244 EFFECTS OF EXPOSING GERM-CELLS TO RAYS OF RADIUM 



The morphological asymmetry was not confined to the rosette 

 stage, but persisted throughout the entire life of the plant, giving 

 narrow leaves on one side of the narrow upright stem, and on the 

 secondary branches growing in their axils, and broad leaves on the 

 opposite side and branches (plate 7, a different plant than figure 71). 



Fig. 71. Onagt-a biennis. Morphological Asymmetr}'. From a Seed developed 



in an unexposed Ovary whose Stigma was pollinated with Pollen exposed for 24 



Hours to Rajs from Radium of 1,500,000 Activity in a sealed Glass Tube. Cf. 

 PLATE 7. 



The difficulty of explanation is greater here than in the former 

 case. The rosette (figure 71), bearing leaves of both kinds sug- 

 gests that a fertilized egg may have been unequally influenced by 

 the radium rays, but such a condition is excluded by the fact that 

 only the pollen was exposed. An untreated ovary was pollinated 

 with pollen that had been exposed for 24 hours to the rays from 

 radium bromide of 1,500,000 activity. There seem to exist in the 

 germ-cells of this species two factors expressed in the mature organ- 

 ism by a different ratio between the length and breadth of the leaves. 

 Most frequently the broad-leaved type appears, while at times, under 

 some unrecognized environmental stimulus, the narrow-leaved form 

 results. The radium rays may affect this unit-character in either 

 germ-cell, and, when we recall that, after fertilization, the male and 

 female chromatins do not fuse until synapsis immediately preceding 



