RICHARDSONIA PILOSA 55 
embryo-sac zz situ. In lengthening, however, it grows forward, 
and destroys the nucellar cap, so that these cannot be seen after 
the embryo-sac nucleus divides. No migration, strictly speaking, 
takes place, so that the antipodal cells appear in the position pre- 
viously occupied by the archesporium. The few reduced sub- 
sidiary megaspore mother-cells are soon absorbed and are lost 
to view. 
By the usual number of divisions the eight embryo-sac nuclei 
are formed, and the egg apparatus, polar nuclei and antipodal 
cells arrange themselves in an oval cavity. The antipodals are 
constantly three in number, and are in this plant all nearly of a 
size (figs. 14, 15). For some time they possess a large, deeply stain- 
ing nucleus, finely granular dense cytoplasm, and a vacuole at 
their free ends, and present the appearance of certain glandular 
cells, especially the stigmatic cells in some plants, and of syner- 
gidae. This fact is important, as it indicates a considerable degree 
of physiological activity on the part of the cells. 
After fertilization the embryo develops slowly, forming first by 
transverse cell divisions a row of disc-formed cells. The suspensor 
remains always a short organ, with no special adaptations. The 
endosperm is at first parietal, but early fills the cavity by equal 
centripetal growth on all sides. At such time as this occurs, there 
appear at the apex of the embryo certain very much enlarged.cells 
of endospermic origin, with nuclei considerably greater than those 
of the rest of the endosperm cells ( £g. 78). Beyond their size, as 
just indicated, these cells do not present any peculiarities, and it is 
therefore difficult to any whether they possess any special physio- 
logical peculiarities, although this seems probable. They corre- 
spond in general to similarly placed cells in other types described, 
as having a centripetally developing endosperm, differing from 
them chiefly in size. 
As the ovule enlarges after fertilization the limiting cells of the 
strophiole take on the brown coloration already noted in Diodia 
Virginiana. This change spreads to the cells surrounding the end 
of the vascular bundle. The peculiar function of these cells, if 
such they possess, remains problematical. It is certain, however, 
that they exert no unfavorable influence on the passage of food 
solutions, whether'they have any positive value or not. 
