PHANEROGAMIA, 231 
end of which an embryo soon begins to form by the fission 
of cells in three planes (Figs. 131, B, and 132, I to IV). 
488. At first the embryo is a minute rounded cell-mass 
attached to the end of the row of cells, and in some plants 
it passes but little beyond this stage until after the ripen- 
ing of the seed. In most cases, however, the cell-mass con- 
tinues its growth until it has formed a little stem bearing 
E# 
F 
Fic. 133.—Magnifled sections of seeds, showing embryos and endosperms. A, 
Oat; B. Sedge; C, Coffee; D, Marsh-marigold; #, Bitter-sweet; F. Goosefoot; 
G, Nettle; H, Oak; J, Sweet Pea; J, a Mustard. In A to D, small or minute 
embryo in large endosperm; E to G, larger embryo and smaller endosperm; 
H to J, large embryo and no endosperm. 
rudimentary leaves above and a root below. There are to 
be found all degrees of simplicity in the embryos of An- 
giosperms, from the rounded cell-mass (thallus) to the well- 
formed plantlet provided with distinct root, stem, and 
leaves. 
489. While these changes are going on, cells arise in the 
basal part of the embryo-sac and increase rapidly, generally 
filling up a considerable part of its cavity. These cells 
