THE AMERICAN NATURALIST [Vol. XLII 



and 15 hours, these grains, together with twenty similar 

 but unexposed ones, were planted in flower pots in soil. 

 The control grains germinated two days sooner than those 

 exposed, and, at the end of seven days after planting, 

 the seedlings from the exposed grains were just appear- 

 ing above the soil, while the control plants were several 

 centimeters tall (Fig. 3). 



In order to test the effect on germination and growth 

 of radium rays in the soil, 16 unsoaked grains of " Lin- 

 coln " oats were sown in soil in a flower pot, in 3 con- 

 centric circles, at distances of 7 mm., 22 mm. and 

 45 mm. from the center of the pot. At the center 



