no 



BOTANY. 



differentiate J, being composed of parenchyma and poorly 

 developed sieve tubes {s, Pig. 97). The whole bundle is sur- 

 rounded, as in Pteris aquilina, by a bundle sheath {u, Pig. 

 97). In the outer part of the mass of scalariform tissue are 

 a few narrow spiral vessels {sp, sp, Pig. 97), but they are 

 not sufficiently numerous to constitute a ring or layer. 

 138. — In the root of Adiantum Moritzianum the bundle 



consists of a cen- 

 tral plate of tra- 

 cheary tissue {pr, 

 Pig. 98), with a 

 mass of sieve 

 tissue on each 

 side of but not 

 quite enveloping 

 it. Next outside 

 of this is a layer 

 of active paren- 

 chyma, the peri- 

 cambium {pc, 

 Fig. 98), and sur- 

 rounding the 

 whole is a poorly 

 developed bundle 

 sheath (u, Pig. 

 98). 



139. — In the 

 stem of Equise- 



rig. i)9.— Transverse section of a flbro-vascnlar bundle of , , , •, 



IHquUPivmpalvstrf'. r, /, ringed vesseli? on the border of a tUlf}l pCtCUSlTe IC 



large intercellular canal; », sieve tissue; g,g, groups of • j. ooov is 



annul.'ir and reticulated vessels; w, the so-called general ^° xiuu au caoj tio 



bundle sheath, which surrounds all the bundles ; i, i, axial ;„ j-t,„ ■fnrpo-nino' 



aircaniJs; x , x, fragments of the ruptured cells. X 146. ^"^ ''"*' luiegumg 



-After De Buiy. cascs to mark the 



limits of the bundles, which are arranged in a circle about 

 the axis.* On the axial side of each bundle there are at 

 first a few spiral and annular vessels, most of which, 

 along with a considerable amount of parenchyma, are 



* In Equisetum limosum, however, there Is a bundle sheath about 

 each bundle, consequently there is in that species no difficulty as to 

 the limits of the bundle. 



