98 



THE LIVING CYCADS 



41 



43 





•■;0v:6*-.-::?i-X.-'vV>, 

 ■. -4'. - ".-•Tt *.■ -^"v :•>- 





"i^ ■ v*?" *^ •■.■.-.!' '!i 



44 



Figs. 41-45. — Dioon cdulc: development of the archcgoniuni: 

 iMg. 41, the archegonium initial; Fig. 42, the archegonium initial di- 

 Nnded, forming a primary neck cell and a central cell; Fig. 43, the pri- 

 marj- neck cell divided, giving rise to the two neck cells; Fig. 44, the central 

 cell divided, giving rise to the ventral-canal nucleus (the smaller nucleus 

 at the top) and the egg, with the larger nucleus; Fig. 45, the archcgonia 

 at a later stage, showing the depression (archegonial chamber) above the 

 archegonia. Figs. 41-44 highly magnified; Fig. 45 much less magnified. 



