LETTER yi. 



51 



trunk. It will be seen that there is an entire absence of 

 the concentric circles both of wood and bark so charac- 

 teristic of the Exogenous stem, and that instead of this 

 there is a mass of cellular tissue inclosed within a single 

 cortical ring of somewhat irre- 

 gular outline, and pierced here 

 and there throughout, but most 

 abundantly towards the circum- 

 ference, by bundles of woody 

 fibre. Fig. 9 is a mere plan^^--- 

 of the upper part of the palm- ^ 

 trunk, showing the manner in 

 which the woody fibres pass 

 downwards from the leaves in 

 curves or arches towards the 

 circumference of the stem, in 

 the cortical integument of which 

 they lose themselves. 



3. The trunk of the Palm-tree, it may be observed, 

 does not increase in diameter by age, as does that of 

 the Exogen. It increases only in height, and that by 



* Fig. 9. — a h, The lower, fully developed, part of the stem; c c,- 

 External firmer portion of the stem, formed by the closer course of 

 the woody fibres ; d d d, Woody fibres running as far as the cica- 

 trices of leaves that have died ofp; e e e e e, Leaves in the bud, in 

 the order in which they are developed, with the woody fibres belong- 

 ing to them ; / /, The latest-formed leaves. All that is cut off by 

 the dotted line oc y, above the stem, has originated at the same time 

 with the lowest pair of leaves (e e). — See Schleiden's Principles of 

 Scientific Botan'^, p. 246. 



