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APPLIED BIOLOGY 



taining wood-tubes and sieve-tubes, which act as in seed- 

 plants in conducting fluids up and down the stem. Also, as 

 in the higher plants, the vascular bundles extend into the 

 veining of the leaf, thus providing the leaf with a water- 



FIG. 70. Aspidium fern. A, part of underground stem with three young 

 leaves (a), and parts of three mature leaves, one with numerous clusters 

 of spore-cases. B, section transverse of leaflet with cluster of spore-cases 

 (c) on lower side and covered by a cap (6). C, under side of a leaflet 

 with seven clusters of spore-cases. (From Strasburger.) 



supply system and a means of transferring elaborated foods 

 to cells of the stem and roots. The general form and struc- 

 ture of the leaves reminds one of those of seed-plants. The 

 leaves of many ferns are much divided and resemble com- 

 pound leaves of seed-plants. 



The one most striking difference as compared with the 



