FILICES. 257 



base of which is a germ-cell, the division and ultimate 

 development of which depends upon the access of the 

 antherozoid through the canal of the archegonium, which 

 is filled with a mucilaginous protoplasm at maturity. 



FIG. 201. Pinnule and sorus, laid open, of Trickomattes. 



From the fertilized germ-cell an independent Fern-plant 

 is developed with its fronds and sporangia. 



We have thus in the (i) Fern-plant bearing spores de- 

 veloped from the fertilized archeg9nium, and in the (2) 

 orothallium developed from the spore-bearing antheridia 

 and archegonia, an alternation of generations in which 

 the asexual generation, that is to say the Fern-plant 

 which does not itself bear sexual organs, greatly pre- 

 dominates both in bulk and duration over the sexual 

 generation, that is to say, the prothallium bearing the 

 antheridia and archegonia. The antheridia and arche- 

 gonia of Ferns require a high magnifying power for their 

 examination. Their true nature has been understood 

 only within the last forty years. 



Ferns are great favourites for parlour cultivation under 

 glass shades, which prevent the moisture which they 

 require for their healthy growth from evaporating. Some 

 foreign species, growing in warm, moist climates in the 

 Southern hemisphere, form tall, woody stems, 40 to 50 

 feet in height. These are called Tree-ferns. 



A transverse section of the trunk (caudex) of any' of 



O.B. s 



