THE BRYOPHYTES 423 
ALTERATION OF GENERATIONS.—In the life history of Mar- 
chantia there are two distinct generations. The gametophytes 
bear the sex organs in which gametes (sperm and egg) are pro- 
duced. The sperm unites with the egg forming an oospore. 
SSS ue 
Fic. 314.—Marchantia polymorpha. 1. Thalloid body of Female Gametophyte - 
with archegonial receptacles (archegoniophores) in successive stages of develop- 
ment, a1, a2, b,c, d,e,f. 2,3, Upper and under views of archegoniophore when the 
sporophytes are ripe. 4, 5, Stages in the development of the sporophyte. 6, 
Young sporophyte enclosed by a perigynium. 7, Mature sporophyte shedding 
spores. 8, Elater and spores. 9, Surface view of cells from wall of capsule. 
(From Small after Kny.) 
The oospore develops into a sporophyte which forms spores. 
Each spore may develop into a gametophyte. 
male gametophyte—sperm raha sporophyte— 
female gametophyte—egg eee 
male gametophyte 
steed female gametophyte 
