i68 



EXPOSED WATER AND FRESHLY FALLEN RAIN 



The less rapid growth in the water in which the radium-tubes were 

 immersed is shown graphically in another figure. The curve for 

 the results of exposure to the radium of 10,000 activity is omitted 

 for the sake of clearness. 



Fig. 37. Experiment 51. Acceleration of Growth of Ltipintis albtis by watering, 

 after planting in Soil, with Water exposed to Radium Rays. Cf . figure 38. 



Experiment 51 



Object : To ascertain the effect on germination and growth of 

 watering with water in which a sealed glass tube of radium bromide 

 has been immersed. 



June 29, 9 : 30 A. M. 



Into each of two pots of soil, thoroughly moist with tap-water, were 

 planted four seeds of Lupintis albus, and into each of two other 

 similar pots four seeds of Zea Mays. 



June 30, 9 : 30 A. M. 



One pot of each set was watered with 100 c.c. of tap-water, in 

 which a glass tube containing 10 mg. of RaBr2 of 1,800,000 ac- 

 tivity had been immersed for 8 days. The other pot in each set was 

 watered with a like amount of ordinary, unexposed tap-water. 



This method of watering was continued daily until July 25, the 



radium tube being in the water from i to 9 days before each watering. 



Observations of germination and growth were recorded as follows : 



