HEPATIC^!. 



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 polymorpha. 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, antheridium 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. (7, a nearly ripe antheridium ; at, 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 

 B /*r>v n A -'"- 



Pig. 232.-Development of the antheridia of Riccla fflauca. A, longitudinal section 

 through the npex of the thallus : , apical cell of the thallns : b, scale-like leaves, in 

 section- . a very young antheridium; a', an okkr jintheridinm. surrounded by a 

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

 the thallus. 6", an older antheridium, in longitudinal section, x 500. After Hof- 



simpler than those just described ; in the Jungermanniaceas, 

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

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



