BRYOPHYTES 
305 
globular body (Figs. 277, 278). A section through this 
body shows it to consist of a single layer of cells, which 
forms the wall of the antheridium, and 
within this a compact mass of small 
cubical (square in section) cells, within 
each one of which there is formed a 
single sperm (Fig. 278). The sperm is 
a very small cell with two long cilia 
(Fig. 277). These small biciliate sperms 
are one of the distinguishing marks 
of the Bryophytes. When the mature 
antheridia are wet they are ruptured at 
the apex and discharge their contents 
(Fig. 277), and the sperms escaping 
swim actively about. 
199. The archegonium. This name 
is given to the female sex organ, which 
is a many-celled structure, shaped like 
a flask (Figs. 277, 287). The neck of 
the flask is more or less elongated, and 
within the bulbous base (venter] the single egg is organized. 
To this neck the swimming sperms are attracted, enter 
and pass down it, one of them fuses with the egg, and this 
act of fertilization results in an oospore. 
200. Germination of the oospore. The oospore in Bryo- 
phytes is not a resting spore, but germinates immediately 
by cell division, forming the sporophyte embryo, which 
presently develops into the mature sporophyte (Fig. 279, A). 
The lower part of the embryo develops downward into the 
gametophore, forming the foot, which penetrates and ob- 
tains a firm anchorage in the gametophore (Fig. 279, B, C). 
The upper part of the embryo develops upward, organizing 
the seta and capsule. In true Mosses, when the embryo 
becomes too large for the venter of the archegonium in 
which it is developing, the archegonium is broken near the 
base of the venter and is carried upward perched on the top 
FIG. 278. Antheridium of 
a liverwort in section, 
showing single layer 
of wall cells surround- 
ing the mass of moth- 
er cells. After STRAS- 
BURGER. 
