1918] DUDGEON—RUMEX CRISPUS 3905 
The sequence of development of the floral organs is centripetal, 
although the petals and carpels are somewhat delayed (figs. 1-7). 
The sepals appear as 3 thick prominences, and rapidly grow up 
over the young flower. The 3 petals appear almost simultaneously 
with the stamens, which they closely resemble at first (figs. 3, 8, 9). 
The 6 stamens appear in pairs, the 2 of each pair arising so close 
together that their bases are joined to each other and to the sepal 
opposite which they lie (fig. 9@). The carpels first appear as a 
thick ring about the base of the nucellus, but the latter develops 
much more rapidly and is not inclosed by them until the megaspore 
mother cell is considerably enlarged (figs. 4-7). The carpels 
develop as a continuous ring led by 3 growing points (fig. 8), until 
the ovarial cavity is inclosed, when the 3 points continue separately 
to form the styles and stigmas (figs. 6, 7). The styles are reflexed 
so that the much branched stigmas are finally placed between the 
bases of the anthers. 
The inner integument appears during the prophase of the first 
reduction division (fig. 6), and the outer appears with the homoio- 
typic division (fig. 7). Both are 2-layered from the beginning. 
The inner grows up beyond the nucellus, and turns inward to close 
up and form the micropyle. The outer integument never extends 
much beyond the tip of the nucellus. During the development of 
the embryo sac, the cells of the outer layer of the outer integument 
and the epidermis of the ovary thicken, lose their contents, and 
form a continuous impervious layer (fig. 7; see also figs. 13, 14). 
This process is significant, because it leaves only the chalazal region 
of the ovule as a point of intake for nutrient materials. 
MEGASPOROGENESIS.—The terminal cell of a definite axial row 
in the nucellus enlarges as the archespore (fig. 22). It soon divides 
to form the primary parietal cell and the megaspore mother cell 
(fig. 23). The parietal cell divides twice by anticlinal walls to form 
a cap of 4 cells (figs. 24, 28). Occasionally any or all of these cells 
may divide by a periclinal wall (figs. 25, 32). Less frequently, a 
cell or two of the adjacent epidermis may also divide periclinally 
(figs. 33, 36, 44). Occasionally there are two archesporial cells, 
and in one ovule there was a mass of probably 7 archesporial cells, 
a few of which had undergone the first division. In the most 
