(343) 
The embryo-sac at the time of fertilization occupies but a 
small oval space near the micropyle. At this stage it con- 
sists of the usual structures though with certain individual 
characteristics worth noting (jig. 35). The most conspicuous 
element of the embryo-sac is its endosperm nucleus. This 
is relatively large; it is marked also by its chromatin content 
and large nucleolus. The cytoplasm surrounding the nucleus 
is quite dense and radiates from the center in strands sepa- 
rated by numerous vacuoles. The egg-apparatus in its gen- 
eral form and structure conforms to the types already de- 
scribed. The nuclei and the vacuoles of the synergids are 
quite small as compared with those observed in some of the 
other forms. In this case antipodals were observed, though 
only as vestiges (jig. 35) 
Immediately after fertilization certain marked changes may 
be seen in the character of the embryo-sac. It expands, 
much as in other cases, into a sac-like structure, but soon 
becomes filled with numerous refractive starch-grains, among 
which occasional free nuclei are easily seen (fg. 36). The 
nuclei and the starch-grains are both more abundant in the 
upper portion of the embryo-sac. The nuclei have lost some 
of the features which characterized the original endosperm 
nucleus, being here almost devoid of any chromatic sub- 
stances, aside from the large nucleolus. The starch which 
forms so conspicuous a part of the endosperm is, however, 
of only transient duration. The endosperm expands rapidly 
toward the chalaza and laterally and soon becomes a thin 
layer of vacuolated protoplasm, in which the nuclei are still 
free. The starch at this stage (fig. 39) has entirely disap- 
peared. The lower extremity of the endosperm soon as- 
sumes the appearance of a haustorium. In this condition it 
appears as a finger-shaped, vacuolated mass, containing 
several nuclei (g. 39), before which the tissue of the nucellus 
breaks down. This appendage, however, disappears in the 
course of development (jg. gz), but in the case just cited the 
nucellus presents no further obstactle to the development of 
either endosperm or embyro. At this stage the endosperm 
