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 
is practically eliminated. As we descend the scale of plant 
life we find the sporophyte becoming simpler and 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 RICCIA 
Riccia-plant (gametophyte) 
4 
Oosperm (zygote) 
Ar Ar 
Cell-divisions 
44 
Sporophyte (transient spore-case) 
44 
Spore-mother-cells 
4 4 4- I / 
Spore Spore Spore Spore 
4 
Protonema 
4 
Riccia-plant (gametophyte) 
