22 
PHARMACEUTICAL BOTANY 
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 arcliegonia make 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 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 
Fig. 5. — 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 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. 
During wet weather the mature antheridial wall bursts open and 
the many ciliated spermatozoids escape into the water. These mov- 
ing in the water are drawn by the chemotactic malic acid to the 
mouths of the archegonia of another prothallus and, passing down 
the canal of each of these, gather around the ovum. One, probably 
the best adapted, fuses with the ovum and fertilizes it forming an 
oospore or fertilized egg. 
