INTRODUCTION. 7 



the latter have to depend upon external agencies for aid in 

 fulfilling their mission. The antherid is ruptured by pressure 

 from within forcing off the lid-cell, followed by the escape of the 

 antherozoids (Plate 5). 



The archegones consist of an enlarged basal portion em- 

 bedded in the prothallium, and containing an egg-cell 

 (posphere\ From the oosphere a canal runs through circular 

 cell-walls and communicates with the air. The canal is filled 

 with a mucilage resulting from the breaking up of cells which 

 formerly occupied the centre. As this mucilage pours out from 

 the mouth of the canal, a discharge of an acid excretion attracts 

 the antherozoids, and they find their way through the mucilage 

 in the canal, until coming to the egg-cell they pierce and 

 fertilize it. The egg-cell then invests itself with a cell-wall and 

 begins to develop into an embryo, from which minute and 

 simple fronds are produced in succession, each getting less 

 simple than its predecessor, until finally they attain to the form 

 and degree of subdivision characterizing the adult fern on which 

 the spore was produced which developed into the prothallium. 

 And so the cycle is completed. The first generation gave rise to 

 the second by a purely vegetative process ; the second genera- 

 tion produced the third by a sexual process ; and the third in 

 turn produces a fourth vegetatively again. 



In the following pages we propose to describe the native 

 species of ferns and some allied plants which, though differing 

 from the ferns greatly in appearance, agree with them in their 

 methods of reproduction and in other respects. This group, 

 known to botanists as the Pteridophytes, are the most highly 

 organized of the flowerless plants (Cryptogamia\ differing 

 from the mosses, the seaweeds, and the fungi of all kinds in 

 the fact that, whilst these are built up of simple cells only, the 



