THE FILMY FERNS. 



221 



Fertilization takes place in the usual way : an antheroxoid escapes 

 from the enclosing" antheridium and swims to the neck of the 

 archegonium hy means of the small amount of water which is 



always present in the soil where they grow. 

 It makes its way down th-e canal of the arche- 

 gonium (fig. 37, c) and unites with the egg- 

 cell at its base and from this union a young 

 fern plant arises. Occasionally in the genus 

 Trichoiiiaiics the sexual organs appear upon a 

 filamentous prothallus. instead of upon the 

 strap-shaped form. 



Various forms of asexual reproduction oc- 

 cur. Figure 36, g, shows a cluster of brood- 

 bodies or gemm(e which have formed at the 

 apex of the prothallus. One of these bodies, 

 enlarged, would show the nuclei and chloro- 

 phyll granules within its cells. 



About 160 species of the Hymenophyllacese 

 have been described. Thev are the aristo- 



FiG. 36. Prothal- 

 lus. (a) antheridia. 

 {b) archegonia. {g) 

 gemmae. 



Fig. 27- Archegonium. (c) canal; 

 egg-cell at its base. 



crats of the fern world. Finable to accommodate themselves to 

 variations in heat and humidity, their favorite habitats are the 

 warm, moist forests of the tropics, but in these restricted localities 

 they produce forms of such rare beauty as to make any fern lover 

 feel that he has been well repaid for the pains of a pilgrimage to 

 their haunts. 



