THE BRYOl'IlYTA 



213 



DillVroiit sexes are hoi'iu' on dillci-ciit ])laiits. The t'einale uv\:;\\\ 

 consists of a number of sini])Ie ovaries ((Jogonia) (Fig. 592, c; Fig, 593, 

 ocj), grouped together in a Conceptacle. Eacli oogonium contains eight 

 Odsplieres. These oospheres are set free and are fertiHzed by motile 

 Gametes, tlie Antherozoids, which are produced in conceptacles of 

 another plant. 



The Lichens. — Most systematists now regard the Lichens as belonging 

 to the Fungi. They may be defined as Fungi parasitic on certain 

 Algae. In this form of parasitism each plant supplies some indispen- 

 sable contribution to the other, the relation being therefore called wSym- 

 l)iosis. ^riie body of the Lichen, more particularly in the larger forms, 

 is made uj) of the Fungus mycelium (Fig. 595, sh). The thallus may 



Fid. 594. Concral viow of several Lichens: A, crustaceous (Graphis); B, a portion of this samelichen 

 more highly magnifiod, showing apothecia; C, a crustaceous lichen, Pcrtusaria; D, a sub-foliaceous 

 thallus of Parmdia with numerous spore-bearing bodies, apothecia. (Sachs.) 



be large and flat, leathery and leaf-like (foliaceous. Fig. 594, D), or 

 upright and branching (fruticose), or close-clinging to the bark of 

 trees, looking like a colored stain on rocks (crustaceous, Fig. 594,^1, O- 

 Li most cases the spores are born, eight together, in little sacs called 

 Asci, which are themselves reproduced in variously colored dosed or 

 open A])()th('cia (Fig. 594, D). 



The Bryophyta. — Li this class the cons])icuous generation is the 

 gametophyte which, in the higher divisions (left hand. Fig. 59(5), 

 becomes a well-developed plant with stem and leaves. Its male repro- 

 ductive organs are the Antheridia (Fig. 597, a); its female are the 

 Archegonia. The efl'ect of reproduction is the j^roduction of an embryo, 

 which immediately germinates while upon the gametophyte, sending 

 its foot down into the tissue of the latter, and developing upward into 



