THK FJBRO-VASCULAR SYSTEM. 



109 



this by one of sieve tissue ; this again by fibrous tissue, and 

 so on. 



137. A similar but not identical structure is found in the 



Fig. 98. Part of the cross-section of an old root of Adiantum Maritzlanum. A, k. 

 ttainul the root surface; M,W, bundle sheath (endodermis) ; between A and w.pa 

 renchyma , pc, pericambium ; pr, a plate of tracheary tissue, which is bounded ou 

 each side by sieve tissue X 225. After De Bary. 



bundle of the rhizome of Polypodium vulgare. Here the 

 f-entral portion of the stem is made up of scalariform tissue 

 (Fig. 97, the larger, thicker-walled tissue), and this is sur- 

 rounded by a tissue which may be regarded as but partly 



