242 EFFECTS OF EXPOSING GERM-CELLS TO RAYS OF RADIUM 



eration of growth on one side. Evidence warranting this interpre- 

 tation is wanting in the case of the two rosettes first described. 



Asymmetry of the rosettes is not unknown in other species of the 

 evening-primrose without special antecedent treatment,* but its fre- 

 quency in the radium-cuhures, and more especially the subsequent 

 behavior of the asymmetrical plants, and which is lacking in unex- 



Fig. 70. Onagra biennis. Functionally Asymmetrical Rosette from a Seed 

 whose Ovary was exposed for 53 Hours after Pollination to Rays from Radium of 

 10,000 Activity in a sealed Glass Tube. The Cauline Stem is beginning to grow 

 horizontally, leaning toward the narrower Portion of the Rosette. 



posed specimens, seems to justify the inference that, in these in- 

 stances the asymmetry is a result of the exposure to the radium rays. 

 This subsequent behavior is illustrated in figure 70, which is a 



* MacDougal,* figure 13. A hybrid between O. Lamarckiana and O. biennis. 



