i€o Of the Bark of trees'. 
rous of rdund ones; whereas in the foregoing the lym- 
phaedudte are contiguous to the wood, and the roriferous 
more or lefs diftant from the {kin ; here, on the contrary, 
the firft are diftant from the wood, and the latter con¬ 
tiguous to the {kin. 
In the two next branches, fig. 486 and 488. the veffels 
of the bark are alfo different in number, pofition, fize 
and kind. In pine they are lefs, and in walnut more 
numerous j as to their pofition, the inmoft D C in pine, 
fig. 488. compofe a radiated ring, the utmoft are ftrag- 
ling up and down without any certain order. In walnut, 
fig. 486. the inmoft D C make alfo a radiated ring, and 
the outmoft a double ring H R I, not radiated but of 
round parcels: as to their kind, they differ moft appa¬ 
rently from the diverfity of faps thofe different veffels 
contains which in the bark of pine, fig. 488. are alfo of 
two forts, the inmoft are lymphaeduds, as in the two 
formers the outmoft are not milk, but gum veffels, or 
refiniferous, and ftand {haggling or fingly about the 
bark; all the clear turpentine that drops from the tree 
iffues from thefe veffels, which are apparent even to the 
naked eye; whereas thofe of the lymphaedmft are not to 
be difcerned without the affiftance of a microfcope. 
The two next pieces of branches are common fumach, 
fig. 494. and common wormwood, fig. 490. which arc 
remarkable for their having three kind of veffels in the 
bark, whereas the former have only two. Firft then 
in common fumach is a thick radiated ring D M C of 
lymphsedudts, Handing on the inner margin of the bark 
contiguous to the wood ; thefe veffels exhibit their lymph a 
very apparently. The fecond kind of veftels X X com¬ 
pofe a ring, and are fituate near the outward margiji of 
the bark. Between thefe two kinds ftand the milk vef¬ 
fels 
