Of the Bark of Roots . 245 
to be that part which compofed the cortical body the year 
before, which by the generation of a new ring next the 
wood, is now thruft outward, and fhrunk up into a (kin 
as at A B ; in an horfe-raddifh root, fig. 473. or at A B 
in a buglofs root, fig. 475. as far as the bladders in the 
former, and veffels in the latter, are radicated; the corti¬ 
cal body feems to fhrivel up into a new fkin, as the old 
ones fall off, and probably the whole body-of the perpen¬ 
dicular roots, except the woody fibre in the center, be¬ 
comes the fecond fkin, as in afparagus, fig. 467. 
This fkin is made up of two kinds of bodies, one pa- 
renchymous, generally compofed of exceeding finall cells 
or bladders, which are plainly vifible, if viewed through a 
microfcope, and appear as in fig. 467. which reprefents a 
tranfverfe piece of the root of afparagus, &c. 
The other part of this fkin is compofed of tubular 
wood-veffels, intermix’d wdth the bladders before-men- 
tion’d. 
If a root be cut tranfverfly, and laid by for fome time, 
all the parts where there are no veffels will fhrink below 
the furface of the cut end ; but the veffels will all retain 
the fame length, at which time they may be examined by 
the microfcope. 
Of the bark of roots. 
T HE bark is fituatejuft within the fkin, in fotne roots 
it is yellow, as in dock, red in biftort, but in moft 
white, in fome it is very thin, and in others it makes the 
greatefl part of the root, the thinneft and thickeft being 
all analogous. 
It is exceeding porous both in length and breadth, as 
appears from its fhrinking up equally both ways, and di¬ 
lating to its former fize on being foaked in water. All 
R 3 this 
