaker radium is shown to be less at first than after exposure to 

 the radium of 1,800,000 x , but soon becomes greater, though the 

 indicated effect of the radium of 1,500,000 x is less than that of 

 either the 10,000 x or the 1,800,000 x radium. 



10 



14 



15 



Fig. 17. 



11 12 13 



Day of month 



Effect on the Growth of Zea A/ays of Various Durations of Exposure of 

 the Grains, before Planting, to Radium Rays. Activity, 1,800,000. 



If we consider the effect of rays of the same strength allowed to 

 act for varying lengths of time (figures 13, 16, 17), we shall not find, 

 in this experiment, that the hypothesis is very well verified. With the 

 radium of 10,000 x (figure 13) the results are what the hypothesis 

 calls for.* 



*The 10,000 X culture of 33 hrs. exposure went bad, and was discarded, but this 

 is only partially true in the other three cases (figures i6, 17). These results being 

 at variance with the expectation warranted by previous experience, it was impossible 

 to avoid the conclusion that some unknown source of error crept into the experiment. 

 I think it best, however, to give the results as they were obtained. 



