Oxford Democrat. [volume] (Paris, Me.) 1833-1933, 1902-11-11

Transverse Section OF Maple IWl9
Highly MagnIfled. c.-The Cam
blum Line.
think of trees in this way, 1t Is plain
that all our surface knowledge counts
but little. We are in the presence OF
mechanism Of wonderful efficiency.
but also Of great completely. whose
delicate adjustments may tax the cum
ming Of the wisest.
Now, In q few short chapters which
constitute this course a complete an
swer to the problem Of the tree or
even a complete statement of 1t Is
certainly not to be expected. We may
perhaps study the problem In some OF
its simpler aspects, learn q little or
the structure of tree. Of its history.
and more Of its utility and exceeding
value to enlightened men and nations.
Perhaps the most striking peculiarly
of the tree is its persistence. other
plants grow, send up stems and leaves
and flowers, begin many Of the things
done by the tree, but these presently
perish. survive q few months or years
ut most and are gone. Only plants of
the tree type seem able to accumulate
to carry forward the work OF life and
make each year contributory to life's
perennial triumph. Fortunately this
particular property Of the tree. taking
things as they are. admits OF compara-
lively simple explanation. We find the
explanation in 80 far in the trees struc-
ture, Just as in the case of any mech
anism we may study the parts and find
out how they work and so understand
the machine. If we make thin cross
section of the stem Of small tree and
Law the section under the lens OF NIL
croscope, we shall see something ike
that shown in the accompanying Illus
tration. which is indeed from photo
graph of such q section.
Here the whole section seems made
I'D of little rings. The early observers
thought =. csc rings looked like a sec
ton Of a ,oneycomb and accordingly
chilled them cells. At q glance we per-
ceIye that the rings or cells are not
alike They differ greatly in size and
shape. A second glance shows US that
the cells fall easily into groups which
form together a circle around within
the margin. The cells which make uT
this band or circle are in the growing
tree, all living cells and all active, each
in it's 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 W
q narrow band, marked G In the figure.
II is to these tiniest but ever living cells
that the tree Of the forest owes 1t
character, Its long enduring vigor. Be-
ing living cells, these can grow, and by
their peculiar way Of growing they az
complish three things-they lie between
bark and wood, and all the time In the
grow ing 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
noyo or to be added to the wood al
ready in position; the middle cells of
the bund simply divide and divide and
80 keep up 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
cells to form living sheath covering
the whole tree, lying between bark and
wood. In spring we very easily pull
the bark frsm living tree-a willow,
for instance-the separation occurring
in the plane of this living but proper.
tionately delicate cell layer. This liv'
Ing. active layer has long been named
the camblum. We shall refer to it
again.
But let US look at our section again.
We may discover gill another pecul.
iarity. 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 medulla.
They may be regarded as ut first part
Of the medulla. They form the medul.
larry rays. They build as they grow
vertical plates radiating outwardly
from the center Of the tree. At first
the plates are comparatively few, but
as growth proceeds the primary rays
are continually REINFORCED by others,
originating indeed In the persistent
cambium and intercalated between
those already formed until their num-
Der, as may be seen in any bit Of
wood, as oak, becomes very great.
spHt . piece Of such wood, and The