HEPATIC^. 



345 



and by the repeated division of tlieir apical cells produce 

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



Fig. 2B1.— Male organs of Marchantia polymorpM. A, a portion of the thallus, t, 

 witli two ascending branches bearing the antheriaial 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 thallua ; h^ root-hairs ; 6, leaf-like bod- 

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

 two spermaiozoids. Variously magnified. I> X 800. — After Sachs. 



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

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



Fig. 233.— "DevelopnifTit of the antheridia of Mccia glauca. A, loTiffitndinal section 

 through the apex of the tliallu- : s. apical cell of the thallus : A, scaie-like leaves, in 

 section; a, a very young antheridium; a', an older jintheridium, eurronnded by a 

 growth of thallus tissue, w. B, a young antheridium, <?, overarched hy a growth oi 

 The thallus. C, an older antheridium, in longitudinal section, x 500. — After 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. 



