CHAPTER VII 



EFFECTS ON GROWTH OF EXPOSING SEEDS TO 

 RADIUM RAYS 



I. Effects on Growth of Exposure of Unsoaked Seeds 

 The object of the following experiments was to ascertain the 

 effect on germination and growth of exposing unsoaked seeds to the 

 rays of radium. 



Experiment i 

 January 28, 5 : 15 P. M. 



Six seeds of Lupinus albtis, unsoaked, were placed under the 

 radium tube (10 mg., 1,500,000 x), with the tube resting on the 

 hilum edges of the seeds. Six control seeds were similarly placed 

 under an empty glass tube. 



February 2, 4 P. M. 



After five days radiation the seeds were planted in soil in separate 

 pots, and transferred to the propagating-house. 



February 9, 9 A. M. 



Radiufn Control 



The cotyledons of five seeds are The cotyledons of three seeds are 



just emerging; the sixth is just arch- raised about 5 mm. above the surface 



ing the soil. of the soil, the cotyledons of two seeds 



have just emerged, and the cotyledon 

 of one seed is just breaking the soil. 



February 11,3 130 P. M. 



Only four seedlings have the coty- Five seedlings have the cotyledons 



ledons clear of the soil, one of which entirely clear of the soil, and well 



has the cotyledons spread showing spread apart, showing the plumules. 



the plumule. The cotyledons of the other seedling 



are just emerged. This culture is 

 more vigorous, and further advanced 

 in every way than the radiated one. 



The lengths of the hypocotyls above the surface of the soil are as 

 follows : 



84 



