ivj THE FLOWER AND METAMORPHOSIS 59 



Fig. 11. Leaf of the male Shield-Fern (Nephrodiumfilix-mas, Eich.), 

 about one-eighth natural size, the lower part having the under 

 surface exposed. To the left a single segment, bearing the sori, 

 each covered by the kidney-shaped indusium. (After Luerssen.) 



