TISSUES OF ANQI0SPERM8. 



441 



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

 ternode under consideration ; the bundles 

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

 and^ 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 Fiff. 317 we have such a diagrammatic ^.I'ig- 3i6. -crosB-sec- 



o ° tioii of the next to the 



representation of the arransrement of the '"wer mtemode of Fig. 



■*■ ° 3I5,8howingtliearrange- 



" " ■ ■" tlie 



bundles in the stem of Stachys angusti- ment of the bundles, 



/. 7 . T-r 1 1 J! T n J lettering as in Fig. 315. 



folius. Here each leal sends down two — AfterTstageii. 



bundles, which pass through two internodes and then unite 



with other descending bundles at 

 their middle points. The fibro- 

 Tascular 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 piairs 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 one internode 



Fig. 317.— Diagram showing the ar- higher Up. 

 Tangement of the flbro-vascHlar bun- t . ., , ,-,-,■ 



dies in Stachys anguttifoiius. a, 6, In a Similarly Constructed dia- 

 ftoni''w'hich'the'''suc7e8sive' pfira^o? gram of the fibro-vascular cylin- 



leaves spring-After Nageli. ^^^ ^f j^^^-^ ^^^^^ (j,jg_ g-^g^ 



projected upon a series of transverse and vertical lines to 



Fig. 318. — Cross- 

 section of the next 

 to the lower inter- 

 node in Fig. 317, 

 showing the dispobi- 

 tion of the bundles, 

 the lettering as in 

 Fig. 317.— After Na- 

 geli. 



