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 protoplasm arranges 

 itself in a sphal 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 



B 



an: 



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 archegonium 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 canal extending from the outside opening (mouth )to the ovum. 



