SEED-BEARING PLANTS 
439 
392. The Female Gametophyte. Megaspores are 
probably not formed in tetrads by two divisions of a 
megaspore-mother-cell, but the ancestral-cell of the female 
a. 
FIG. 325. Dog's-tooth violet (Erythronium}. i, embryo-sac, binucle- 
ate stage, the two nuclei dividing; 2, four nucleate stage; 3, mature embryo- 
sac (es); the pollen-tube (p.l) has reached the egg-apparatus and fertiliza- 
tion has just taken place; the male and female nuclei are both visible in 
the fertilized egg. The synergids are not shown 5^4, polyembryony; four 
embryos have developed from the embryogenous tissue, one embryo at 
the left of a not shaded; 5, longitudinal section of an embryo (em); s, 
suspensor; i, 2, and 5, E. alb-idum (after Schaffner); 3 and 4, E. americanum 
(after Jeffrey). Only one of the multiple embryos persists. 
gametophyte (arches porial cell] functions directly as a 
megaspore, without division. In very early spring the 
megaspore begins to germinate, increasing in size, and 
