1 70 STRUCTURE AND LIFE HISTORIES 
archegonium approaches maturity it is seen to contain 
three cells; a long neck-canal cell, nearly filling the neck, 
an egg-cell or ovum, filling the venter, and between these 
two a ventral-canal cell. The egg is the female reproduc- 
tive cell. As it matures, the other two cells become disin- 
tegrated into a mucilaginous mass that fills the neck-canal. 
Since the archegonia contain the eggs they are the female 
reproductive organs. 
166. Reproductive Organs : Antheridia. Search among 
the rhizoids will reveal another class of organs, the 
FIG. 128. Portion of a cross-section of a prothallus of a fern (Adian- 
tum), showing an antheridium (an), and sporogenous cells within. (Drawn 
from preparation of E. W. Olive.) 
antheridia, globular and also having walls only one cell 
thick. These are the male reproductive organs. At 
maturity they contain a large number of tiny motile cells, 
composed chiefly of a coiled nucleus, and able to swim 
about in water by the vigorous lashing of numerous little 
thread-like cilia attached to one end. These are the 
sperms, or male reproductive cells (Figs. 128 and 129). 
156. Fertilization. Neither the eggs nor the sperms are 
able, independently, to reproduce their kind. In order 
