effects of radioactive air on growth i5i 



Experiment 43 

 Repetition of Experiment 42, only with the air and emanation 

 delivered at a distance of 190 mm. above the seeds, planted on the 

 surface of the soil. 



June I, 4 : 30 P. M. 



Dry seeds of timothy grass were sown evenly over a blotter, kept 

 moist by being placed on damp cotton, and placed under the bell-jar 

 into which the radium emanation is to be drawn. The opening of 

 the funnel through which the emanation is to be delivered is about 

 190 mm. from the surface of the blotter where the seeds lie. 



Control with no radium. 



June 3, 6 P. M. 



No seeds have germinated in either culture. 



June 4, 12 M. 



In the exposed culture only one or two seeds have begun to 

 germinate. 



Fig. 32. Experiment 43. Retardation of Germination and Growth of Timothy 

 Grass by exposure to Air containing the Emanation of Radium. 



In the control culture the seeds have quite generally germinated, 

 with plumules estimated at from i to 2 mm. long. 



June 5, 12 M. 



The seedlings in the control culture are about 5 mm. high, with 

 the green color well developed. Growth is uniform throughout the 

 culture. 



The exposed seedlings are not more than one half as tall as the 

 control, and only very slightly green. Growth seems uniform 

 throughout the culture. 



June 8, 3 130 P. M. 



After seven days of exposure the radiated seedlings are still 



