154 effects of radioactive air on growth 



Experiment 46 

 Repetition of Experiment 45. ' 



The experiment was arranged as described in Experiment 45. 

 Measurements of growth in length were made as follows : 



Growth in the atmosphere containing the emanation is more rapid 

 than the normal growth. 



In a fourth repetition of this experiment the 5 exposed seedlings 

 averaged 9.60 mm. growth in 20 hours, while the average growth of 

 the control seedlings was only 7.30 mm. Again the average amount 

 of growth in 24 hours was, for those exposed, 18.41 mm. ; for the 

 control, 15.80 mm. 



In a fourth repetition of Experiment 45, the following measure- 

 ments were made : 



