effects of exposing seeds io5 



Experiment 23 

 Januar}^ 11, 9 A. M. 



Eight seeds of white ijiustard {Brassica alba), soaked in water 

 for 15 hrs., were placed in Zurich germinators in the dark-room with 

 the glass tube of RaBrg (5 mg., 1,500,000 x) resting on the seeds, 

 the radium evenly distributed along the bottom of the tube. 



Control of 8 seeds similarly treated and placed under an empty 

 glass tube. 



January 12, 9 A. M. 



One radiated seed has begun to germinate ; two control seeds. 

 The seeds were planted in the same pot of soil, the exposed seeds 

 on one side, the control seeds on the other side of the pot. 



January 14, 9 A. M. 



Of the radiated seeds, two hypocotyls have pierced the soil ; of 

 the control seeds, five. 



January 16, 4 : 30 P. M. 



Radium Control 

 Lengths of hypocotyls of six seed- Lengths of hypocotyls of six seed- 

 lings above soil surface as follows : lings above soil surface as follows : 

 33.50 mm. 30-50 mm. 

 23.00 37'00 

 22.00 14.00 

 18.00 39'00 

 20.00 14.00 

 30.00 38.00 



146.50 mm. 172.50 mm. 



Average, 24.41 mm. Average, 28.75 mm. 



January 17, 3 : 45 P. M. 



One seedling was injured in each culture and discarded. 



Radium Control 



46.00 mm. 49-50 mm. 



36.00 45.50 



35-50 30.00 



41.50 53.00 



38.00 25.00 



27.00 49.00 



224.00 mm. 252.00 mm. 



Average of 6, 37.33 mm. Average of 6, 42.00 mm. 



