XI. HEPATIC^. 



937 



Monodea Forsteri, 

 TJnivalved sporangium. 



Metzgeria furccUa. 



Fragment of sporangium, bearing 



elaters with simple spores. 



AnlJioceros. 



Dehiscent antheridium 



(mag.). (Roze.) 



Monodea Forsteri, 

 Portion of frond and uni- 

 locular sporangium (mag.). 



ArUhoceros. 

 Section of frond, showing the 

 antheridia (mag.). (Roze.) 



Riccia Bischo_0i 

 (mag.). 



Riccia Bischoffii. 



Section of a portion of frond, showing 



the archegonia (mag.). 



upper part of tlie membranous sac or calyptra ; the base of tbe sac persists, and 

 forms a sheatb (vaginula) around the base of the pedicel. 



The SPOBAN(iiXJM usually opens in four valves, very rarely more, or breaks 

 irregularly {Fossomhromia). In Anthoceros it is traversed by a central columella. It 

 contains : — 1st, very elongated cells, usually fusiform, sometimes truncate {Frullania, 

 Lejeunia), which, are usually free at the dehiscence of the sporangium, but may be 

 attached to the tips of the valves {Frullania, Lejeunia, Aneura, Metzgeria), or 

 partially adhere to the bottom of the sporangium {Pellia) ; these ceUs, called 

 elaters, contain, pressed against their wall, a small dark-coloured ribbon in a single 

 {Aneura) or double' spiral ; the elaters, by their twisting movement, serve to dis- 

 seminate the spores : — 2nd, spheroid mother-cells, within each of which are developed 

 four spores, which are set free by the absorption of the mother-cells. In germi- 

 nation the spore emits a small cellular prothallus, which reproduces the plant. 



HepaticecB, besides sexual reproduction, can be propagated, like Mosses, by buds, 

 or propagula, which appear oh the surface or margins of the frond. They are 

 cellular, rounded, polymorphous, sometimes tolerably large, and analogous to bulbils. 

 In some cases {Blasia), these propagula occupy ovoid pouches, hollowed in the nerve 

 and top of the frond. One rather curious example of this mode of propagation is 

 met with in the tribe of Marchantiece. On the surface of the fronds of some species 

 of Marchantia are seen foliaceous membranous cups, with entire or elegantly fringed 

 margins ; at the bottom of these cups are ovoid or lenticular bodies, composed of 

 granular cells ; these little bodies are at first fixed to. the bottom of the cup by a 



