PHANEROGAMIA. 
221 
468. The tissues of the Gymnosperms are individually 
but little higher than those of the Fernworts, but in their 
Fic. 125.—Diagrammatic cross-sections of stems, showing the fibro-vascular 
bundles, fc, of w 
ich x is the woody side and p the softer or bark side; 3, b, b, 
bast- fibres: R, M, the fundamental tissues of the stem, of which & (the rind) i is 
the cortical and 'M the medullary portion, or pith; ic, a belt of cambium which 
extends from bundle to bundle. 
arrangement they show great and 
important differences. The fibro- 
vascular bundles are of the col- 
lateral form, and are so placed in 
the stem that the harder and more 
woody side is nearer the centre of 
the stem, while the softer side is 
always nearer to the surface (Fig. 
125, A). The inner part of the 
bundles is composed mostly of long, 
large cells, the tracheids, which 
have the well-known characteristic 
bordered pits (Fig. 126). The outer 
part contains, besides other tissues, 
a little fibrous tissue (bast-fibres). 
Between these two halves of the 
bundles there is a thin layer of 
growing cells (cambium) which is 
continuous with a layer between 
A and B). 
Seige 
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Fia. 126.—Longitudinal sec- 
tion of wood of a Pine (Pinus 
sylvestris). Bordered pits, t’,l’, 
t’’; a-e, parts of six tracheids; 
sl, large pits, where medullary 
rays touch tracheids. Magni- 
fied 325 times. 
the bundles (Fig. 125, 
At this stage the stem is composed of an inner 
