io8 



EFFECTS OF EXPOSING SEEDS 



Fig. 8. Experiment 2-^. Retardation of Germination and Growth of Oats Exposed to 

 Radium Rajs During Early Stages of Germination. Cf. figures 9 and 24. 



April I, 3 P. M. 



After removing the plants and carefully washing the soil from 

 the roots, the following observations were made : 



Roots 

 Number. 



Length. 



Secondary 

 roots. 



Diameter.] 



Root-hairs. 



Root-tips. 



Radium 

 3.5 (av. for 10 plants). 



Control 

 5.7 (av. for 7 plants). 



Average (estimated) about Estimated twice the length of 

 ]/2 as long as the control. the radiated. 



None, except a few very Numerous on all plants save 

 short ones on the most vig- one, which had only 3-3 small 

 orous plant. ones. 



Decidedly club-shaped in 

 five of the specimens. 



Appear to be slightly more 

 numerous, and about twice as 

 long as in the control plants. 

 (See R, FIGURE 9.) 



Much darker colored than in Of normal appearance. De- 

 the control plants, cidedly lighter than those of the 



radiated plants. 



Normal appearance : not en- 

 larged near the root-tip. 



Normal. 



