Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 8, ELE-FOR

Part II.
FARRIERY.
441
Anatomy or, but the cardiac the moft To, with the leffer extre-
of the mity rather pofterior to the other, and the great eurva-
Horfe. ture inferior. It is evident that the fituation of the
u'"""v flomach muft vary much with its diftenfion : the fore¬
going defcription anfwers to it when moderately dif-
tended only ; but where it is very much filled, the left
extremity will prefs upon the diaphragm, and the
right wdll be carried more pofteriorly. In oxen and
ftieep, where the firft ftomach is large, it is found, when
diftended, to have its left extremity carried quite into
the left iliac region ; in which part it is ufually punctu¬
red, when they are hoved : but fuch an idea of the
ftomach of the borfe would prove very erroneous ; for
this animal has a very fmall one, and therefore its fitu-
* 1 ation can never be fuch
v0ofr From a diftended ftomach preffing upon the dia¬
phragm, we are at no lofs to underftand, why breathing
is impeded after a full meal, when a horfe appears to
labour for breath ; for he is forced to ufe the intercoftal
mufcles, and the mufcles of the (boulder and fore ex¬
tremities, to open the cheft, the pofterior enlargement
being prevented from the diaphragm being fixed by the
preffure of the ftomach ; hence we fee the great impro¬
priety of galloping horfes after watering, to warm it in
their bellies, as it is foolilhly termed. Horfes, when
grazing, if they drink, are never obferved to do this j
if it was neceffary, nature would diClate it to them.
How hurtful it is likewife to ride hard, after a horfe
has been full fed, is equally evinced. The ftomauh
has externally a covering from the peritoneum, which
adheres clofely to it, by means of its cellular portion ;
and which portion is dipping in between the mufcular
fibres. Its middle portion is made up of mufcular fibres,
which are more numerous in this animal, than in the
ruminant ; making this kind of ftomach a medium be¬
tween the membranous one of fome animals, and the
true mufcular ftomach of others. The direClion of
thefe fibres is various 5 but they may principally be
referred to a longitudinal and a tranfverfe order,
’though neither of them are regularly fo, and are inter¬
mixed with others, whofe dire&ion is very oblique, and
interlaced with each other. The longitudinal plane is
the moft external of the two, and appears a continua¬
tion of the external plane of the cefophagus, with
fome original fibres, which fpread over the leffer cur¬
vature, being carried obliquely round, and likewife
over the great extremity, forming themfelves into a
kind of vertex, whofe centre is in the middle of that
extremity. The inner plane is by much the larger,
and is not quite circular, but (lightly oblique, crofting
the obliquity of the longitudinal plane. This circular
plane is very thick and ftrong round the cardia, or
that extremity into which the oefophagus terminates.
105 They are here fo very thick as to form a tru« fphinc-
Reafotw for ter ; and to this it is in fome meafure owing, that a
tne horfe’s horfe cannot vomit ; for when the circular and longi¬
tudinal fibres are afting from the pylorus to the cardia,
by any irritation that reverfes the ufual motion, pro¬
ducing an effort to vomit, the circular and longitudinal
fibres of the cardia being infinitely ftronger and more
numerous, are contrafting this orifice (efpecially the
circular), as the others are contracting the other parts ;
for as the mufcular fibres exift equally throughout the
ftomach, by which the motions are effected, it cannot
be fimplv from the exiftence of the circular covering to
Vol, VIII. Part II.
i")t vomit
fng,
the firft portion of his ftomach, that he cannot vomit ;
for it is reafonable to fuppofe the fibres aft throughout
the ftomach by the common conlent of parts ; nor do
they of actual neceflity want an immediate ftimulus to
their furfaces ; for were this the cafe, the fibres of the
ceiophagus would not by the’prefence of the mafticated
bolus be ftimulated to contrail through the cuticular
coat, which equally here lies over the fibres; nevcrthe-
lels, the cuticular coat of the ftomach is probably aflift-
ing in this difficulty to regurgitate : it does it by leffen-
ing the liability to naufea, which feldom takes place in
the horfe ; and as vomiting is only an effort to remove
naufea or its caufe, fo nature not having given the dif-
eafe, has not provided the means for its removal. As
likewife vomiting appears to be a reverfing of the peri-
ftahic motion of the ftomach ; which motion, in its na¬
tural ftate, begins from the cardia, and ends at the py¬
lorus ; fo in this reverfed ftate, it commences at the
pylorus, and ends at the cardia, thus regurgitating its
contents ; fo it is very probable that the cuticular co¬
vering may leffen this inverted periftaltic motion in the
upper portion, though it cannot wholly deftroy it ; and
hence cannot be the only, or the principal reafon of the
impoflibilily, or rather of the difficulty with which this
animal vomits; for inftances have occurred where it
has taken place. A horfe in Suffex was feen to regur¬
gitate a large quantity of grains, and we have heard of
one or two other inftances; but thefe muft be regarded
as very rare occurrences.
It is not, therefore, that the ftomach of the horfe
cannot be irritated to make an attempt to vomit, that
no fuch effift generally takes place; for though it is
but very leldom that naufea occurs, and perhaps never
in a ftate of nature, yet it may be excited by means of
aconite, hellebore, and fome other fubftanees, which
have caufed fruitlefs efforts to vomit. But the true
and principal reafon that a horfe may be faid, naturally
not to be able to vomit, arifes, in that nature has wife¬
ly fo conftrudled the parts, that the very effort to it
increafes the refiftance by the very ftrong fphinfler
placed at the mouth of the cardia. Had this refiftance
not been placed, and every means taken to rncreafe the
almoft impoflibility of vomiting in a horfe, it is evident
that from the curtain of the palate flopping the open¬
ing of the mouth, this aiffion, had it taken place, would
have occafioned fuffocation. The inner coat of the
ftoraach is corapofed of two portions, the one cuticular
and the other villous. This fpecies of cuticular cover¬
ing to nearly one half of the ftomach, is peculiar to
fuch animals as appear deftined to live on grain, as
horfes, affes, rats, and mice ; and this forms a third
fpecies of ftomach between the true membranous one of
graminivorous animals, and the umfcular of the carni¬
vorous tribes, and it may be conndered in a flight de¬
gree, as a fpecies of gizzard, refembling the ftru£iure
of thofe animals, as fowls, who have organs to make up
for the want of teeth. For a horfe has not the means
of re-maftication, as in oxen or ftieep, nor does he ufu¬
ally mafticate his food at firft fufficiently to comminute
it ; for the wants of the conftitution ftimulate him to a
hafty deglutition of his food, which, if there was not
fome other ftrufture than that common to ftomachs in
general, would not be fuffieiently digefted : for the food
i> folid, and the ftomach fmall ; therefore this cilticular
coat may be uftTul, as its infenfibility allows it to prefs
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