224 STRUCTURE AND LIFE HISTORIES 



cells become disorganized and their substance goes to nour- 

 ish the spores. By this time the cells of the inner layer 

 of the venter have also become disorganized and their sub- 

 stance, in like manner, is absorbed by the spores (Fig. 169). 

 Thus the tissue of the gametophyte serves as nourish- 

 ment for the developing, primitive sporophyte. The phe- 

 nomenon of an embryo developing into a mature sporophyte 

 does not appear in Riccia. As we descend the scale of plant 

 life we find the sporophyte increasingly simpler; and this 

 simplicity consists in the diminution of the amount of 

 sterile tissue. 



204. Life History of Riccia. — The life history of Riccia 

 is shown in outline as follows, and diagrammatically in 

 Fig. 170. Carefully compare this history with that of 

 Anthoceros. 



OUTLINE OF LIFE HISTORY OF RICCU 

 Riccia-plant {gametophyte) 



Oosperm (zygote) 



Cell-divisions 



Sporophyte (transient spore-case) 



44- 



S pore-mother-cclls 



\r X^ X- X ] Reduction 



Spore Spore Spore Spore 



i 



Protonema 



i 



Riccia-plant {gametophyte) 



