LIFE HISTORY OF A LIVERWORT 



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previously studied. Except for the sterile wall-cells, all 

 the cells formed by the successive divisions of the oopserm 





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Fig. i69.~Ricciocarpus. sp., sporogonium; gam, tissue of gametophyte. 



Fig. 170.— Life cycle of Ricciocarpus. (After Cardiflf.) 



become spore-mother-cells, each of which, by the tetrad- 

 division, gives rise to four spores. Meanwhile the wall- 



