LIVERWORTS 169 
the back of the thallus (Fig. 163). These bodies are round 
and flat (biscuit-shaped) and many-celled, and falling out 
of the cup they start new thallus bodies. 
Although the thallus body produces no spores, it does 
produce sex-organs. In Marchantia, long, erect, stem-like 
branches arise from the thallus, bearing at their summits 
conspicuous disks that contain the sex-organs. The disks 
containing antheridia are lobed or scalloped (Fig. 163); 
while those containing the egg-producing organs are star- 
shaped (Fig. 165). The two kinds 
of disks are not found on the 
same plant. 
93. The antheridium. — The 
sperm-producing organ is called 
an antheridium, but it is very 
different from the antheridia of 
the Thallophytes. Instead of be- 
ing a single cell, it is a stalked, 
club-shaped or globular, many- 
celled structure (Fig. 164). A 
single layer of cells forms the 
covering, and within it there is 
a closely packed mass of small py, 164.—1farchantia: antheridi- 
cells, each one of which pro- siete two} ispermays>a\ iter 
duces a sperm. The sperm is 
a very small cell with two long cilia, and these small 
biciliate sperms are one of the distinguishing features of the 
hverworts and their allies. 
94. The archegonium.—The egg-producing organ is 
called the archegonvum, and it is very different from the 
odgonium of the Thallophytes. Instead of being a single 
cell, it is a many-celled structure, shaped like a flask with 
a long neck, and within the bulbous base the single egg is 
formed (Fig. 165, B, and Fig. 166). To this neck the 
swimming sperms are attracted; they enter and pass down 
