270 



STRUCTURE OF LIVERWORTS 



in close contact with the soil {e.g. the common Liverworts Pellia, 

 Fig. 146, B, and Marcliantia, Fig. 146, E). At the base of the 

 notch situated at the tip of each lobe of the thallus lies the 

 growing point (Fig. 146, D, g.p.), which commonly consists of a 

 marginal row of cells. The middle part of each segment is 



Fig. 146. — Various thalloid Liverworts. A, Small part of the thallus of 

 Fegatella, seen from the under-surface, showing the dense weft of 

 rhizoids. B, Group of thalli of Pellia (ordinary form), one with a 

 young sporogonium (s.). C, Pellia, form characteristic of xcry wet 

 habitats. D, Thallus of Fegatella from the upper surface, showing 

 the antheridial discs (a.). E-G, Marchantia. showing respectively 

 gemma-cups (g.), antheridial head, I', and archegonial head, G. g.p., 

 growing point ; m., midrib. (All figures approximately natural size.) 



generally somewhat thickened like, a midrib (Fig. 146, in.), 

 and projects to a more or less marked extent on the lower side 

 of the thallus. Water and nutrient salts are absorbed by 

 numerous fine thin-walled unicellular hairs (rhizoids, Fig. 146, A ; 

 Fig. 152, r.), which grow out into the soil from the lower surface 



