A. C. REDFIELD AND E. M. BRIGHT 

 .;5 / 



299 



The seeds were exposed to the \i .id 7-rays of radium by placing 

 them in the dry condition in a r t-tube, closely packed about a 

 glass tube containing radium emanatfon.^ The a-rays failed to pene- 

 trate the walls of the tube; in comparison to the j8-rays, the 7-rays 

 doubtless contributed to the effect in neghgible degree owing to their 

 limited absorption in the seed. 2 days after radiation the seeds were 

 moistened and the CO2 production was determined. They were then 

 given an opportunity to germinate and grow. In each experiment 

 an equal nunlber of unradiated seeds was kept as a control. Their 

 CO2 production was measured and they were then set to germinate 

 on the same moist filter paper and under the same cover with the 

 radiated seeds. 



TABLE II. 

 Comparison between Radiated and Unradiated Seeds. 



* Method of calculating explained in text. 



Table II, containing the results of six experiments, shows that the 

 difference in the rate of CO2 production between radiated and unradi- 

 ated seeds is greater in almost every case than that found between 

 comparable lots of unradiated seeds, and that the rate ofCOi production 

 in radiated seeds is invariably greater than in the corresponding unradi- 

 ated control. In comparison to this it is seen that the germination 

 of the radiated seeds is retarded to a marked degree. A notable 

 feature is that the radiated seeds germinate much more slowly than 

 normal for it usually requires 2 days before any of these seeds send out 

 roots, and the number of seeds which have done so increases from day 



' We are indebted to Dr. William Duane for placing a supply of radium belong- 

 ing to the Cancer Commission of Harvard University at our disposal. 



