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 Sphagnxim. — The life-cycle of sphag- 

 num may be summarized as follows: 



OUTLINE OF LIFE HISTORY OF SPHAGNUM 

 Sphagnum-plant {gametophyte) 



— i ^ 



T T 



Anthericlial branch Archegonial branch 



i 4- 



Antheridia Archegonia 



4. I 



Sperm (male gamete) Egg (female gamete) 



Fertilization 



Oosperm (zygote) 



ii 



Embrvo 



a 



Mature Sporophyte (mature zygote) 



ii 



Sporangium 



ii 



S pore-mother-cell 



Reduction 



1 1 1 1 



Spore Spore Spore Spore 



i 



Protonema 



4- 



Thallus 



i 



Sphagnum-plant {gametophyte) 



188. Diagram of Life-cycle. — The life-cycle of Sphag- 

 num may be diagrammatically represented as follows: 



