50 MINUTE MARVELS OF NATURE 



wort." Here we see a ring of comparatively 

 large, open gaps in the tissue of cells ; and most 

 aquatic plants possess these air cavities among 

 their tissues, serving as buoys to the plant-stem. 



Fig. 33. The structure of a club-moss stem 



The common water-lilies are familiar examples ; 

 while another beautiful example from the stem of 

 a familiar pond and ditch plant called " marestail " 

 is shown in Fig. 32. Perhaps lady readers m'ght 

 profitably use this as a pattern for fancy work, a'nd 

 so obtain a new design "direct from Nature." 

 Another curious form of stem structure is shown 



