CHAP. II. 
STEM. 
53 
The Stem has received many names; such as caudex 
ascendens, caudex intermedins, culmns, stipes, truncus, and truncus 
ascendens. It always consists of bundles of vascular and woody 
tissue, embedded in cellular substance in various ways, and 
the whole enclosed within a cuticle. The manner in which 
these parts are arranged with respect to each other will be ex- 
plained hereafter. The more immediate subject of consideration 
must be the parts that are common to all stems. 
1. Of its Parts. 
Where the stem and root, or the ascending and descending 
axes diverge, there commences in many plants a difference 
of anatomical structure, and in all a very essential physiolo- 
gical dissimilarity ; as will be hereafter seen. This portion of 
the axis is called the neck or collum, {coarcture of Grew, nceud 
vital oi Lamarck, limes communis, or fundus plantce, of Jungius,) 
and has been thought by some to be the seat of vegetable 
vitality ; an erroneous idea, of which more will be said in the 
next book. At first it is a space that w^e have no difficulty in 
distinguishing, so long as the embryo, or young plant, has 
not undergone any considerable change; but in process of 
time it is externally obliterated ; so that in trees of a few years' 
growth its existence becomes a matter of theory, instead of 
being actually evident to our senses. 
Immediately consequent upon the growth of a plant is the 
formation of leaves. The point of the stem from whence these 
arise is called the node (geniculum, Jungius), and the space 
between two nodes is called an inter node (merithallus, Du Petit 
Thouars). In internodes the arrangement of the vascular and 
woody tissue, of whatever nature it may be, of which they are 
composed, is nearly parallel, or, at least, experiences no hori- 
zontal interruption. At the nodes, on the contrary, vessels 
are sent off horizontally into the leaf; the general develope- 
ment of the axis is momentarily arrested while this horizontal 
communication is effecting, and all the tissue is more or less 
contracted. In many plants this contraction, although it 
always exists, is scarcely appreciable ; but in others it takes 
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