9 6 



MORPHOLOGY 



Conclusions. — The life history of the Ricciaeeae suggests certain 

 important conclusions. The sporophyte is the simplest known among 



Figs. 212-220. — Riccia: development of the archegonium ; 212, first division of X\\z 

 superficial initial cell, the protruding cell to give rise to the archegonium ; 213, the 

 three vertical walls (two seen in section) investing an inner cell, the relation between 

 the three walls being shown in the cross section, 214; 215, further development of j.ic k. t 

 cells, completely investing a central cell (first cell of axial row); 216, first division of 

 central cell into primary neck canal cell (upper one) and primary ventral cell; 

 217, further development of the jacket and axial row, the latter showing the four neck 

 (anal (ills and the ventral cell (lowest and largest); 218, division of the ventral cell to 

 produce the ventral canal cell and the eg-j; 2 to, a completed archegonium, showing neck 

 and venter, and the axial row, consisting of four neck canal cells, a ventral (anal cell, 

 and an egg; 220, fertilization, showing male and female nuclei fusing in the egg. 



