The new enterprise. (Madison, Fla.) 1901-1908, 1902-10-09
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alike. They differ greatly In size ana
shape. A second glance shows us that
the cells fan easily into groups which
form together a circle around within
the margin. The cells which make up
this band or circle are IN the growing
tree. all living cells and all active, each
in its own way. Within the limits as
signed US here we may not consider
them all, but must pay attention to the
very smallest only, those that make IN
n narrow band, marhcu = IA me figure.
II is to these tinest but ever living cells
that the tree of the forest owes il
character its long enduring vigor. Be
ing living cells, these can grow, and by
their peculiar way Of growing they ac'
complish three things-thcy lie between
bark and wood. and all the time in the
growing season those on the outside be-
come transformed into cells that make
up the cortex ultimately the bark, and
are added to its inner surface; those on
the inside are in similar way passing
over into The form Of the cells OF or
binary wood either TO form wood de
novo or 90 be added TO the wood al
ready in position; the middle cells Of
the band simply divide and divide and
so keep mp perennial supply Of cells
Of such plastic sort. Here is the secret
Of the trees endurance and Of its in.
crease in thickness, for we must re
member we are studying a cross sec.
ton Of the tree, taken anywhere, and
we must therefore conceive these tiny
,clls To form a living sheath covering
the whole tree, lying between bark and
wood. In spring we very easily pull
the bark from living trec-a willow,
tor instanCe-the separation occurring
IN the plane Of this living but proper.
tionaiely delicate cell layer. This llY.
Ing, active layer has long been named
the cambium. We shall refer to it
again.
But let us look at our section again,
We may discover still another pecul.
thrifty The border cells arrange them
selves IN groups, with slight intervals
between. The cells OF these intervals
are continuous with the large cells Of
the middle, with the pith, or mcdulla,
They may be regarded as at first part
of thc'mcdulla. They form the medul.
larry rays They build as they grow
vertical plates radiatins Outwardly
from the center Of the tree, At first
the plates are comparatively few, but
as growth proceeds the primary rays
are continually rc-cnfOrced by others,
originating indeed IN the persistent
cambum and intercalnted between
those already formed until their mum.
Der, as may be seen in any bit OF
wood, as oak, becomes very great,
Split piece Of such wood. and the
medullary plates appear and shine,
called by the artisan silver grain"
Let us now recapitulate the struc-
lures OF the stem as we have studied
them. In the center OF our section
lies the medulla, or pith, bounded on
the outer side by ring OF forming
wood. Next to this outwardly lies the
cambiuni, beyond which, again, is the
corteN, the forming structures OF the
bark, The elements Of bark and wood
are gathered plainly into groups, and
intervening between these several
groups, interceptng what would be
otherN c a continuous are, occur the
medullary rays,
Copyright, 1902 by Lewis d. sampson.l