192 M E M O I R S of the 
Juices, which the heads, or fecd-veffels of plants afiFord, may 
be thought oF the fame nature with thofe, which the pulp of 
fruit affords -, the pulps of fruits, and th^efe exterior veffels 
being parrs equivalent 5 that is, apples, for inftance, are nothmg 
elfc but the feed-veffels of their kernels. This juice of Cen^ 
tattry is liquid upon the firft drawing, and after a while it 
thickens, feparating no whey, and is of the colour of amber 5 it 
fticks to one's fingers, and draws out into threads, like bird- 
lime 5 it would never become harder than very foft wax, and 
that by being dried in the fliade only^ for if ever fo little 
expolcd to the heat of the fun, or fire, it immediately becomes 
exceeding foft • but the cakes made up of it and wheat flower, 
were in winter become very hard and firm, and the unmixed 
cakes continued ftill foft; they burn with an unpleafant fmell, 
emit a lading flame, ftill retain their amber colour, and draw 
out into threads in burning, like wax. To this we may add 
the yellow juice, which the wounds of ^wge//<:^ fatiya^ Park, 
yield; it will not harden by being expofed to the fun, or by 
being long kept, yet it becomes ftiff, and draws out into 
threads. 
The next fort of coagulated, or clammy juices, are gums; 
and fome of them feem to continue for a long time liquid, and 
perhaps inflammable; others there are which grow hard, and 
arc not to be kindled into flame; they are ealily diflblved in 
fountain-water, and fparkle when put into a flame; which two 
properties argue a ferous or watry part in them; again, put 
into a flimc, they melt, and become, as it were, liquid and 
du(5tile, which fliews their cheefy part, and becaufe they will 
not flame, it is an argument of their leannefs and fcarcity of 
oil; all thefe three things, put together, plainly evince gums 
to be coagulated juices. 
In Augufl, Dr. Liiter obferved both the green and ripe 
clullersof ^Periclymemim, Gcr. very leaky ; which upon a nearer 
infpeiSlion he found to be a thin clammy juice, or liquid gum, 
which fell down upon the leaves, and retained its fluid form 
there ; here the purple iuice fcems to be a whey leparated 
from the liquid gum, but Dr. Liiier rather thmks, it is a 
diftinfl liquor. 
The red threads of Ror'ella end in little bags, which, bcmg 
compiefled, yield a purple juice; and thcfe fruall buttons are 
cncompaiTed with fmall tranlparent pearls, or drops ot a liquid 
gum ; they continue in this form the hotteft d.iy in fummcr like 
dew, whence alio the plant has its name, and upon the ieaft 
touch 
