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PLANTS, THE FOOD OF ANIMALS 



FIG. 49. Development of a fern (Aspidium) sporangium, a, The young spor- 

 angium-forming cell just divided from its parent epidermis cell; b, c, d, e, /, 

 different aspects of the dividing cells of the spore capsule; g, origin of the tapetal 

 cells and formation of the spore-producing cell or archesporium (ar); h, increase 

 of the tapetal cells (/) and formation of the spore mother cells; i, j, k, further 

 stages in the development of the sporangium; an, annulus; pd, pedicel. (From 

 Sedgwick and Wilson.) 



