222 
A TEXTBOOK OF GENERAL BOTANY 
stalk, the funiculus, and is surrounded by two cellular mem- 
branes, the znteguments. The ovule may be straight, but more 
usually it is bent back on the funiculus, with the outer integu- 
ment fused to the funiculus, as shown in Fig. 227. The end 
of the nucellus that is attached to the funiculus is known 















= 
SEA 
KK igh ee oN 
KA ZGLBS oR Io SOS NN 
Weegee tsOtes oo VSG 
lag (SE KH VHT, ues 
Be iescrarceesennoe,\\\ eum 1 | 
H/ Oia Peirene ween couiey \Y\ ia iat 
eee 
a-+y Lifes Here ec ee IH tal 
BOA 
N - ae) y g 
p- af SH 
eae VSLTT II NH 
Fa 
Oran) Yo TH TN ay 
pers D> OH He nies 
poe se 
Pm) ne i 
3S 
(0) 
eros 
CS a 
=f LW 
Fic. 227. Ovule of Zephyranthes rosea 
Jf, funiculus ; m, micropyle; 0, outer integument ; 
i, inner integument; n, nucellus; es, embryo sac ; 
8s, synergid; e, egg; p, polar nucleus; a, an- 
tipodal cell. (x 115) 
as the chalazal end. At 
the opposite end of the 
ovule there is an open- 
ing, the micropyle, which 
extends through the in- 
teguments, and through 
which the pollen tube 
passes when it enters 
the ovule. In the nu- 
cellus at the micropylar 
end is the embryo sae, 
which is usually some- 
what oval. Within this 
embryo sac there are 
six cells and two free 
nuclei, the polar nucle. 
The cells occur in a 
group of three at the 
micropylar end and an- 
other group of three at 
the chalazal end. The 
three at the micropylar 
end consist of a large cell, the egg, and two small cells, the syner- 
gids. At the chalazal end of the sac the three cells are usually 
small and are known as antipodals. The two polar nuclei origi- 
nate one at each end of the embryo sac, but later move to 
the center. 
Fertilization. When the pollen tube reaches the ovule, it 
grows through the micropyle (Fig. 228) and then into the em- 
bryo sac, where it discharges the two male nuclei. One of these > 
enters the egg and fuses with the nucleus of the egg. This 
