No. 504] PHYSIOLOGICAL EFFECTS OF BADIUM BAYS 767 



the sealed glass tube of radium (1,500,000 X) was in- 

 serted vertically into the soil, with the end containing the 

 radium at a depth of about 5 mm. below the surface. 

 A control culture was similarly arranged with an empty 

 glass tube. After an exposure of 106 hours the seed- 

 lings in the pot containing the radium were all up, and 

 were most decidedly taller than those in the control cul- 

 ture, three of which were not yet up, and all of which 

 were less developed in every way than those exposed to 

 the radium. 



The plants in the outer circle of the exposed culture 

 averaged 50 mm., those in the middle circle 46 mm. and 

 those in the inner circle 42 mm. taller than those in the 

 corresponding circles of the control (Fig. 4). 



On the sixth day after planting the radium tube was 

 changed to the control culture, and the empty tube re- 

 placed the radium. The pot C was then irradiated (CR) 



