FEMALE GAMETOPHYTE 455 
extends beyond the nucellus, and its free margin flares open, thus 
forming an open micropyle that leads into the pollen chamber. 
Female Gametophyte. — Although four megaspores are formed 
in the megasporangium, only one of them develops a gameto- 
phyte, the others being destroyed and used for food by the one 
that develops. During the first season the surviving megaspore 
enlarges and becomes multinucleate. With the megaspore in this 
Fic. 404.— Development of the ovule and pollen tubes in the Pine. C, 
section through an ovuliferous scale, showing the bract behind and a section 
of an ovule (s) on its inner face, the megaspore being shown at m; D, an 
ovule with female gametophyte (f) mature, showing eggs at e, ovule wall 
consisting of nucellus and integument at w, and pollen grains growing tubes 
through the nucellus at (p). 
condition the ovule passes the winter. Early next spring growth 
is resumed, and by about the first of June of the second season 
the gametophyte is complete, consisting of 250 or more cells and 
bearing a number of archegonia (usually two to five) at the 
micropylar end (Fig. 404.) The eggs are usually ready for 
fertilization about the first of June of the second season. While 
the female gametophyte is developing, the male gametophyte is 
completing its development in the pollen chamber and the pollen 
