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 thal- 

 lophytes are, with very few exceptions, 

 one-celled. The conspicuous exceptions 

 are the plurilocular sexual organs of the 

 lower brown' algre (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. The archego- swim about in the moisture. At these 



nium of a liverwort t i mes t j ie pi an t s are practically leading 



(Marchantia) ,. ,.,, v , ,-. . , -, 



an aquatic me like their algal ancestors, 



Thearchegoniainthisgenus d t} developmen t of motile sperms 

 hang down from a special 



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



large egg is shown in ,1 -i f f -.i 



the swollen base of the the y must have COme fr0m foi>lnS Wlth 



archegonium, while the aquatic life habits. 



neck n contains a row of ,777 7 7 



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



down into mucilage as the nw/,m. The female organ is called 



archegonium matures. 



mum. me lemaie organ is called an 

 archegonium. It is flask-shaped (Fig. 244), 



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



The cell situated hi the enlarged portion of the archegonium 



