262 



PART IV. CLASSIFICATION. 



sents. Beneath, the oogonium proper is a node, the central cell of which 

 constitutes the stalk-cell of the oogonium, whilst the five peripheral cells 

 of the node grow out into filaments which gradually become spirally 

 twisted and enclose the oogonium ; the tips of these filaments project at 

 the free end of the oogonium, constituting the crown or corona, and are cut 

 off from the rest of the filaments either by one transverse wall, so that the 



FIG. 150. CTiarafragilis, reproductive organs (after Strasburger). A Median longitu- 

 dinal section through a leaf (gametophyll) r, and the sexual organs which it bears; a an- 

 theridium, borne on a nodal cell na by the stalk-cell p ; m the manubria ; ob an oogonium, 

 borne on a nodal cell no and an internodal stalk-cell po ; c corona (all x 90). B spermato- 

 zoids(x540). 



