54 COMPARATIVE EMBRYOLOGY OF THE RUBIACEAE 
they are of less importance than in the other plants studied, is in- 
dicated by the distribution of starch. In the unopened flower the 
embryo-sac is crowded with this food material, which is, however, 
absent from the rest of the ovule. As the flower opens, and at 
the time of fertilization, the starch disappears from the embryo-sac, 
first from the egg pole, so that in an old flower starch is entirely 
absent from the embryo-sac, but has commenced to accumulate 
at the chalazal end of the ovule. After fertilization, starch reap- 
pears in the antipodal cells, and then in the growing endosperm, 
so that when the latter has considerably increased (p/. 13, fig. 6), 
the former are very rich in starch content. In this connection it 
is to be noticed, also, that the subsidiary archesporial cells soon 
disappear, and take no further part in the development of the 
ovule. They are, in fact, quite lost to view when the embryo-sac 
contains but two cells. The endosperm nucleus lies appressed 
against the egg cell for some time before division. The endosperm 
is of the parietal type )۸ 13, fig. 6), and its behavior is similar 
to that of the same structure in Diodia Virginiana, as is also true 
of the integument. E 
The shape of the ovary is such that the chalazal end of the in- 
tegument becomes folded over the strophiole, the whole produc- 
ing the curious effect shown in p/. 13, fig. 8. 
The embryo is slow in developing, and no haustorial out- 
growths occur. The cells of the suspensor are at first short, and 
disc-shaped and later lengthen, bringing the embryo deeper in 
the endosperm )۸ 13, fig. 9). That the suspensor is not an 
organ of only mechanical significance may be inferred from the 
occurrence in it of a great deal of starch up to the time, at least, 
when the cotyledons are well started. 
Richardsonia pilosa 
(PLATE 13, FIGURES 11-18) 
Material in cultivation at the New York Botanical Garden. 
In the main, this plant agrees with the two species of Diodia 
as to the development of the ovule and archesporium, and of the 
embryo. The following important points of difference are to 
be noted. 
The functional megaspore enlarges and. develops into the 
