GENERATIVE APPARATUS OF FERNS. 



381 



of the prothallium, within which is a large intercellular space 

 containing a peculiar cell (the Germ-cell), and opening exter- 



Fig. 194, 

 ABC 



■SSV^ 



Development of "the Antheridia and Antherozoids of Pteris ser- 

 rulo.ta : — a, projection of one of the cells of the Prothallium, 

 showing the Antheridial cell, b, with its Sperm-cells, e, within 

 the cavity of the original cell, a ; — b, Antheridium completely- 

 developed ; a, wall of Antheridial cell ; e, Sperm-cells, each en- 

 closing an Antherozoid ; — c, one of the Antherozoids more highly- 

 magnified, showing a, its large extremity, b, its small extremity, 

 d, d, its ciha. 



Fig. 195. 

 A B 



Archegonium of Pteris serrulata : — A, as seen from above ; 



a, a, a, cells surrounding the base of the cavity ; b, c, d, successive 

 layers 'of cells, the highest enclosing a quadrangular orifice : — 

 B, side view, showing a, a, cavity containing the Germ-cell, a ; 



b, b, walls of the Archegonium, made up" of the four layers of 

 cells, b, c, d, e, and having an opening, /, on the summit ; c, c, 

 Antherozoids within the cavity ; g, large extremity ; h, thread- 

 like portion ; i, small extremity in contact with the germ-cell, 

 and dilated. 



nally by an orifice at the summit of the projection ; but when 

 fully developed (Fig. 195), it is composed of from ten to twelve 



