43 



Plate 5. 



Moist Cliff with liverworts. Table Mountain, 3000 feet. Dec. 

 Upper part : Plagiochila natalensis Pears., with plants of Disa longicornu. 

 Lower part: Marchantla polymorpha L. ( $ ), with Crassula margaritifera (in front) 



Division XII. BRYOPHYTA. 



Plant consisting either of a thallus only or provided 

 with stems and leaves ; no true roots but merely rhizoids 

 and no real vascular tissue ; the nerves of the leaves, where 

 present, formed of strands of elongated cells. 



The spore on germination produces a simple or 

 branched thread of cells, called the protonewva. On this 

 appear lateral buds, from which originate the adult plants. 

 Each plant bears two kinds of sexual organs, viz. antheridia 

 and archegonia. The antheridiu-m produces spevwiatozoids 

 and the archegonium an oosphere (egg-cell). The sperma- 

 tozoids are liberated only in water, hence in drier localities 

 usually after rain or heavy dew. Being provided with two 

 cilia and attracted by some substance secreted by the 

 archegonium (e.g. sugar) they propel themselves towards its 

 mouth and finally enter it. The product of the fertilised 

 egg-cell, the embryo^ develops into the sporogonium^ the 

 so-called moss capsule, which remains permanently con- 

 nected with the gametophyte, being nourished by it in the 

 same manner as a semi-parasite. 



The sporogonium develops a vast number of spores, 

 and when ripe opens in various ways, the spores then 

 recommencing the cycle of life. 



The bryophytes form two natural classes, viz. the 

 Hepaticae (liverworts) and the Musci (mosses), which, 

 apart from other characters, principally differ in the mode 

 of development of the sporogonium. 



6—2 



