CYCADALES 



133 



entire lack of starch. The layer next within is also somewhat 

 differentiated, its cells being much larger than those of the outer 

 layer, but much smaller than those of the ordinary endosperm cells 

 of the remaining vegetative portion of the gametophyte. Many cells, 

 like the evenly shaded one in fig. 134, contain tannin. 



135 



136 



Figs. 135-138. — Dioon edule: development o£ the archegonium; fig 135, the 

 archegomum initial (November); fig. 136, central cell and neck cell (December); 

 fig. 137, archegonium in January; fig. 138, upper portion of archegonium in March; 

 all X88. — After Chamberlain (46) 



The development of the archegonium has been described for 

 Cycas revoluia by Ikeno (27) and for Dioon edule by Chamberlain 

 (46) ; isolated stages are known in other forms. In Dioon edule the 

 archegonium initials, usually four or five in number, may be seen 

 early m November, more than five months before fertilization. The 

 initial soon divides, giving rise to a primary neck cell and a central 



