130 ^ Treatise on 
Rocks, Stones or other Bodies by a broad thin 
Bafts , formed by an Expanfion of its ftony Sub- 
ftance. The Bark, which covers the Bofis , Trunk 
and Branches, when the Coral is newly taken out 
of the Water, is eafily feparated from the inte- 
rior Part, but with greater Difficulty when it is 
dry. Externally it is uneven, rough, and beftrewed 
as it were with Grains, which are perforated in the 
Middle by a fmall Aperture, to receive the nutri- 
tious Juice from the Water that furrounds it. More- 
over, from the Surface of the Bark arife Papilla 
or fmall Glands diftributed here and there, hollow 
within and divided in many Cells, which have an 
Orifice opening at the Top of the Papilla fome- 
times oblong, fometimes round, but more fre- 
quently divided into fix Chinks, fo as to exhibit 
the Form of a Star. The internal Surface of the 
Bark is ftriated or marked lengthways with Fur- 
rows, which correfponding to thofe on the Surface 
of the (tony Subftance, when they are applied 
upon each other conftitute Canals, through which 
the nutritious Juice is diffufed over the whole 
Plant. In the ftony Subftance likewife are difcover- 
ed Cells, containing a Juice like the Papilla of the 
Bark. W T hiIft the Plant is growing in the Water, 
its Canals, Papilla and Cells are turgid with a 
vifcous milky Juice, of an acrid and fomewhat 
aftringent Tafte, approaching to theTafte of Pep- 
per and Chefnut. When it has been expofed for 
lome Time to the Air, this Juice is infpiflfated, 
dried and converted into a yellowiffi friable Sub- 
ftance, void of Acrimony, having only a gentle 
Aftringency. 
At the Tops of the Branches are foft Tubercles 
compofed of the cortical Subftance, diftinguiffied 
into different Cells, and replete with the fame 
milky Juice. They are foft, like the Bark, when 
firft 
