LIFE HISTORY OF THE MALE FERN 69 
the protoplasm arranges itself in a spiral fashion forming a 
spermatozoid, a spiral, many ciliated, male sexual cell. From two 
to four weeks after the maturation of the antheridia, the arche- 
gonia makes their appearance toward the indented apex of the 
lower prothallial surface as outgrowths of the prothallial cushion. 
Since they appear later than the antheridia they are not likely 
to be fertilized by spermatozoids from the antheridia of the same 
prothallium. Each archegonium is. composed of a venter, neck, 
neck canal-cells, ventral canal-cell, and ovum or egg-cell (see Fig. 
38B). The neck is composed of cells arranged in four rows, 
forming a cylinder, one layer of cells thick. This protrudes from 
the surface of the prothallium and encloses the neck canal-cells 
and ventral canal-cell. The ovum is embedded in the prothallial 
cushion just beneath the ventral canal-cell. Upon the matura- 
tion of the archegonium, the canal cells are transformed into a 
