CHAPTER XII 



EFFECTS OF RADIUM RAYS ON THE SYNTHESIS 

 OF CARBOHYDRATES 



I. Effect on Photosynthesis 

 A few experiments were made to test the effects of radium rays 

 on the photosynthetic activity of the green cell. These experiments 

 are qualitative, and in many respects extremely crude. It is hoped, 

 however, that they may serve to blaze the way for more accurate 

 quantitative work. 



Experiment 67 

 Object : To ascertain the effect of the rays from rods coated with 

 Lieber's "radium coating" on photosynthesis in the bean leaf 

 {Phaseolus). 



June 9, 10 130 A. M. 



A coated rod (25,000 x ) was placed horizontally about three mm. 

 above a mature green leaflet of a bean plant, growing in a north 

 window. 



A rod of 10,000 activity was similarly placed over a leaflet of an 

 adjacent plant. 



Other leaves on the same plants served as controls, and a portion 

 of the exposed leaf from each plant was tested and found to contain 

 starch at the beginning of the experiment. 



June 9, 5 P. M. 



Nyctitropic movement has lowered both leaves away from the 

 rods, and beyond their influence. 



June 10, 10 A. M. 



The rods were readjusted to their former positions. 



June 10, 2 : 30 P. M. 



The leaves were excised, dechlorophyllized, and tested with 

 iodine for starch. 



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