TISSUES OF ANGIOSPERMS. 



441 



into the second leaf i.e., the leaf at the summit of the in- 

 ternode under consideration ; the bundles 

 I, m, n descend from the leaf next above, 

 and p and q from the one still higher. 



541. We may get a clearer idea of the 

 mutual relations of the bundles if we con- 

 ceive the bundle-cylinder to be split down 

 on one side, and spread out upon a plane. 



In Fig. 317 we have such a diagrammatic Fig. sip. Cross-sec- 

 tion of the next to the 

 representation of the arrangement of the ] wer internode of Fig. 



, l ,, i .i. * oi I j- 315,showingthearrange- 



bundles in the stem of ktacliys anyusti- ment of the bundles, the 



/. 7 . TT i i j 11 lettering as in Fig. 315. 



joints. Here each leaf sends down two After Najreii. 



bundles, which pass through two internodes and then unite 

 2 with other descending bundles at 



\ their middle points. The fibro- 



J^ J^ vascular cylinder is thus compos- 



ed when complete of repeatedly 

 branching bundles. A cross-sec- 

 tion (Fig. 318) through the stem 

 at some distance above the lower 

 leaves in Fig. 317 

 shows that each 

 internode c o n - 

 tains bundles 

 from two pairs of 

 leaves i.e., those 

 at its summit and 

 those at the sum- 

 mit of the one 

 above. In Fig. 

 318 the pairs of 

 bundles marked c and d descend 

 from the leaves c and d, while 

 those marked e and/ pass down 

 from the leaves 0:10 internode 



Fiff. 317. Diagram showing the ar- higher up. 

 rangement of the fibre-vascular bun- T ., , , -, -,. 



dies in staohys angmtif oiws. a, 6, In a similarly constructed dia- 

 gram of the fibre-vascular cylin- 



Figr. 318. Cross- 

 section of the next 

 to the lower inter- 

 node in Fig. 31", 

 showing the disposi- 

 tion of the bundles, 

 the lettering ad in 

 Fig. 317. After Nft- 

 gefi. 



projected upon a series of transverse and vertical lines to 



