16 
Each archegonium is flask-shaped and contains 
in its lower swollen portiona single female 
sexual cell—the ovum or egg-cell (Es.). 
The sperm isa long spirally coiled body, 
blunt behind and tapering to a point in front 
where it bears fine hair-like processes termed 
cilia, by the vibratile movements of which it 
moves about in the water which saturates the 
soil in which the prothalli are growing. Sooner 
or later it comes into the neighbourhood of an 
archegonium, being attracted to it by the 
mucilaginous exudations from the neck. It 
enters the archegonium by the neck and 
fuses with the egg-cell. Thus fertilization is 
accomplished. 
From the fertilized egg-cell, what is com- 
monly known as the ‘ Fern Plant’ is produced. 
This is at first extremely small and grows at 
the expense of the food-material supplied by 
the prothallus to which it remains attached till 
it is able to spread its own roots and live 
independently. (Fig. 5.) 
From what has been said above it will be 
evident that there are two stages or phases in 
the life-history of the Fern :—(1) The short- 
lived prothallus which grows from the spore 
and bears the sexual cells, and (2) the ‘ Fern 
