THE FIBHO-VASaULAR 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 



Mg. 98.— Part of the croBS-section of an old root of Adiantum Moritzlanvm, h, h. 

 bairBot'the root surface; m,k, bundle sheath (endodennis) ; between A and K.pa- 

 , pericambium ; pr^ a plate of tracheary tiBsue, which is bonndea on 



Tenoh^a ; pc, . 



each side by sieve tissue. 



X 885.— After De Bary. 



bundle of the rhizome of Polypodium vulgare. Here the 

 central 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 



