EFFECTS ON PLANT RESPIRATION 



199 



The greater acceleration following exposure to the radium of 

 weaker activity may possibly be attributed to the fact that there was 

 much more of the latter salt in the glass tube than of the former, the 

 amounts being for the 10,000 x .52 gm., for the 1,500,000 x 10 mg. 

 (figure 50). 



Experiment 79 



The following experiment was arranged as in No. 77, using only 

 the radium of 1,500,000 activity. Readings of the height of the 

 mercury column in the graduated glass tube were taken as follows. 

 The scale divisions are multiplied by 10. 



Here also acceleration of respiration has followed exposure to the 

 rays from radium of 1,500,000 activity. (See figures 51 and 52.) 



Experiment 80 

 In order to ascertain the effect, on the respiration of germinating 

 wheat grains, of a previous exposure, in the dry condition, to the 



