GROUP II. BRYOPHYTA. 



311 



shorter stalk ; its wall consists of a 

 single layer of cells which contain 

 chloroplastids when young ; internally 

 it consists of very numerous small cells, 

 each of which eventually gives rise to 

 a single spermatozoid. 



The spermatozoid is a cell, consisting 

 of a naked filament of protoplasm, spir- 

 ally twisted, thickened at the posterior 

 end where lies the nucleus, tapering at 

 the anterior end where it terminates in 

 two long cilia by means of which it 

 swims (Figs. 192, 193) ; the spermatozoids 

 are set free by the rupture of the an- 

 theridial wall, which usually takes place 

 at the apex of the antheridiuni. 



The archegonium is flask-shaped and 

 shortly stalked (Figs. 194, 195) ; it con- 

 sists of a slightly dilated basal portion, 

 the venter, and of a long slender neck. 

 The axis of the archegonium, when 

 young, is occupied by a central row of 

 cells ; the basal cell of this row, lying 

 in the venter, is the central cell of the 

 archegonium ; it grows considerably, and 

 eventually divides into two unequal parts, an upper and smaller, 

 the ventral canal- 

 cell, and a lower 

 and larger which 

 is the female re- 

 productive cell or 

 oospJiere : the upper 

 cells of the central 

 row constitute the 

 neck - canal - cells. 

 At maturity the 

 terminal cells, lid- 

 cells, of the neck 

 separate ; the neck- 

 canal -cells and the FlG - 193 --^ Antheridium of if arclwntia polymarplia ( Liver. 

 , , wort) iu optical longitudinal section: p parapbyses (x 90). 

 Ventral Canal-cell B Sparmatozoids ( x 600) : (after Strasburger). 



FIG. 192. Fitnaria hygromet- 

 rica (Moss). A Anantberidium 

 bursting -. a the spermatozoids 

 (x 350). B Spermatozoids 

 (x 800); bin the mother-cell: 

 c free spermatozoid of Poly- 

 trichutn. 



