TISSUES OF ANG10 SPERMS. 



441 



Fig. 316. Cross-sec- 

 tiou of the next to the 

 lower internode of Fig. 

 315,showingthe arrange- 

 ment of the bundles, the 

 lettering as in Fig. 315. 

 After Nageli. 



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



ternofle under consideration ; the bundles 



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



and j9 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 



representation of the arrangement of the 



bundles in the stem of Stachys anyusti- 



folius. Here each leaf sends down two 



bundles, which pass through two internodes and then unite 

 with other descending bundles at 

 their middle points. The fibro- 

 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 gel', 

 bundles marked c and d descend 

 from the leaves c and d, while 

 those marked e and/ pass down 

 from the leaves one internode 



Fig:. 317. Diagram showing the ar- higher up. 

 iingernent of tho fibro-vascular bun- T M i n -,- 



dies in stadiys antfuttifoiiw. a, b, In a similarly constructed dia- 



/" \ 



i 



_ 318. Cross- 

 tion of the next 

 to the lower inter- 

 node in Fig. 317, 

 showing the disposi- 

 tion of the bundles, 

 the lettering as in 

 " 317.-After Nil 



</, c, 



the points 



from which' the"' successive^ptiirs" 1 ,? gram of the fibro-vascular cylin- 



leave.RprtuB.-AfterOTgdl. ^ Qf ^^ ^^ (]? . ^ 



projected upon a series of transverse and vertical lines to 



