128 



MINUTE STRUCTUHE OF THE STEM. 



ture (see 390) ; but in Fig. 103 the bundles are closed (see 315), 



and incapable of 

 further increase in 

 thickness. Hence 

 any further growth 

 in thickness of the 

 stem shown in 

 Fig. 103 must be 

 by the intercala- 

 tion of new bun- 

 dles. 



379. It was held 

 by Desfontaines 1 

 that the new vas- 

 cular bundles in 

 Palms originate in 



104 



1 Quoted by Mohl, 

 in The Structure of 

 the Palm-Stem (The 

 Eay Society, Reports 

 and Papers on Bot- 

 any; London, 1849). 



Another illustration 

 of the arrangement of 

 fibre-vascular bundles 

 is here given : - 



The stem of the Vi- 

 tis vin il era is usually 

 regarded as sympo- 

 dial; that is, it is com- 

 posed of internodes 

 belonging to different 

 axes (see vol. i. pp. 54 

 and 154). In this 

 species of grapevine 

 two leaves in succes- 

 sion have a tendril on 

 the opposite side, then 

 follows a leaf without 

 any tendril, next the 

 sequence of two with 



FIG. 104. Diagrammatic projection, showing the disposition of the fibro- vascular bun- 

 dles in a leafy shoot of Vitis viuifera. Each leaf has five fascicles, which are unsymnu- 

 trically arranged : a, />, c, d, c ; h, i, /,', /, ? ,- o, p, q, r, s ; u, r, ii\ ., // ; o, j8, -y, 6, e ; ij, , 

 0, i, K. Each tendril lias three fibro- vascular bundles passing in from the stem, g, t, z; 

 the axillary buds have also three, /and n. (Nageli.) 



