( 361 ) 
the divisions of the spore-mother-cell have been completed the 
integuments have almost enveloped the nucellus. The pro- 
portions of the parts of the ovule are indicated by text-figure 
, i. 
After having undergone a period of rest the mother-cell 
divides to form four potential megaspores. During this 
period of growth the development of sterile tissue has left 
the sporogenous cell deep in the nucellus. After the first 
division of the spore-mother-cell the two daughter-cells again 
divide, but not simultaneously. The lower one divides first 
and the division is completed before the division of the 
upper one (fg. 778). The lowermost spore of the four thus 
formed gives rise to the embryo-sac; the rest disappear. 
The development of the embryo-sac takes place by the 
usual process (jigs. r1g-r2r). The embryo-sac of eight 
cells expands in its upper part and the differentiation of the 
egg-apparatus is begun by the formation of walls about the 
nuclei and the increase of cytoplasmic substance. This pro- 
cess goes on more slowly at the antipodal end of the sac. 
The polar nuclei soon come into contact about midway and 
remain thus for some time (figs.72z-z22 a). In this case the 
embryo-sac at the time of fertilization presents about the 
same appearance as other forms which we have noticed. 
The egg-apparatus and the antipodals are essentially similar 
to some of those already studied, though the cytoplasm sur- 
rounding the polar nuclei is thin and devoid of starch. The 
polar nuclei increase in size gradually and probably fuse, 
though a single endosperm nucleus was not observed at any 
time. 
After fertilization the endosperm nuclei multiply to the 
number of ten or twelve before the odspore divides. The 
cytoplasm becomes distributed in the form of a hollow sac 
(fig. 123) at first, but later assumes a cellular character and 
becomes solid. As the endosperm begins to expand, the 
nucellus where in contact with it disintegrates, and the effect 
of the decomposing influence is apparent for some distance 
around the embryo-sac, by the modified character of the cell- 
