SPERMATOniYTES: AKGIOS PERMS 



207 



more or less filled with nutritive 

 cells, which are often organized 

 into a compact tissue (Fig. 179). 

 These nutritive cells do not cor- 

 respond to the endosperm of 

 Uymnosperms, although they re- 

 receive the same name. In Gym- 

 nosperms the endosperm is main- 

 ly formed before fertilization and 

 is the nutritive body of the female 

 gametophyte; while in Augio- 

 sperms it is formed after fertiliza- 

 tion and is probably not a part 

 of the gametophyte. As the 

 endosperm of Angiosperms is a 

 product of what appears to be 

 fertilization, it would seem 

 proper to regard it as sporo- 



phyte tissue, but its real character is still under discussion. 



The antipodal cells probably represent nutritive cells 



of the gametophyte. Sometimes they disappear very soon 



after they are formed; but sometimes they become very 



Fig. 178. End of embryo-sac of 

 Silphium, showing double fer- 

 tilization : sy, synergid, the 

 other having been destroyed by 

 the pollen-tube ; o, egg with 

 coiled male cell (sp,) lying 

 against its nucleus ; e, endo- 

 sperm cell, with large coiled 

 male cell (sp a ) lying against it. 

 —After Land. 



Fig. 179. One end of the embryo-sac in wake-robin (Trillium), showing endosperm 

 (shaded cells) in which a young embryo is imbedded.— After Atklssok. 



