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 multipHcation 

 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 gametoph}te. 



187. Life-cycle of Sphagnum. — The life-cycle of sphag- 

 num maj' be summarized as follows: 



OUTLINE OF LIFE HISTORY OF SPHAGNUM 



Sphagnum-plant {gametophytc) 



I 



.T T" 



Antheridial branch Archegonial branch 



i i 



Antheridia Archegonia 



I I 



Sperm (male gamete) Egg (female gamete) 



FcrtUizaiion 



Oosperm (zygote) 



a 



Embrvo 



li 



Mature Sporophyte (mature zygote) 



a 



Sporangium 

 S pore-motlier-cell 



n 



Reduction 



i 

 Spore Spore Spore Spore 



i 



Protonema 



i 



Thallus 



i 



Sphagnum-plant [gjiiuiopliyU') 



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

 num may be diagrammatically represented as follows: 



