314 



BOTANY: PRINCIPLES AND PROBLEMS 



The sporogonium is sunken in the tissues of the thalkis, to which 

 it is attached at the base and from which it draws its food. In 

 the higher meml^ers of the order, as ilhistrated by the common 



Fig. 185. — Ricciocarpus natans. A, archegonium. X 200. B, antheridium. 

 X 150. C, sporophyte, contained within the remains of the archegonium, and 

 with a thin wall of its own. The spores are borne in groups of four. X 100. 



Fig. 186. — Marchantia. Thallus bearing female receptacles, in which occur 

 the archegonia. A single male or antheridial receptacle is shown separately. 



genus Marchantia (Fig. 186), the sexual organs are borne on 

 speciahzed discs, each carried up above the surface of the thallus 

 by a stalk. The sexes are separate here, some gametophytes 



