2 4 TH E C O N S T R U C T I O N OF TIMBER
P L A T E thefe Clufters of the Corona. In thofe fpecics where that fpungy ma t t e r of the wood,
J , Fig. 3. is ^ery loofe and open, the cuttings grow very freely: in thofe where the
d. Fig. 3. fame fubftancc is m u c h more compadl, and prefles more upon the veiTcls, they grow
more difficultly; and where it is very hard, they will not in the common method grow
a t all. It will be wort h the praflical Gardener' s while to attend to this: for to raife
fuch trees f rom cuttings there requires only to wound in many places this interior
woody fubftance, anH that way to give the veflels freedom. He muft not be expeded
t o ufe Microfcopes to find them out, 'tis fufficient that he be told in general where
t h e y are} they lie deep, juH above the P i th; and when he would raife a Tree or
S h r u b of the harder kinds from cuttings, he is only to cut deep into the piece all
round, as furgeons fcarify : he will deftroy many of the par ts; but enough will remaia
t o furni i h ma t t e r for fome Shoots.
Something of this t rut h fcems to have been conceived b y p radical Gardeners; fome of
w h o m have recommended flitting, flafliing, or pricking holes in the part of a cutting
or flip to be put into the ground. Others have decried the praf t ice; and, as they fay,
f r om ill fuccefs u p o n the trial. Both may write truly : but they have judged too generally
on a f u b j e a wher e the matter depends upon the different ftrudiure of particulars.
H e that cuts or pierces a foft fpecies, wher e the part furrounding thefe veflels is loofe
and open, lets in deftrudion and rottennefs to the whole : but he who performs the
fame operation upon kinds where it is har d and too compaf t , gives courfe t o the natural
powers and method of encreafe. If thefe kinds be fcarified, and the others fecured
by wax f rom the too free ingref s of the moi i lur e of the earth, few will fail.
C H A P . IX .
OF THE Pi t h .
1 N the center of every young Shoot of a tree refides the P i t h : greater in fome, and
A lefs in others 3 but prefent in all. It is placed clofe wi thi n the Corona j the moifteni
n g of whofe clufters, and giving moderate and regulated way to their extenfion, is its
great office: for the thing itfelf, and its deftined ufes, have been miftaken. It is fuppofed
coeval or primordial to all the other parts j but it is indeed poftnate, and comes
a f t e r them in the order of time, as well as in its ufes. It is no other than a cellular
fubftance, formed from the inner furface of the Corona, when the growt h of the
c l u f t e r s of that part begins. We fee nothing of it in the Corona itfelf, tho' ever fo
carefully examined; for it does not exift in that part while dormant : but as foon as a
c l u f t e r leaves the circle, and its par t s feparate for growth, this fpungy matter is formed
w i t h i n them. Exhaled air gives origin to its Blebs, whi l e the thicknefs of the juices,
cloathing the Bubble, give it form and fubftance.
Thus
E X P L A I N E D BY THE MICROSCOPE.
T h u s is this interior fubftance formed, which has been fuppofcd primsval, and the PLATE
great caufe of produdlion, of all the reft. Its office is required only wliile thefe
clufters take their firft growth, and it adls no longer. The firft feafon is the time
o f its great ufe, and it immediately after begins to decay.
T h u s we fee trees have par t s of limited and temporary ufe. The great veflels of the
wood perform their office for feveral years j but it is only at particular ftatcd feafons :
i n Spring and at Midfumme r we find them in their duty, full of their proper fluid;
a t otlier times vacant and inaftive : the Pith, in the fame manner , lives and ai t s for the
firft year j and fcarce longer.
T h e ftrufture of the Pi t h has been as l i t t l e underftood as its office: figures have been
p u b l i i h e d of it, reprefenting it as formed in circles, hexagons, and polygons, with
ftarry points, and double lines, and an infinity mor e of various configuration : yet the
t h i n g is but one. To fee it truly, we muf t look wher e it is moft fimple. The Wal -
nut affords i t in this condition. If we fplit a Shoot of the common Walnut, of the
g r o w t h of one feafon, direftly down the middle, we fee the central part divided acrofs
i n t o feveral cells by thin membranes, as in Plate IX. Fig. i. 2. Each of thefe cells Fi<J. i . 2.
i s oblong, fmalleft at the ends, and larger in the middle, as Fig. i. a. and examining Fig. i. a.
t h e fmaller part, we very diftinftly fee two membranes forming the two fides of the
cell, and feparate f rom the membranes of the cells above and below, tho' they join
t h e one and the other in the middle b. Following the courfe of this furrounding I
membrane round the whole of any one cell, we iee that cell in its true nature r it is
a n oval Bladder or Bleb, of which this membrane forms the oval. Such a one is reprefented
alone at Fig. 3. The whole of the Pith is the fame wi t h its parts; there- Fig. 3.
f o r e the P i t h of the Wa l n ut confifts onl y of one range of thefe bladders, fmaller at the
edges, largeft in the middle, and laid very exaftly one upon another, The Corona
of the Shoot keeps them in their place f ideways: they have no weight, fa they do not
prcfs upon one another downward ; and therefore they retain this form.
I t is only in very f ew trees that the P i t h is of this fimple conftrudiion j but having
feen it tlius i n one, we fliall underftand it in all. It is the quality of the Corona to
t h r ow out little bladders of air, clofed in thin membranes; they are large in the Waln
u t , and therefore each reaches acrofs the whole branch; but in other trees they are
f m a l l ; and many of them muft be laid horizontally together to extend from fide to
fide of the Shoot. In the Dog-Rofe, reprefented at Fig. 5. we fee it takes ten or Fig. 5.
twelve circles of the Pi t h Blebs, to fill the vacant middle of the Branch : but ftill
t h e f e Blebs are the fame as in the Walnut j only that here they are fmal l and round;
i n that large and oval. .
One of thefe Blebs, feparated from thofe above, below, and on each fide of it,
a p p c a r s - a s a t F i g . 6. Fi g . 6.
I t will be obferved that at F ig. 5. where the whole body of the Pith is reprefented Fig. 5.
t o g e t h e r , the outline of every Bleb appears double; and, as it were, jointed in feveral
places. This is one of thofe wonders which have been reprefented in elaborate en-
4 gr a v i n g s :
4
ill