{Structure and Reproduction. 
—— 
It is not intended in the present volume to enter into 
any detailed description of the structure and mode of 
reproduction of ferns ; but a few words on the subject 
may not be out of place. 
The name “ Fern ” is given by botanists to a certain 
division of plants which do not bear flowers, but which 
produce their seeds or germs either on the leaves 
themselves, or on a separate naked branch of the leaf 
devoted to that purpose. 
These germs or Spores are very minute, angular 
bodies, contained in circular or oval vessels called 
Tliecce or Sporangia, (see page 60), which are in most 
cases encompassed by an elastic ring or Annulus. 
The theca: usually grow in clusters, called Sori. 
When mature, the annulus dries up, contracts, and 
bursts open, thereby rending asunder the theca and 
ejecting the spores contained within. In such of the 
species as have no annulus, the thecae are two-valved, 
and open of themselves when mature* 
Each of the spores which falls on suitable ground, 
begins to germinate, and sends downwards hair-like 
roots ; and, nourished by these, gradually developes 
into a flat green expansion termed the Prothallium. 
On the under surface of this prothallium, appear in 
course of time two sets of organs, the Archegonia, and 
the Antheridia. The archegonium appears at first as a 
