BRYOPHYTES 
95 
Sporophyte. The fertilized egg (fig. 220) produces the sporophyte 
(called sporogonium in the bryophytes), which when mature is a spherical 
body, consisting of a wall layer of sterile cells investing a mass of spo- 
rogenous cells (figs. 221- 
226). In producing this 
body the egg by succes- 
sive divisions usually 
first becomes a sphere 
of eight cells (octants). 
Then periclinal (parallel 
with the surface) walls 
cut off an outer layer of 
ce\\?>(amphUheciuni) that 
forms the wall of the 
sporophyte. The group 
of inner cells is the 
endolhecium, which by 
successive divisions pro- 
duces a mass of sporog- 
enous tissue. The cells 
produced by the last 
divisions of the sporog- 
enous tissue are the spore 
mother cells, each of 
which produces a tetrad 
of spores (fig. 226), dur- FIGS. 205-211. Riccia: development of the an- 
ing which process the theridium; 205, first division of the superficial initial 
reduction in the number cel1 ' * e P rotrudin g ceU * f ve r f> J the antheridium; 
206, first transverse division of the anthendial cell; 
of chromosomes OCCUrs. 207, further transverse divisions; 208, the beginning of 
The mature sporophyte, vertical walls; 209, completion of periclinal walls sepa- 
therefore is simplv a rating the wal1 of the antneridium from the spermatog- 
enous cells; 210, an almost mature antheridium, show- 
spore case. The venter j ng t h e short stalk, the wall, and the mass of cubical 
of the archegonium spermatogenous cells in conspicuous blocks; 211, a 
grows also forming a s P erm > sbowin S the biciliate bryophytic type (body of 
sperm black; adjacent light mass is cytoplasm dragged 
special investing struc- O ut of the mother ceU). 
ture, the calyptra (fig. 
225). Finally the wall layer of the sporophyte and the layers of the 
calyptra become disorganized, and the spores are free in the archegonial 
chamber. The spores upon germination produce the gametophyte body. 
210 
