ropyle, but passing down the ovary wall and through the
placenta, enters at the chalazal end of the ovule. Such a method
of entrance is styled chalazogamic, in contrast to the porogamic or
ordinary method of approach by means of the micropyle.

_Embryology._

The result of fertilization is the development of the ovule into
the seed. By the segmentation of the fertilized egg, now invested by
cell-membrane, the embryo-plant arises. A varying number of transverse
segment-walls transform it into a pro-embryo--a cellular row of which
the cell nearest the micropyle becomes attached to the apex of the
embryo-sac, and thus fixes the position of the developing embryo,
while the terminal cell is projected into its cavity. In Dicotyledons
the shoot of the embryo is wholly derived from the terminal cell of
the pro-embryo, from the next cell the root arises, and the remaining
ones form the suspensor. In many Monocotyledons the terminal cell
forms the cotyledonary portion alone of the shoot of the embryo, its
axial part and the root being derived from the adjacent cell; the
cotyledon is thus a terminal structure and the apex of the primary
stem a lateral one--a condition in marked contrast with that of the
Dicotyledons. In some Monocotyledons, however, the cotyledon is not
really terminal. The primary root of the embryo in all Angiosperms
points towards the micropyle. The developing embryo at the end of the
suspensor grows out to a varying extent into the forming endosperm,
from which by surface absorption it derives good material for growth;
at the same time the suspensor plays a direct part as a carrier of
nutrition, and may even develop, where perhaps no endosperm is formed,
special absorptive "suspensor roots" which invest the developing
embryo, or pass out into the body and coats of the ovule, or even into
the placenta. In some cases the embryo or the embryo-sac sends
out suckers into the nucellus and ovular integument. As the embryo
develops it may absorb all the food material available, and store,
either in its cotyledons or in its hypocotyl, what is not immediately
required for growth, as reserve-food for use in germination, and by so
doing it increases in size until it may fill entirely the embryo-sac;
or its absorptive power at this stage may be limited to what is
necessary for growth and it remains of relatively small size,
occupying but a small area of the embryo-sac, which is otherwise
filled with endosperm in which