VEGETABLE STRUCTURE. 
67 
{hew us their flru6lure diflinflly, perhaps it may be known v/hen we view- 
all together. Only this we may obferve at prefent, that here is a pro- 
vilion of Nature for difeharging fome of the juice from tlie VelTels of the 
outer Bark, into the interftice betw^een that and the inner, v/ithout the 
vvafte of any between the two membranes of the Bark itfelf. We fee 
alfo the means by which thefe two coats of the Plant are faflened one to 
the other, and how maceration adts in procuring their feparation. 
These hairy fringes, which arife from the Veflels of the outer Bark, 
faften themfelves to the outer furface of the Rind under it; and as they 
are innumerable, and rife from fo many and fo near parts, they hold the 
two together through their whole furfaces : but as they are very tender, 
they are the lirH; things that didblve on lying long in water; and the band 
of union being deftroyed, they feparate. 
This Conftrudion of the Veflels of the outer Bark, explains alfo how 
it is that in the growing feafons we find a loofe fluid between the outer 
and the inner Barks of certain Shrubs and Plants. In the Mezereon I 
have obferved this particularly in early Spring ; and it is evident in the 
Stalks of all the Bulbous Plants. 
At Fig. 39, I have endeavoured to fliew the m.anner wherein the two 
Barks are united in the Body of the Root of Hellebore. The Figure re- 
prefenls a fmall piece vaftly magnified, as it appeared under the poliflfd 
iliell and double objed: glafs. a is the outer, b the inner Rind, feparated 
by the needle, and curling backwards, as they do immediately on the fe- 
paration. c c are the parts where the fringes of the mouths of the Vef- 
lels of the outer Bark faften themfelves to thofe of the inner. 
At Fig. 40, is reprefented a portion of the vafcular part of the outer 
Bark, feparated from its membranes : and as there is fome fmall difference 
in the courfe of the Veflels in the outer Bark of a, the flowering Stalk, 
from that in the body of the Root, a fmall piece of the Bark taken from 
the lower part of a Flower Stem of the Hellebore, is reprefented at 41 ; 
and the VelTels enlarged, and taken out from the membranes, at 42. The 
courfe of the Veflels is flraiter in the Stalk, from its length and flender- 
nefs, than in the body of the Root ; and their crofs-bars are lefs arched : 
indeed they are nearly horizontal ; but the conflrudion is the fame in 
both. Thefe have the fame mouths, with the fame fringes round them, 
and there are in the inner membrane the fame perforations. 
This is the conflrudion of the outer Bark of Hellebore. Knowing this, 
it will be proper to examine whether the outer Barks of other Plants re- 
K 2 femble 
