54 
blood of all thofe is of adeep red; but, as the 
blood in {mall animals, excepting thofe only 
which live in the bowels of the earth, as 
many as I have known of them, want that 
purple colour; for this reafon then authors, 
who are only wife in their own fpeculation, 
have called them animalcula exfanguia, or 
animalcules without blood, though even in 
fome human bodies, there has been obferved 
fometimes white blood in the arteries. The 
blood of the Snail is of a glutinous confift- 
ence, clammy, and pituitous or phlegmatic; if 
poured into water, it fhews itfelf like a sky-co- 
loured cloud, which gradually expands, and 
grows more and more tenuous, and at length 
quite vanifhes; and is indeed a very pleafant 
fight. 
The blood which remains from the nu- 
trition of the membranes, returns through 
many extremely {mall veins toward the heart, 
there to undergo a new concoction. Thefe 
veins are chiefly fcattered about the exter- 
nal parts of the body, and are there very 
confpicuous ; for thofe veffels which we fee 
there, are almoft all confpicuous, as they may 
be feen among the pointed little glands of the 
verge. All thefe veins converge in one large 
trunk called the vena cava; which, as we 
have juft faid, may very plainly be feen on the 
internal fuperficies of that arched membra- 
naceous part of the rim or fringe of the Snail, 
Tab. V. fig. rv. 4; for the veins run off, under 
and through this verge or fringe, and after- 
wards difcharge their contents into the auri- 
cle d of the heart; which then, by its con- 
traction and fyftole, again protrudes this 
blood into the hearte; and the heart, with 
a manifeft circulation, again ejects it into the 
arteries, and thofe again into the veins ; that 
the motion may never be interrupted, but the 
blood maintain its courfe through the body. 
Hence the pulfation of the heart is firft 
difcerned in its auricle ; but afterwards in the 
heart itfelf; thofe veins which fpring from 
the vena cava, are formed and difperfed with 
fuch wonderful artifice, in the aforementioned 
membrane, that I have determined to fet forth 
an accurate drawing of them; to the end, 
that the works of God may be fo much the 
more clearly underftood, and more firmly 
impreffed on the memory. 
The heart, with its auricle, is never more 
diftinétly feen, than when it is cut open 
through the vena cava, diftended with a blaft, 
and then half dried ; but if it be dried too 
much, it is lefs forcibly contracted; and its in- 
ternal fabric and fmall valves cannot be fo 
conveniently viewed. But feeing thefe veffels 
all contain a whitifh or lightly-coloured blood, 
from which they may be eafily taken for 
nerves; it is therefore expedient that they be 
firft filled with an injection of fome coloured 
matter ; which operation, by reafon of the 
exceeding fmallnefs and finenefs of thofe 
parts, is indeed a very curious and difficult 
task. 
The (BrOv OTK “of ON AX UR Es tom 
For thofe who delight to engage in fuch a 
rocefs, there are colours of that fort which 
fubfide; and thofe ought to be mixed with fo 
fine a liquor, that it may pafs through the 
pores of the veffels, and fly off into the air. 
But ifany one ufe a liquor of a fimple colour, 
then they will be all of one tinge, nor can any 
thing be diftin@tly exhibited to the eye. I 
might explain many of the operations. and 
artifices requifite to the perfecting this matter ; 
but this part of the work, beyond my ex- 
pectation and defign, has grown redundant 
enough under my hands already. 
The difference between the blood and the 
flimy humour in the Snail is very remark- 
able, and may be obvioufly known only by the 
colour and confiftence ; for though the blood 
is thin and fluid in the veins, it becomes 
tenacious after it is taken out of thofe veffels. 
Nay, although it be immediately thrown into 
water, it does not mix therewith, unlefs it be 
fhook a little. On the other hand, the flimy 
humour fecreted by the glands, takes a long 
time before it is diffolved in water, becaufe 
it is tenacious and thick; and this is of a 
white colour, and may, therefore, by thofe 
qualities, be eafily diftinguifhed from the 
blood ; whenever the wounded Snail is 
thrown into the water, in order to mix the 
blood and this flimy humour with-it. 
The blood, being laid upon white paper, 
leaves no glofs; whereas the flimy humour 
covers it, as it were, with a bright varnifh, 
like filver; it may therefore be mixed with 
colours, to give them a glofs. Thofe, who eat 
Snails, efteem their blood very highly, and 
call it their liquor, taking particular care that 
it fhould not be loft; and I think they, as 
well as thofe who eat oyfters, have fome 
reafon for fo doing. 
After what manner the flimy humour 
diftils from the glands of the skin, may be 
feen in this manner ; the skin muft be wiped 
with {pungy blotting paper, until none of the 
flimy humour is feen, or till the whole is 
cleared off; then the skin muft be taken be- 
tween the fingers and prefled gently ; and if 
this be done under the microfcope, the flimy 
humour will be feen to come out infenfibly, 
from the glandular pores of the skin, like 
clear and minute points ; thefe, by continuing 
the preffure, will become {mall drops; and 
thefe, in fome time gathering together, will 
form a confiderable collection of this matter ; 
fo that the whole skin will be moiftened, and 
become glutinous. 
The cavity of the arched verge, in which 
the air moves, forms a round bow or arch, | 
occafioned by the membrane’s expanding 
itfelf againft the fhell; but this happens only 
when the Snail lies in its fhell; for when it is 
taken from thence, the membrane of the 
verge immediately flips into the parts under- 
neath ; fince it is no longer fuftained by this 
fupport againft the hell, being connected to 
the latter only by the toughnefs of the mucus, 
or 
