4 i6 BOTANICAL GAZETTE [December 



end in the terminal lobe of the perianth. At either side as it turns 

 upward this branch is joined by a branch from the perianth 

 bundle itself (fig. 21 x). The presence in the wall of the ovary 

 of 3 distinct bundles lends strong support to the view that the ovary 

 is made up of 3 carpels, although no evidence of separate lobes 

 could be distinguished at the upgrowing margin of the young 



ovary. 



Ovule. — The nucellus of the ovule is initiated by the inward 

 and downward growth, on the side opposite the bract, of the subepi- 

 dermal cells of the wall of the ovary which border on the ovarian 

 cavity (figs. 14, 18). The integuments arise soon after the carpel 

 has closed in above the ovule to form the style and stigma. The 

 inner integument starts as a ringlike outgrowth from the sides 

 of the ovule near its middle. This is due chiefly to the activity 

 of its epidermal cells (fig. 26). Soon after the inner integument 

 appears, a second outgrowth slightly anterior to its base leads to 

 the development of the outer integument (figs. 26 O/n, 28) . These 

 ringlike outgrowths continue growing downward around the 

 ovule, that is, toward the micropyle, as it elongates. By the time 

 the tapetal cell has divided, producing the 4 or 5 layers of cells 

 constituting the tapetum, and the megaspore mother cell has come 

 to occupy a central position within the nucellus, the inner integu- 

 ment has completely closed together above the nucellus to form the 

 micropyle (fig. 28). The inner integument is longer than the outer 

 from the outset of its development. At the time the embryo sac 

 is ripe, the integuments extend considerably beyond the nucellus 

 into the ovarian cavity, and each is 3 cells in thickness. From 

 this time on neither the integuments nor nucellus change appre- 

 ciably in appearance until the developing endosperm crushes them 

 against the wall of the ovary where the integuments form the 

 seed coat (fig. 42). 



The 3 vascular bundles of the ovary can be distinguished 

 entering the base of the nucellus almost immediately after its 

 initiation (fig. n, lower flower). The vascular bundle (indicated 

 by dotted line in fig. 14) consists of cells which are elongating 

 actively toward the nucellus, but the walls of which have not yet 

 begun to thicken. When the embryo sac is mature the nucellus 



