LIFE HISTORY OF FERN 



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attached to prothallus with well-developed first leaf and root ; 

 St., stem (still small). G, pinnule of fern leaf from below showing 

 seven sori [so.) and ripe sporangia {spg.) protruding from below 

 membrane of sorus. H, single sporangium opening to set free 

 spores {sp.). I, spore {sp.) germinated to form pi'othallus ; rh., 

 rhizoids; a, apical cell. 



