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 the reserve-food is stored.  There are also intermediate states.  The position of the embryo in relation to the endosperm varies, sometimes it is internal, sometimes external, but the significance of this has not yet been established.

[v.02 p.0012]

The formation of endosperm starts, as has been stated, from the endosperm nucleus.  Its segmentation always begins before that of the egg, and thus there is timely preparation for the nursing of the young embryo.  If in its extension to contain the new formations within it the embryo-sac remains narrow, endosperm formation proceeds upon the lines of a cell-division, but in wide embryo-sacs the endosperm is first of all formed as a layer of naked cells around the wall of the sac, and only gradually acquires a pluricellular