276 



THE BRYOPHYTES 



283. The sexual organs. The sexual organs of the bryophytes 

 are many-celled. They are male and female and each consists 

 of a cellular case, or capsule, in which 

 are formed the respective gametes, which 

 are sperms and eggs. It will be remem- 

 bered that the sexual organs of the thai- 

 lophytes are, with very few exceptions, 

 one-celled. The conspicuous exceptions 

 are the plurilocular sexual organs of the 

 lower brown algae (see Ectocarpus, Sec. 

 235) and the antheridium of the stone- 

 worts (Sec. 230). 



The sperm-producing organ, or anther- 

 idium. The antheridium (Fig. 243) is a 

 stalked, oval or elliptical structure, with 

 an outer cellular envelope inclosing a 

 dense mass of very small cubical cells 

 in which are developed the sperms. The 

 sperms are minute elongated or slightly 

 coiled protoplasts, with a pair of cilia at 

 one end. The mature antheridia only dis- 

 charge their sperms when wet, as after 

 heavy rains or dews, and the sperms then 

 FIG. 244. Thearchego- swim about in the moisture. At these 

 nium of a liverwort times fa Q plants are practically leading 



.. ,. ,., ,, , i 

 an aquatic life like their algal ancestors, 



"d the development of motile sperms 

 receptacle (Fig. 251). The in these land plants shows clearly that 

 they must have come from forms with 



(Marchantia) 



archegonium, while the aquatic life habits. 



neck n contains a row of ,m 7 T 



canal cells which break Tlie egg-producing organ, or archego- 

 down into mucilage as the nium. The female organ is called an 



archegonium matures. , . T , . a , , , .. n A 4 . 



arcliegomum. It is flask-shaped (r ig. ^44), 



and the outer cellular envelope incloses at maturity a row of cells. 

 The cell situated in the enlarged portion of the archegonium 



