Occurrence and Development of a Filiform Apparatus in the Egg of Plumbago Capensis

Micropylar wall extensions in the egg of Plumbago capensis arise as small pegs of periodic acid‐Schiff's‐positive material soon after the egg is organized. These inward projections of egg wall increase in size, becoming extensive near anthesis. Some branching of the filiform apparatus occurs. In mature embryo sacs the micropylar portion, with the lowermost portion of the egg included, becomes entrenched in the nucellus. The possible significance of this “gametic transfer cell” is discussed in relation to the apparent absence of synergids from the reduced embryo sac of Plumbago .