1 i.
t -
E X P L A I N E D BY THE MICROSCOPE;
e reprefcnts the Blea. This confifts of connefted circles, which have, in fo thin a pieces PLATE
viewed pcrpendicalarly, a great deal of the appearance of the bladders in the Bark j
only that their fides are wonderfully pale, indeed fo pale, that the whole Blca appears e
ds one uniform white mafs, exccpt to great attention, and very good glafles. Thefe
circles arc in reality of a different nature from the bladders of the Bark, as we ihall
fee, when each part is examined feparately j for they are indeed tranverfe feflions of
- elliptic veffek, arranged clofcly fide by fide together. Thefe are equal in their whole
diameter to the bladders of the Bark^ but their cavity is much lefs, becaufe their fides
are thick.
/ fliews the intimate, or moft inward Juice-velTels of the Oak : they are fdmewhát
larger in diameter than the conftituent veifels of the Blea j and they ftand fingly, not
in clufters, as the two former : they contain a thick and almoft concreted brown juice,
more auftere than that in the veflels of the Bark : and it is from thefe the Wood of
the Oak poffefles the fame auftere and aftringent qualities wi t h its Bark.
g. In the whole fpace f rom g Ì to g 2 we fee the Wood; This is compofed öf five
concentric circles, terminated by fo many undulated lines. Thefe arc the feverál coats
of Wood, added from feafon to feafon. It has been fuppofcd that each circle is the
growth of a year j but a careful attention to the encreafe of Wood has iliewn me, beyond
a doubt, that two fuch arc formed each year ; the one in Spring, the other footi
after Midfummer . At each of thefe times the Branch Ihoots out in length ; and
whenfoever that is done, the Shoot of the feafon before, gets an additional coat in
thicknefs : I lhall therefore be permitted to call thefe, inftead of Year Circles, Circles
of the Seafons. The Branch from which the prefent feftion was taken, having
been of two years and a half growth, there are found in it five fuch circles.
T h e compofition of the Wo o d is of veflels half obliterated, by the g rowt h of their fides
filling up their cavities inwardly; and fwelling out in the fame nianner externally; The
whole interftitial fpace being thus filled up, the very forms of them are by degrees loft.
At h are iliewn the Sap-veffels of the Oak. Concerning which, there have been
ftrange miftakes. But it is not my purpofe to point out where others have erred j but
plainly to lay down what I have feen, and what the obje€ls themfelves are ready to
make plain to every one.
Thefe vefiTels arife in the fubftance of the Wood, principally towards the outer edge
of each circle. They are very large in the outermoft coat j and fmaller in the others :
and there are alfo irregular ranges of them, running through the thickneíTfs of the
circles, befide thefe principal ones of the outer courfe. They have folid, and firm
coats J and they contain in Spring, and at Midfummer, a limpid liquor, like water,-
but with a flight acidity : at all other feafons of the year they appear empty, their
fides only being moiftened with the fame acid liquor. Thofe who éxariiined them ai
fuch feafons, thought them air-vefl"els ; and in that opinion, formed a conftruflion
for them, which Nature does not avow.
Í ihews the Corona, or Circle of Propagation; a part of the utmoft importance in the
Vegetable
/