DEVELOPMENT OF VEGETATIVE AND FLORAL BUDS 269 



State with Buvat (1952, 1955) that the central zone, which has 

 become active mitotically, is responsible for the formation of the 

 bracts, branches of the inflorescence, and the resuhing flowers. Rather, 

 mitotic activity appears to begin in that group of cells just beneath the 

 central zone or just distal to the pith rib meristem, and ultimately 

 involves the whole apex which becomes transformed into a condensed 

 stem tip or short shoot. Certainly the peripheral meristem continues 

 to be the active peripheral region which gives rise to appendages, both 

 bracts and axillary buds; these early appear spaced on the axis of the 

 inflorescence. 



Papaver somniferum is a long-day plant. Whereas Xanthium, when 

 flowering, produces a head and Chenopodiiim illustrates a branching 

 inflorescence, Papaver has the whole axis closed by a single flower 

 (Fig. 6). The transition to flowering is little different from that in 

 Xanthium or Chenopodiiim. The central zone, like that in Chenopo- 

 diiim, is a kind of cone, somewhat V-shaped in section; it can be 

 recognized in Fig. 5 as about 8 cells in diameter in the tunica region. 

 This'central zone has entirely disappeared before or concomitant with 

 the development of the single flower. 



Although this investigation has included the changes in the apical 

 region accompanying flowering in the soy bean. Glycine max, a short- 

 day plant, and in the annual form of Hyoscyamiis niger, a much 

 studied long-day plant, we need only state in this brief account that 

 little more information was added by including these two species. The 

 story of either of these apices as modified in flowering is essentially 

 the story for the other, and neither is fundamentally different from 

 that of Chenopodiiim, except as related to individual differences in 

 development of inflorescences. 



DISCUSSION 



To the authors, it seems impossible to follow Gregoire (1938) in 

 the belief that irreducible differences exist between the vegetative and 

 the flowering apex. Philipson in a series of papers, ending in two sum- 

 maries (1947, 1949), points out (1949) that "the constitutional 

 tendency of the vegetative apex is to produce growth in length of an 

 axis; that of the reproductive axis is to produce a meristematic surface 



