ANA' 
The pylorus is a fold or duplicature of the two inner 
coats of the flomach, the nervofa and villofa ; and it is 
formed in part by a fafciculus of flefliy fibres fixed in the 
duplicature of the tunica nervofa, and diding'uilhed not 
only from the other Helhy fibres of the extremity of the 
ftomach, but alfo from thole of the intellines, by a thin 
whitilh circle, which appears even through the external 
or common coat, round the union of the flomach and in¬ 
tellines. The figure of the pylorus is that of a ring tranf- 
verfely flatted ; the inner edge of which, or that next the 
centre, is turned obliquely towards the intellines. This 
inner edge runs naturally more or lefs into little plaits or 
gathers, like the mouth of a purfe almolt (hut; all which 
.particulars are very different from/what figures and dried 
preparations would make us believe. It is therefore a 
kind of fphindter, which can contract the inferior orifice 
of the flomach, but feenis not capable of (hutting it quite 
dole. The flomach receives in general whatever the 
mouth and tongue fend thither through the canal of the 
oefophagus : but its particular ufe is to receive the ali¬ 
ments; to contain them fora longer or fhorter time, in 
proportion as they are more lolid or fluid ; and to digell 
them, and to put them in a condition to be turned into 
that nutritious fluid called chyle. This operation, which 
goes by the general name of digrjlion, is performed partly 
by the fuccus galtricus, which flows continually from the 
tunica villofa, and partly by the continual contraction and 
relaxation of the mufcular coat. Thefe motions in men 
are but very weak, and no wdfe fufficient for digellion, 
without the afliftance of the alternate motions of the dia¬ 
phragm and mufcles of the abdomen. The pylorus, or 
flefliy circle of the inferior orifice of the flomach, ferves 
to retain the aliments in it till they have acquired a fuffi- 
cient degree of fluidity to pafs ealily through that open¬ 
ing. But, by a particular irritation of the mufcular coat 
■of the flomach, and Hill more by a violent contraction of 
the diaphragm and mufcles of the abdomen, the contents 
of the (tomach may be very foon forced towards the final 1 
extremity, and pufhed through the pylorus into the in¬ 
tellines. The gentle and alternate motions of the orbicu¬ 
lar fibres of the mufcular coat may alfo aflill in fending 
through the pylorus, in the natural way, the aliment that 
is diffidently digefted. This was called the pcrijlaltic or 
vermicular motion, by thofe who believed that it is fuccef- 
fively reiterated, like that of earth-worms when they creep. 
Trituration might be a proper term for this operation, 
provided it be 'made to fignify only a gentle agitation or 
aCtion of the flefliy fibres in a fubdance continually moif- 
tened by the galtric liquor, and not a violent grinding of 
a dry fubllance. 
Between the pylorus and the very lowed part of the 
abdomen lies a long canal, bent in a great many different 
directions by numerous convolutions, called the intejlincs. 
This canal, thus folded and turned, forms a confiderable 
bulk, which fills the greated part of the cavity of the abdo¬ 
men ; and it is connected through the whole extent to mem¬ 
branous pijpduCtions or continuations of the peritonaeum, 
but principally to thofe called the mefentery and mefocolon. 
The whole canal is generally about fix or feven times as 
long as the fubjeCt; and it is divided into three portions, 
which are diflinguilhed by particular names. In the fmall 
intedines, the three portions are named duodenum, jejunum, 
and ileum ; and in the great intellines, ccccum, colon, and reElum. 
The intejlina tenuia, or fmall intedines, form one continued 
uniform canal; and, although the three portions of it have 
three different names, yet we have no fufficient marks 
whereby to didinguilh them, to fix the precife extent or 
length of each portion, or to fettle its jud limits. 
The intejlina craffa, or great intedine#, are one continued 
canal, divided into three portions, like the fmall ones. The 
intedinum caecum is only a round Ihort broad bag, the bot¬ 
tom of which is turned downward, and the mouth or open¬ 
ing upward. It lies under the right kidney, and is hid by 
the lad convulution of the ileum. On one fide of the bottom 
©f the caecum lies an. appendix, refembling a fmall intef- 
Vol. 1 . No. 39. 
r o m y. 613 
tine, nearly of the fame length with the caecum, but very 
(lender. It is termed apbcndicula vermformis, from its fup- 
pofed refemblance to an eartlt-wm'.r.. The colon is the mod 
confiderable of all the intedines. From the catcum, of 
which it is a continuation, it reaches to the lower part of 
the left lvypochondrium. Its continuity is, however, a lit¬ 
tle interrupted by the ileum, which advances into the cavi¬ 
ty of the colon, and, together with a certain fold of that in- 
tedine, forms what is called valvula coli. The capacious arch 
of the colon is connected by both extremities to the regio 
lumbaris, near the kidneys, by two particular ligaments, 
one on the right fide, the other on the left, which are only 
fmall duplicatures of the peritonaeum, more or lefs tranf- 
verfe. The lad of the intedines is named reflum, or the 
Jlraight gut, from its fituation ; for, when viewed directly 
forward, it appears to run down in a draight courfe from 
the lad vertebra of the loins, on the fore-fide of the os 
facrum, all the way to the os coccygis, where it ends in 
what is called the anus. This intedine is a true continua¬ 
tion of the laft convolution of the colon; and it is the re- 
pofitory of the whole intedinal canal. It has likewife a 
fpecial relation to the bladder, and to the parts of gene¬ 
ration in both fexes. 
The intedines are not left to move at random in the ca¬ 
vity of the abdomen; but are artfully bound down by a 
membranous web, which prevents the intedinal convolu¬ 
tions from being intangled in each other, and from being 
twided or comprelfed in all their different ways of meet¬ 
ing ; and yet allows them a gentle floating, but limited 
motion. This web goes by the Greek name of mefentery , 
as being in fome meafure in the middle of the intedines. 
It is didinguilhed into two portions; one of which being 
very broad, and very much plaited, connects the fmall in¬ 
tedines ; the other, which is long and incurvated, does the 
fame office to the great intedines. Thefe two portions 
form a kind of fpiral roll, more or lefs plaited in its cir¬ 
cumference. The fird portion is the mefentery ; the other 
is termed mefocolon. The mefocolon is the continuation of 
the mefentery ; which, having reached the extremity of the 
ileum, contrails and changes its nahne. At this place, the 
particular lamina, which is turned to the right fide, forms 
a fmall tranfverfe fold, called lig amentum coli dextrum. Be¬ 
tween the laminae of the mefentery, a great number of 
glands lie fcattered through the cellular fubdance. Thefe 
glands are of the number of thofe that anatomids call 
glandulce conglobatce, the druCture of which is not as yet fuf¬ 
ficiently known. The niced anatomical injections have 
not hitherto given us any fatisfaCtion about them ; for, 
though they be made with all poffible care, they always 
fill the follicitlous texture of thefe glands; and though, 
by means of thefe injections, we may difeover a great many 
velfels which were before invifible, we do not advance 
much nearer our purpofe, becaufe we cannot, by this me¬ 
thod, didinguilh the fecretory, excretory, and blood-vef- 
fels from each other. 
OF DIGESTION. 
Both the pain of hunger, and the pleafttre of gratifying 
the appetite, excite us to the performance of an aCtion ab- 
folutely necelfary for our fupport, viz. the taking a due 
portion of aliment, in order to counterbalance the wade 
of the body by the infenlible perfpiration and other eva¬ 
cuations ; and for which purpofe the functions of the ab¬ 
dominal vifcera, hitherto deferibed, were principally in¬ 
tended. The neceflity of frequently taking food is increafed 
by the blood, which being naturally of a faline quality, 
foon acquires an acrimonious putrefcency, by the evapo¬ 
ration of its thin watery parts; and this evaporation being 
increafed by the heat of the body, and the motion of the 
heart and arteries, nature calls drenuoufly for a recruit of 
the watery element, by which the cohefive globules of the i 
blood are feparated from each other, and hindered from 
running together into a folid mafs. Thefe truths are pro¬ 
ved, not only from their caufes, but likewife by the ap¬ 
pearances which they exhibit in men and oilier animals 
<j R \ darved 
