246 PHYLUM VIII. BRYOPHYTA 
On germination the egies produce gametophytes like 
the originals. 
430. The very conspicuous Great Liverwort (Mar- 
chantia) is common on moist ground and is frequently 
abundant in green houses. Its gametophyte is a large, 
flat, branching, thalloid plant with a distinct midrib. 
Its epidermis is pierced with circular, many-celled 
“stomata”? which open into large 
air cavities supplied with many 
| green cells. Here and there on the 
upper surface are cups containing 
hairs whose terminal cells develop 
Fic. | 120.—Marchantia, into green masses (brood masses, or 
gemmae) which fall off and quickly 
develop into new gametophytes. This is thus an asex- 
ual mode of reproduction, and these brood masses take 
the place of the zoospores, tetraspores, 
and conidia of lower plants. ? 
431. The antherids are confined to par- 
ticular portions of the gametophyte (an- 
theridial disks) which are raised on short i: 
stalks. Here they are sunken in the sur- "6,217 March- 
face and they and the sperms resemble 
those of Riccia and Anthoceros. 
432. The archegones are also confined to particular 
portions of the gametophyte (known as “receptacles” 
but really lobed disks) which are raised 
{ on more or less elongated stalks (arche- 
} gonial branches). The archegones are 
j dependent from the under side of the re- 
= JY ceptacle. When fertilized the egg de- 
pen eherek- velops into a globose, shortly stalked 
sporophyte containing spores and elon- 
gated sterile cells, the “elaters,’’ whose walls are spirally 
Tyee Tee 
