400 
STRUCTURE AND LIFE HISTORIES 
tudinal section is made of a mature ovule (Fig. 297), the 
remainder of the nucellus appears only as a thin mem- 
brane adhering to the outer surface of the prothallus, or 
endosperm, as it is here called. When the egg fails to 
become fertilized the gametophyte may protrude, develop 
chlorophyll, and lead a brief, semi-independent existence. 
mi 
0.1, 3 
FIG. 297. Photograph of a longitudinal section of an ovule of Macro- 
zamia Moorei. mi, micropyle; n.c, nucellar cap; a.r, archegonia (the 
venters only showing); il, inner, hard layer, o.l, outer, fleshy layer of the 
integument; g, gametophyte; p.c, pollen chamber. Enlarged from D, 
Fig. 296. 
Several archegonia develop in the apical end, imbedded 
in the tissue of the prothallus, and with their neck-canals 
opening at the surface into a pollen-chamber (Fig. 297). 
They resemble somewhat the archegonia of the lower orders 
