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) 



'* t 



Antheridial branch Archegonial branch 



4 4 



Antheridia Archegonia 



4 4 



Sperm (male gamete) Egg (female gamete) 



Fertilization 



^ ^ 



Oosperm (zygote) 

 Embryo 



44 



Mature Sporophyte (mature zygote) 



4 4- 



Sporangium 

 Spore-mother-cell 



Reduction 



I 1 I I 



Spore Spore Spore Spore 

 Protonema 



4 



Thallus 



4 



Sphagnum-plant (gametophyte) 



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

 num may be diagrammatically represented as follows: 



