136 



EFFECTS OF RADIUM RAYS IN THE SOIL 



March 10, 2 P. M. 



After an exposure of 106 hours, the seedlings in the pot contain- 

 ing the radium are all up, and are most decidedly taller than those 

 in the control culture, 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 average 50 

 mm., those in the middle circle 46 mm., and those in the inner circle 

 42 mm. taller than those in the corresponding circle of the control. 



Fig. 25. Experiment 32. The Former Control ( C) is now Exposed to the Radium 

 (C/?), and the Culture Formerly Exposed (i?) becomes the Control. The Tube in 

 CR now Contains the Radium, while the Tube in/? is now the Empty Tube. Cf. 



FIGURE 24 . 



After the plants were photographed (figure 24), one seedling 

 was carefully removed from each culture, and the soil washed from 

 its roots. The plant from the exposed culture has root-hairs from 2» 

 to 3 times as long as those on the control, and they are also more 

 numerous. 



