EFFECTS OF EXPOSING GERM-CELLS TO RAYS OF RADIUM 25 1 



half, in general appearance and behavior, was similar to the narrow- 

 leaved form described above, and illustrated in plate 8. This 

 plant, in light of its method of treatment, offers evidence, in addition 

 to what we already possess, that mutation is not confined to the period 

 during and after fertilization, but that it may occur, or at least be 

 initiated previous to fertilization, and in either the male or the female 

 gamete. Taxonomic descriptions of the two halves of this plant 

 (i5« broad and 15a narrow of my cultures) are appended. 



15a broad 

 Rosette leaves finely and sparingly 

 pubescent, the larger ones about 15 

 cm. long; blades spatulate to ellip- 

 tic-spatulate, sinuate-dentate espe- 

 cially below the middle, often sharply 

 or prominently so near the base, 

 much longer than the petioles ; stem 

 7 dm. tall, with elongate ascending 

 branches on the lower part; stem- 

 leaves mostly spreading ; blades nar- 

 rowly elliptic, somewhat acuminate 

 at the apex, sinuate-dentate ; bracts 

 similar to the stem-leaves but smaller 

 and usually broadest below the mid- 

 dle; hypanthium about 35 mm. 

 long; sepals about 25 mm. long, 

 slightly shorter than the free portion 

 of the hypanthium, the free tips in 

 the bud subulate, 2.5-3.5 ^'^^^' loiig ; 

 petals about 15 mm. long, nearly 

 truncate at the apex ; capsules colum- 

 nar, slightly narrowed to the apex, 

 about 35 mm. long, much nari-ower 

 than the bracts. 



A functional difference between the two halves is shown by the 

 fact that after the broad-leaved half was entirely through flowering, 

 the narrow-leaved portion still bore opening buds and flowers. The 

 equivilancy of the two shoots was ultimately obscured by the more 

 vigorous and rapid development of the broad-leaved half. 



Let us briefly consider this plant in light of the morphologically 

 asymmetrical plant described on page 243. Here is also morpho- 



15^! narrow 

 Rosette leaves finely and sparingly 

 pubescent, the larger ones 10-12 cm. 

 long; blades almost linear, acumi- 

 nate at both ends, undulate, some- 

 what longer than the petioles ; stem 

 6.5 dm. tall, with relatively short 

 ascending branches throughout ; 

 stem-leaves mostly di'ooping ; blades 

 narrowly linear-lanceolate to almost 

 linear, tapering to both ends, undu- 

 late-sinuate ; bracts similar to the 

 stem-leaves but smaller; hypanthium 

 about 45 mm. long; sepals about 30 

 mm. long, fully as long as the free 

 portion of the hypanthium, the free 

 tips in the bud long-subulate, 3-4 

 mm. long; petals about 20 mm. 

 long, nearly truncate at the apex ; 

 capsules almost columnar, about 25 

 mm. long, slightly narrower than the 

 bracts. 



