96 



MORPHOLOGY 



Conclusions: — The life history of the Ricciaceae suggests certain 

 important conclusions. The sporophyte is the simplest known among 



Figs. 212—220. — Riccia: development of the archegonium; 212, first division of the 

 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 jacket 

 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 

 canal cells and the ventral cell (lowest and largest) ; 218, division of the ventral cell to 

 produce the ventral canal cell and the eg^;; 219, a completed archegonium, showing neck 

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

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



