252 EFFECTS OF EXPOSING GERM-CELLS TO RAYS OF RADIUM 



logical asymmetry, more perfectly accomplished than in the earlier 

 mentioned case, and participated in, not by the leaves alone, but by 

 the entire shoot. In the former instance the entire main axis of the 

 plant is presumably physiologically double, though structurally one, 

 but in the latter plant the difference is expressed in the splitting up 

 of the entire shoot-system into two main axes, each with its own 

 secondary branches and characteristic foliage. 



Fig. 73. Ouagra biennis. Radium Culture, No. I5«, showing two distinct Shoots, 

 morphologicallj unlike, on one Root. Cf. figure 77, and plates 13 and 14. 



As with the earlier described plant, this one may be interpreted 

 as a kind of bud-sport, but calling it a bud-sport does not explain it. 

 Bud-sporting in pedigreed plants is not unknown, and has been 

 described for pedigreed evening-primroses by MacDougal,^ who says 

 that a possible hybrid ancestry is indicated by the bud-sporting of 



