SEXUAL REPRODUCTION. 



29I 



is much simplified, the neck-cells and the egg being the only 

 distinct parts of maturity. 



393. Gymnosperms. — In the gymnosperms the female 

 gametophyte is not large enough to burst the megaspore which 



spm 



Fig. 333.— Longitudinal section of the female gametophyte of Selaginella Martensii. 

 d, d, d, the body of gametophyte ; r, r, rhizoids (rudimentary) on its surface ; a, an 

 ovary whose egg failed of fertilization ; e, embryo developed from fertilized egg ; its 

 cell-structure is not shown, but the various members are begun ; s, suspensor ; st, stem; 

 /, /, primary leaves ; rt, root; /, foot ; e' , a younger embryo, with cell-structure shown, 

 the letter standing in large suspensor cell ; spm, wall of megaspore. Magnified 125 

 diam.— After Pfeffer. 



remains enclosed in the sporangium. Upon its surface are 

 formed several ovaries, each reduced to an egg and two to four 

 tiers of neck-cells (figs. 320, 321). 



394. Angiosperms. — In the angiosperms the female gam- 

 etophyte is so simplified that it is represented only by a few 

 cells, among which may be recognized at least one egg (e, 

 fig. 334), and possibly two others, s, s. The ovary has been 

 reduced to nothing but an egg, and the full development of 

 the gametophyte seems to be delayed until after the egg is 



