HEPATIC^. 



345 



and by the repeated division of their apical cells produce 

 upon each a little flattened mass of cells, the gemma. These 



Fig. 231. Male organs of Marchantia polymarpha. A, a portion of the thallus, t, 

 with two ascending branches bearing the antheridial receptacles, hu. B, vertical sec- 

 tion through young antheridial receptacle, hu ; a, anthendium enclosed in a cavity 

 which has a narrow opening, o; t. portion of thallus ; A, root-hairs ; b, leaf-like bod- 

 ies seen in section. C, a nearly ripe antheridium ; st, its pedicel ; w, the wall. D, 

 two spermatozoids. Variously magnified. D X 800. After Sachs. 



gemmae, when full-grown, fall to the ground, and grow di- 

 rectly into new plants. In some cases the gemmae are much 



A 



Fig. 232. Developmpnt of the antheridia of Kiccia glauca. A, longitudinal section 

 through the apex of tho thallu* : . apical cell of the thallus ; b, scale-like leaves, in 

 section; a, a very young antheridium; a', an older antheridinm. surrounded hy a 

 growth of thallus tissue, w. B, a young antheridium, a, overarched by n growth 01 

 the thallus. U, an older antheridium, in longitudinitl section, x BOO. Alter Hof- 

 meister. 



simpler than those just described ; in the Jungermanniaceae, 

 for example, they consist of a few cells which are spontane- 

 ously detached from the tissues in the margins of the leaves. 



