LIFE HISTORY OF THE MALE FERN 
43 
antheridia, or male sexual organs, archegonia , or female sexual organs, 
and rhizoids or hair-like absorptive structures. The antheridia 
appear three to five weeks after spore germination. They are hemi¬ 
spherical in shape and are situated among the rhizoids toward the 
posterior end. Each antheridium consists of a three-celled wall 
which completely surrounds the spermatocytes or mother-cells of the 
spermatozoids. Within each spermatocyte the pfotoplasm arranges 
itself in a spiial fashion forming a spermatozoid , a spiral, many 
ciliated, male sexual cell. From two to four weeks after the matura¬ 
tion of the antheridia, the archegonia make their appearance toward 
Fig. 18.— A, median longitudinal section through immature antheridium, and 
cell of prothallium showing prothallial cell (p), and antheridial wall surrounding a 
number of spermatocytes; B, similar section through mature antheridium and cell 
of prothallium showing fully developed spermatozoids ( sp .) enclosed by wall of 
antheridium. Both highly magnified. 
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 anther¬ 
idia of the same prothallium. Each mchegonium is composed of a 
venter , neck, neck canal-cells, ventral canal-cell, and ovum or egg-cell. 
The neck is composed of cells arranged in four rows, forming a cylin¬ 
der, 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 maturation of the archegonium, 
the canal cells are transformed into a mucilaginous substance which 
fills a can&l extending from the outside opening (mouth )to the ovum. 
