LIFE HISTORY OF A MOSS 203 
protonema. At the tips of each of these threads a thallus 
may also form, and in this way vegetative multiplication 
is brought about. From each thallus arises an upright 
leafy branch the sphagnum-plant described above. The 
reader has already recognized that this complex phase of 
sphagnum is the gametophyte. 
187. Life-cycle of Sphagnum. The life-cycle of sphag- 
num may be summarized as follows: 
OUTLINE OF LIFE HISTORY OF SPHAGNUM 
Sphagnum-plant (gametophyte) 
4 + 
Antheridial branch Archegonial branch 
Antheridia Archegonia 
Sperm (male gamete) Egg (female gamete) 
Fertilization 
^s ^ 
Oosperm (zygote) 
Embryo 
Mature Sporophyte (mature zygote) 
Sporangium 
n 
Spore-mother-cell 
} Reduction 
Spore Spore Spore Spore 
Protonema 
4^ 
Thallus 
Sphagnum-plant (gametophyte) 
188. Diagram of Life-cycle. The life-cycle of Sphag- 
num may be diagrammatically represented as follows: 
