264 
MORPHOLOGY 
kind, but the megaspores are represented by four nuclei. The mother 
cell, therefore, seems to behave like a megaspore in producing the female 
gametophyte, and the hypodermal initial thus directly produces the 
female gametophyte. Of course this really means that four mega- 
spores enter into the formation of the gametophyte, and the two 
successive reduction divisions are the first two divisions in the forma- 
tion of the gametophyte. 
FEMALE GAMETOPHYTE 
Development. The development of the female gametophyte of 
angiosperms begins with free nuclear division, as in gymnosperms, but 
the nuclei thus produced are definitely eight in number, following three 
successive divisions from the nucleus of the megaspore. It is in this 
free nuclear stage that the egg is differentiated, which is the condition of 
Gnelum, except that here the nuclei are much fewer in number. In 
FIGS. 589-591. Development of female gametophyte of angiosperms, as shown by a 
lily: 589", megaspore (in the ovule); 590, first division; 591, second division. 
connection with these free nuclear divisions two remarkable features 
appear. One is the polarity exhibited by the nuclei. After the first 
division the two nuclei separate and pass to the poles of the embryo sac, 
one to the micropylar end, and the other to the antipodal end (fig. 590). 
There follow two successive divisions, so that first two (fig. 591) and then 
four (<ig. 592) nuclei are produced at each pole of the sac. The other 
