Foreign Vegetables. 167 
ducive in no fmall Degree ; that is, their acrid fa- 
line Particles, both fixt and volatile : For thefe, en- 
tering the Mouths of the Velfels, and circulating 
through them, are mingled with the Juices, which 
they dilfolve and melt down, fo as to render the 
whole Mafs of Blood more fluid. Hence a more 
copious Afflux of Serum is derived from every Part 
of the Body to the Inteftines, which at the fame 
Time are ftimulated by the oily Particles. And 
this is the Reafon why ftrong Catharticks provoke 
an Evacuation fo plentifully by Stool. 
But thefe oily Parts being condenfated in a large 
Quantity by an acid Salt, into a refinous Concrete, 
and expanded upon the nervous Membranes, the 
Irritation they produce is too great ; whence are ex- 
cited Gripings of the Guts, or fpafmodick Twitch- 
ings, fucceeded by very fparing Difcharges of a 
vifcid Matter by Stool, and fometimes none at all. 
On the contrary, the acrid Salts, conftituting the 
greater Part of the gummous Concrete in Combina- 
tion with a few diluted oily Particles, do not irri- 
tate the nervous Coats, fo much as they mingle 
with the Humours, and diflblve them. However, 
as fome Afliftance from the refinous Parts is necef- 
fary to ftimulate the Inteftines to throw off the 
Humours which have been diflfolved, it is therefore 
that purging Medicines exert their ACfion more ef- 
fectually, when their Gum and Refin are together, 
than when either the one or the other of them are 
given in a feparate State. 
Moreover, thefe bitter oily Parts, which are 
found in great Quantity in Colocynth, and are fo 
highly offenfive to the Nerves, whether they be 
condenfated into a Refin by acid Salts, or by acrid 
Salts expanded into a Gum, or whether they be 
feparated from both thefe Kinds of Salts by Diftil- 
lation, or by the Means of Fermentation fubtilized 
M 4 and 
