A buccal cavity, a pharynx, an oesophagus and an intestine are always distinguishable.

Pharynx and oesophagus are concealed in the head.

avellanarius, the common dormouse, distinguished by the cylindrical bushy tail, and thickened glandular walls of the cardiac extremity of the oesophagus; thirdly, Eliomys, containing several species, with tufted and doubly vaned tails, simple stomachs and smaller molar teeth, having concave crowns and faintly marked enamel-folds; and lastly, the African Graphiurus, represented by several species, with short cylindrical tails ending in a pencil of hairs, and very small molars almost without trace of enamel-folds.

A so-called heart lies on the dorsal surface of the oesophagus; it is closed behind, but in front it opens into a circumoesophageal ring, which gives off vessels into the lophophore and tentacles.

The cavities of the hollow tentacles open into a circular canal which surrounds the oesophagus at the base of the lophophore.

The oesophagus is provided often with caeca which in Syllids and Hesionidae have been found to contain air, and possibly therefore perform the function of the fish's air-bladder.

In medicine, nitric acid is used externally in a pure state as a caustic to destroy chancres, warts and phagadenic ulcers; and diluted preparations are employed in the treatment of dyspepsia, &c. Poisoning by strong nitric acid produces a widespread gastroenteritis, burning pain in the oesophagus and abdomen and bloody diarrhoea.

bd, Enlargement of the oesophagus, armed with chitinous teeth..

The detorted visceral commissure shows a tendency to the concentration of all its elements round the oesophagus, so that except in the Bullomorpha and in Aplysia the whole nervous system is aggregated in the cephalic region, either dorsally or ventrally.

constricted between the oesophagus and pylorus; while in the dormouse the oesophagus immediately before entering the stomach is much dilated, forming a large egg-shaped bag with thickened glandular walls; and in certain other species, as in Lophiomys and.

This may be associated with mud-eating habits; but it is not wholly certain that this is the case; for in Chaetogaster and Agriodrilus, which are predaceous worms, there is no protrusible pharynx, though in the latter the oesophagus is thickened through its extent with muscular fibres.

It is clear that, if we start from the condition of full eversion of the tube and watch the process of introversion, we shall find that the pleurecbolic variety is introverted by the apex of the tube sinking inwards; it may be called acrembolic, whilst conversely the acrecbolic tubes are pleurembolic. Further, it is obvious enough that the process either of introversion or of eversion of the tube may be arrested at any point, by the development of fibres connecting the wall of the introverted tube with the wall of the body, or with an axial structure such as the oesophagus; on the other hand, the range of movement of the tubular introvert may be unlimited or complete.

This bilobed sac becomes entirely the liver in the adult; the intestine and stomach are formed from the pedicle of invagination, whilst the pharynx, oesophagus and crop form from the stomodaeal invagination ph.

The mouth is devoid of armature, and passes without break into the oesophagus; this is surrounded by the retractor muscles, which are inserted into the skin around the mouth, and have their origin in the bodywall, usually about one-third or one-half of the body-length from the anterior end (figs.

This subsequently closes up, and the newly-formed oesophagus and stomach open in the intestine above and behind it.

Anteriorly it finally communicates with the lacunae just mentioned, which surround the oesophagus, bathe the posterior lobes of the brain, pass through the nerve ring together with the proboscidian sheath, and are generally continued in front of the brain as a lacunar space in the muscular tissue, one on each side.

Such glands occurring on the upper and lower lips or on the walls of the oesophagus have been regarded as salivary.

The labial commissure supplies only the buccal mass and the oesophagus and stomach.

To the left of this is the fissure for the ductus venosus, and to the left of this again, the left lobe, in which a broad shallow groove for the oesophagus may usually be seen.

For this reason it is used to remove corneal opacities, deafness due to thickening of the membrane, stricture of the oesophagus and hypertrophy of the pylorus, it has also been successful in the treatment of adhesive parametritis.

It consists of a definite contractile sac or sacs lying on the dorsal side of the alimentary canal near the oesophagus, and in preparations of Terebratulina made by quickly removing the viscera and examining them in sea-water under a microscope, he was able to count the pulsations, which followed one another at intervals of 30-40 seconds.

The central nervous system may be described as consisting of a collar surrounding the oesophagus, and two pairs of cords arising from the collar and passing backwards.

There is a welldeveloped brain dorsal, to the mouth; this gives off a pair of oesophageal commissures, which surround the oesophagus and unite in a median ventral nerve-cord which runs between the longitudinal muscles to the posterior end of the body.

It is a remarkable fact, not yet understood, that in certain Enchytraeidae and Lumbriculidae the spermathecae open into the oesophagus as well as on to the exterior.

The mouth, situated at the opposite end and armed with a pair of stylets, leads into an oesophagus, into which the ducts of a pair of so-called salivary glands open.

The diagnostic features of the class Scyphozoa thus constituted are supposed to be (I) an ectodermal oesophagus or stomodaeum, (2) a gastric cavity subdivided by mesenteries, (3) gonads formed in the endoderm.

The stomach, oesophagus and intestine are ciliated on their inner surface.

Above the oesophagus is a thin commissure which passes laterally into the chief armnerve.

Outside the wall of the oesophagus a vascular space has been detected which is in direct continuity with the longitudinal blood-vessels.

In certain cases, however, the walls of the oesophagus appear to be very closely applied to the muscular body-wall and this vascular space thereby considerably reduced.

The alimentary tube consists of three regions: firstly, the anterior buccal mass with the oesophagus, of ectodermic origin, and therefore bearing cuticular structures, namely the jaws and radula; secondly, the mid-gut, of endodermic origin and including the stomach and liver; and, thirdly, the hind-gut or intestine.

In the region of the oesophagus these muscles are more strongly developed to perform the movements of deglutition, and, where a gastric mill is present, both intrinsic and extrinsic muscles co-operate in 3a producing the movements of its 36 various parts.

On the other hand, additional longitudinal trunks are sometimes developed, the chief one of which is a supra-intestinal vessel lying below the dorsal vessel and closely adherent to the walls of the oesophagus in which region it appears.

The oesophagus is often furnished with glandular diverticula, the "glands of Morren," which are often of complex structure through the folding of their walls.

In addition to the musculature of the proboscis and proboscidian sheath, longitudinal muscular fibres are found in the walls of the oesophagus, whilst transverse ones are numerous and united into vertical dissepiments between the successive intestinal caeca, thus bringing about a very regular internal metamerization.

There is some evidence that in this group the ectoderm of the oesophagus is chiefly concerned with digestion, whereas the endoderm of the intestine is limited to the absorption of the soluble products.

In the anthopolyp the blastopore is carried inwards by an in-pushing of the body-wall of the region of the peristome, so that the adult mouth is an opening leading into a short ectodermal oesophagus or stomodaeum, at the bottom of which is the blastopore.

The treatment consists in the use of solutions of common salt, followed by copious draughts of milk or white of egg and water or soap in water, in order to dilute the poison and protect the mucous membranes of the oesophagus and stomach from its action.

The polyp (hydropolyp) is of simple structure, and never has an ectodermal oesophagus or mesenteries.

The oesophagus is short and leads into a long, straight stomach, provided with numerous symmetrical lateral caeca.

The oesophagus is the anterior portion of the digestive canal; its walls are folded longitudinally, comparatively thick and provided with longitudinal muscular fibres.

The Hydromedusae are distinguished from the Scyphozoa chiefly by negative characters; they have no stomodaeum, that is, no ingrowth of ectoderm at the mouth to form an oesophagus; they have no mesenteries (radiating partitions) which incompletely subdivide the coelenteron; and they have no concentration of digestive cells into special organs.

The former leads to a protrusible pharynx (B), from which the oesophagus opens into a wide intestinal chamber with branching lateral diverticula.

So has the acrembolic pharynx of Chaetopods, if we consider the organ as terminating at that point where the jaws are placed and the oesophagus commences.

In the region of the mouth where the two halves of the small arm-sinus approach one another they open into a central sinus lying beneath the oesophagus and partly walled in by the two halves of the ventral mesentery.

This sinus is continued round the oesophagus as the peri-oesophageal sinus, and thus the whole complex of the small arm-sinus has the relations of the so-called vascular system of a Sipunculid.

Two pairs of glands open into the buccal cavity, and at the junction of pharynx and oesophagus is another pair called the sugar glands.

It has been sought to prove that the interior of the hypostome is lined by ectoderm, so as to form a stomodaeum or ectodermal oesophagus similar FIG.

A pair of cerebral ganglia lie on the dorsal side of the oesophagus: they innervate the proboscis or head and its tentacular lobes and captacula.

These two vessels in the Oligochaeta are united in the anterior region of the body by a smaller or greater number of branches which surround the oesophagus and are, some of them at least, contractile and in that case wider than the rest.

In a few Enchytraeidae and Lumbriculidae the spermathecae open at the distal extremity into the oesophagus, which is a fact difficult of explanation.

There is no armature, and no glands, and the whole tract can only be divided into an oesophagus and an intestine.

Anteriorly these chords embrace the oesophagus and unite with the cerebral mass which innervates the pair of eyes when present.

oes., Oesophagus.

oe, Oesophagus.

f, Oesophagus.

c, Oesophagus.

They are all pelagic, the foot being entirely transformed into a pair of anterior fins; eyes are absent, and the nerve centres are concentrated on the ven tral side of the oesophagus.

Visceral commissure short, tendency to concentration of all ganglia in dorsal side of oesophagus.

Visceral commissure reduced; nervous system concentrated on dorsal side of oesophagus.

s, Oesophagus.

vag, Nerves for oesophagus.

vagus) for the oesophagus.

No trace of nephridia is found posterior to the oesophagus.

ce, oesophagus.

The mouth, which is quite devoid of armature, leads imperceptibly into a short and dorsally directed oesophagus.

A vessel - the dorsal vessel - runs forward from the heart along the dorsal surface of the oesophagus.

There is thus a vascular ring around the oesophagus.

Oesophagus.

Like the chief armnerve, this strand runs through the lophophore, parallel indeed with the former except near the middle line, where it passes ventrally to the oesophagus.

Lastly the nervous system is well developed and consists of a pair of well-marked and interconnected ganglia placed near the anterior end and dorsal to the oesophagus.

dentaries; some of the vertebrae in the lower region of the neck have strongly developed hypapophyses (not provided with a cap of enamel, as has often been asserted), which are directed forwards and pierce the oesophagus.

The mouth may lead directly into the stomach, without any oesophagus.

The foot has been developed into long processes which have extended in a circle round the mouth; all the ganglia, including the visceral, have been concentrated around the oesophagus.

s.o., Oesophagus.

A small stomatogastric commissure bearing two small ganglia arises from the cerebral ganglia and surrounds the oesophagus.

d, Oesophagus.

The drug affects only the involuntary muscles of the eye, just as it affects only the involuntary or non-striated portion of the oesophagus.

They may have been swallowed several hours before symptoms of acute poisoning show themselves, with nausea and vomiting, and a burning in the oesophagus, stomach and abdomen.

The effects of the ingestion of large quantities may be so rapid that death may take place in a couple of hours, owing to collapse, consequent on perforation of the walls of the oesophagus or stomach, or from asphyxia due to swelling of the glottis consequent on some of the acid having entered the larynx.

Should the patient survive the first twenty-four hours death generally results later from stricture of the oesophagus or intestine, from destruction of the glands of the stomach or from exhaustion.

The calcareous skeleton, which may be entirely absent, is usually in the form of minute spicules, sometimes of small irregular plates with no trace of a calycinal or apical system; to these is added a ring of pieces radiately arranged round the oesophagus.

side of the loop of the alimentary canal (a, a") and by two lateral mesenteries (a') which further connect the oesophagus with the V o.i.

From this the blood passes into two lateral vessels which pierce the coelomic septum (s.), the right vessel proceeding on the anterior side of the oesophagus, as shown in fig.

ce, Oesophagus.

groppo, whence English "group"), the ingluvies, or pouched expansion of a bird's oesophagus, in which the food remains to undergo a preparatory process of digestion before being passed into the true stomach.

This leads to a muscular oesophagus with a triradiate lumen, ~kCi LT Chaetonotus maximus, Ehrb., ventral side.

Over the latter the dense white smooth epithelial lining of the oesophagus is continued, terminating abruptly by a raised crenulated border.

oesophagus with the stomach The stomach forms by far the largest part of the alimentary canal.

The muscular pharynx, extending back into the space between the first and second pairs of legs, is followed by a short tubular oesophagus.

oesophagus goes down your gullet (also called the esophagus) to your stomach.

2, ph.), oesophagus (oes.), stomach (st.) and intestine (int.) may be distinguished.

i, Excretory pore j, Oesophagus.

(I) The polyp (hydropolyp) is of simple structure, typically much longer than broad, without ectodermal oesophagus or mesenteries, such as are seen in the anthopolyp (see article Anthozoa); the mouth is usually raised above the peristome on a short conical elevation or hypostome; the ectoderm is without cilia.

The " introvert " in these Gastropods is not the pharynx The ctenidium is monopectinate and attached to the mantle along as in the Chaetopod worms, but a prae-oral structure, its apical limit being formed by the true lips and jaws, whilst the apical limit of the Chaetopod's introvert is formed by the jaws placed at the junction of pharynx and oesophagus, so that the Chaetopod's introvert is part of the stomodaeum or fore-gut, whilst that of the Gastropod is external to the alimentary canal altogether, being in front of the mouth, not behind it, as is the Chaetopod's.

The introversible tube may be completely closed, as in the " proboscis " of Nemertine worms, or it may have a passage in it leading into a non-eversible oesophagus, as in the present case, and in the case of the eversible pharynx of the predatory Chaetopod worms. The diagrams here introduced (fig.

The nervous system of Helix is not favourable as an example on account of the fusion of the ganglia to form an almost uniform ring of nervous matter around the oesophagus.

ance in this region inevitably follows, Oesophagus and and when further contractions of the mouth shown by walls of the sheath ensue total exdotted lines.

Two lateral outgrowths of the foremost portion of the oesophagus, afterwards becoming constricted off, as well as two ingrowths from the epiblast, contribute towards its formation, at least as far as both Metaand Heteronemertines are concerned.

places it has sunk into the con Passing from the middle line outwards they are - (i.) the median pallial nerve to the middle of the dorsal mantle; (ii.) numerous small nerves - the circum-oesophageal commissures - which pass round the oesophagus to the chief arm-nerve or supra-oesophageal ganglion; (iii.) the under arm-nerve to the lophophore and its muscles; (iv.) the lateral pallial nerve to the sides of the dorsal mantle.

c, Nearly ripe cercariae; cc, cystogenous cells; dr, daughter-redia; dt, limbs of the digestive tract; f, head-papilla; h, eye-spots; h', same degenerating; k', germinal cell; 1, cells of the anterior row; m, embryo in optical section, gastrula stage; n, pharynx of redia; o, digestive sac; oe, oesophagus.

Oesophagus, stomach, radial canals, ring-canal and tentacle-canals, constitute together the gastrovascular system and are lined throughout by endoderm, which forms also a flat sheet of cells connecting the radial canals and ring canal together like a web; this is the so-called endoderm-lamella (e.l.), a most important feature of medusan morphology, the nature of which will be apparent when the development is described.

In the primitive Phyllopoda, and less distinctly in some other orders, the nerves supplying the antennae arise, not from the brain, but from the circum-oesophageal commissures, and even in those cases where the nerves and the ganglia in which they are rooted have been moved forwards to the brain, the transverse commissure of the ganglia can still be traced, running behind the oesophagus.

Among mammals, o, oesophagus; st, stomach; p, pylorus; ss, small intestine breviated); c, caecum; ll, large intestine colon, ending in r, the rectum.