LIFE HISTORY OF A LIVERWORT 
223 
previously studied. Except for the sterile wall-cells, all 
the cells formed by the successive divisions of the oopserm 
<lTC3rvy x ; ; /y^fesaA 
< 
FIG. 169. Ricciocarpus. sp., sporogonium; gam, tissue of gametophyte. 
FIG. 170. Life cycle of Ricciocarpus. (After Cardiff.) 
become spore-mother-cells, each of which, by the tetrad- 
division, gives rise to four spores. Meanwhile the wall- 
