on account o f the finenefs of the melhes, the hardnefs o f the
wood, and the famenefs of colour in the conftituent fibres.
We are here only fpeaking of the lymphatic veffels or lignous
fibres of the wood, which exift in it as well as in the bark,
though in different ftates; for the lignous fibres are always harder
and lefs flexible than the cortical ones. Malphigi thinks they
differ in another particular, namely, that a juice or fluid ifl'ues
from the cortical, while none is found in thofe o f the wood. In
this !it would appear from the obfervations o f Duhamel, that he
was miftaken.
A tranfverfe feflion of wood generally appears formed o f a
number of rays proceeding from the corona to the bark, which
are interfefiled at different diftances by concentric circles, inter-
fperfed with veflels o f varying magnitude: the variations in this
ftruQure afford much pleafure to the curious obferver, and throw
confiderable light upon the-nature and properties o f timber ; for
it is by means of a variety o f ftrainers that different juices are prepared
from the fame mafs. Matter, confidered as matter, has.no
fhare in the qualities o f bodies. It is from the arrangement, o f
it, or the recipient forms given to it, that we have fo many differ^
ent fubftances. Accordingto the modifications that thefe receive;
we fhaJl find the fame light, air, water, and earth, manifefting
themfelves in one b.y a deadly poifon, and in another by the mofl
falubrious food A lemon ingrafted upon an orange flock, is. capable
o f changing the fap o f the orange into it’s own nature, by a
different arrangement of the nutritive juices. One mafs of earth
will give life and vigour to the bitter aloe, to the fweet cane, the
cool
cool houfe-leek, and the fiery muflard, the nourifhing grain, and
the deadly night-fhade.
The wood may be confidered as Compofed o f two parts, lignous
and - parenchymous. We have, already treated of the
former; the latter is that which is difpofed into rays running as
it were between the lignous fibres, and interweaving with them;
it originates either with the pith or corona. There is a 'very
great diverfity in thefe radial infertions, in fome trees there are
very few, while they abound in others; in fome they are very
fine, in others very thick. In texture they feem fimilar to
the blebs of the bark, only that here they are fo crouded and
flretched out as to appear like parallel threads, fomething fimilar
to a net when drawn tight.
O f t h e C o r o n a .
Dr. Hill gives this name to that circle which furrounds the
pith, and feparates it from the wood; although in his opinion it
differs greatly from both, and in its compofition has no refem-
blance to either. It is, according to him, the moft important
partin the whole vegetable fabric, by which the propagation and
increafe o f the branches, buds, and Ihoots, is carried on. *
It has been ufual to fuppofe the pith of vegetables to be the
part in which thefe wonderful fources of increafe refides, but this
is not the cafe; and he aliens, that fo far from being prior to the
other parts, it is in reality pollerior to fome of them.
The