114 



MONOCOTYLEDENOUS ANGIOSPERMS 



Development of the Female Gametophyte from the Macro- 

 spore. The macrospore divides into two cells, the two cells 

 into four, and the four cells into eight, all of which are con- 



FIG. 68. Lilium canadense. A, Development of male gametophyte and 

 sperms; showing the pollen grain with nucleus, the nucleus divided to form 

 the antheridial and tube cell. The next four figures show the formation of 

 the pollen tube, in the last figure the antheridial cell has divided to form two 

 sperms, the tube nucleus is at the end of the tube. B, Development of the 

 female gametophyte and egg cell. Megaspore with nucleus, formation of 

 two nuclei, four nuclei formed, eight nuclei formed, two nuclei fused to form 

 the endosperm nucleus at the center, three antipodal cells above, the two 

 lower synergids or helpers and- the egg cell. 



