[1] It was formerly thought that _Gassendi_ was really the genitive
of the Latin form _Gassendus_. C. Güttler, however, holds that it is
a modernized form of the O. Fr. _Gassendy_ (see paper quoted in
bibliography).
GASTEIN, in the duchy of Salzburg, Austria, a side valley of the Pongau
or Upper Salzach, about 25 m. long and 1¼ m. broad, renowned for its
mineral springs. It has an elevation of between 3000 and 3500 ft. Behind
it, to the S., tower the mountains Mallnitz or Nassfeld-Tauern (7907
ft.) and Ankogel (10,673 ft.), and from the right and left of these
mountains two smaller ranges run northwards forming its two side walls.
The river Ache traverses the valley, and near Wildbad-Gastein forms two
magnificent waterfalls, the upper, the Kesselfall (196 ft.), and the
lower, the Bärenfall (296 ft.). Near these falls is the Schleierfall
(250 ft.), formed by the stream which drains the Bockhart-see. The
valley is also traversed by the so-called Tauern railway (opened up to
Wildbad-Gastein in September 1905), which goes to Mallnitz, piercing the
Tauern range by a tunnel 9260 yds. in length. The principal villages of
the valley are Hof-Gastein, Wildbad-Gastein and Böckstein.
HOF-GASTEIN, pop. (1900) 840, the capital of the valley, is also a
watering-place, the thermal waters being conveyed here from
Wildbad-Gastein by a conduit 5 m. long, constructed in 1828 by the
emperor Francis I. of Austria. Hof-Gastein was, after Salzburg, the
richest place in the duchy, owing to its gold and silver mines, which
were already worked during the Roman period. During the 16th century
these mines were yielding annually 1180 lb. of gold and 9500 lb. of
silver, but since the 17th century they have been much neglected and
many of them are now covered by glaciers.
WILDBAD-GASTEIN, commonly called _Bad-Gastein_, one of the most
celebrated watering-places in Europe, is picturesquely situated in the
narrow valley of the Gasteiner Ache, at an altitude of 3480 ft. The
thermal springs, which issue from the granite mountains, have a
temperature of 77°-120° F., and yield about 880,000 gallons of water
daily. The water contains only 0.35 to 1000 of mineral ingredients and
is used for bathing purposes. The springs are resorted to in cases of
nervous affections, senile and general debility, skin diseases, gout and
rheumatism. Wildbad-Gastein is annually visited by over 8500 guests. The
springs were known as early as the 7th century, but first came into fame
by a successful visit paid to them by Duke Frederick of Austria in 1436.
Gastein was a favourite resort of William I. of Prussia and of the
Austrian imperial family, and it was here that, on the 14th of August
1865, was signed the agreement known as the Gastein Convention, which by
dividing the administration of the conquered provinces of Schleswig and
Holstein between Austria and Prussia postponed for a while the outbreak
of war between the two powers. It was also here (August-September 1879)
that Prince Bismarck negotiated with Count Julius Andrássy the
Austro-German treaty, which resulted in the formation of the Triple
Alliance.
See Pröll, _Gastein, Its Springs and Climate_ (Vienna, 5th ed., 1893).
GASTRIC ULCER (ulcer of the stomach), a disease of much gravity,
commonest in females, and especially in anaemic domestic servants. It is
connected in many instances with impairment of the circulation in the
stomach and the formation of a clot in a small blood-vessel
(thrombosis). It may be due to an impoverished state of the blood
(anaemia), but it may also arise from disease of the blood-vessels, the
result of long-continued indigestion and gastric catarrh.
When clotting takes place in a blood-vessel the nutrition of that
limited area of the stomach is cut off, and the patch undergoes
digestion by the unresisted action of the gastric juices, an ulcer being
formed. The ulcer is usually of the size of a silver threepence or
sixpence, round or oval, and, eating deeply, is apt to make a hole right
through the coats of the stomach. Its usual site is upon the posterior
wall of the upper curvature, near to the pyloric orifice. It may undergo
a healing process at any stage, in which case it may leave but little
trace of its existence; while, on the other hand, it may in the course
of cicatrizing produce such an amount of contraction as to lead to
stricture of the pylorus, or to a peculiar hour-glass deformity of the
stomach. Perforation is in most cases quickly fatal, unless previously
the stomach has become adherent to some neighbouring organ, by which the
dangerous effects of this occurrence may be averted, or unless the
condition has been promptly recognized and an operation has been quickly
done. Usually there is but one ulcer, but sometimes there are several
ulcers.
The symptoms of ulcer of the stomach are often indefinite and obscure,
and in some cases the diagnosis has been first made on the occurrence of
a fatal perforation. First among the symptoms is pain, which is present
at all times, but is markedly increased after food. The pain is situated
either at the lower end of the breast-bone or about the middle of the
back. Sometimes it is felt in the sides. It is often extremely severe,
and is usually accompanied with localized tenderness and also with a
sense of oppression, and by an inability to wear tight clothing. The
pain is due to the movements of the stomach set up by the presence of
the food, as well as to the irritation of the inflamed nerve filaments
in the floor of the ulcer. Vomiting is a usual symptom. It occurs either
soon after the food is swallowed or at a later period, and generally
relieves the pain and discomfort. Vomiting of blood (haematemesis) is a
frequent and important symptom. The blood may show itself in the form of
a brown or coffee-like mixture, or as pure blood of dark colour and
containing clots. It comes from some vessel or vessels which the
ulcerative process has ruptured. Blood is also found mixed with the
discharges from the bowels, rendering them dark or tarry-looking. The
general condition of the patient with gastric ulcer is, as a rule, that
of extreme ill-health, with pallor, emaciation and debility. The tongue
is red, and there is usually constipation. In most of the cases the
disease is chronic, lasting for months or years; and in those cases
where the ulcers are large or multiple, incomplete healing may take
place, relapses occurring from time to time. But the ulcers may give
rise to no marked symptoms, and there have been instances where fatal
perforation suddenly took place, and where post-mortem examination
revealed the existence of long-standing ulcers which had given rise to
no suggestive symptoms. While gastric ulcer is to be regarded as
dangerous, its termination, in the great majority of cases, is in
recovery. It frequently, however, leaves the stomach in a delicate
condition, necessitating the utmost care as regards diet. Occasionally
the disease proves fatal by sudden haemorrhage, but a fatal result is
more frequently due to perforation and the escape of the contents of the
stomach into the peritoneal cavity, in which case death usually occurs
in from twelve to forty-eight hours, either from shock or from
peritonitis. Should the stomach become adherent to another organ, and
fatal perforation be thus prevented, chronic "indigestion" may persist,
owing to interference with the natural movements of the stomach.
Stricture of the pylorus and consequent dilatation of the stomach may be
caused by the cicatrization of an ulcer.
The patient should at once be sent to bed and kept there, and allowed
for a while nothing stronger than milk and water or milk and lime water.
But if bleeding has recently taken place no food whatever should be
allowed by the stomach, and the feeding should be by nutrient enemata.
As the symptoms quiet down, eggs may be given beaten up with milk, and
later, bread and milk and home-made broths and soups. Thus the diet
advances to chicken and vegetables rubbed through a sieve, to custard
pudding and bread and butter. As regards medicines, iron is the most
useful, but no pills of any sort should be given. Under the influence of
rest and diet most gastric ulcers get well. The presence of
healthy-looking scars upon the surface of the stomach, which are
constantly found in operating upon the interior of the abdomen, or as
revealed in post-mortem examinations, are evidence of the truth of this
statement. It is unlikely that under the treatment just described
perforation of the stomach will take place, and if the surgeon is called
in to assist he will probably advise that operation is inadvisable.
Moreover, he knows that if he should open the abdomen to search for an
ulcer of the stomach he might fail to find it; more than that, his
search might also be in vain if he opened the stomach itself and
examined the interior. Serious haemorrhages, however, may make it
necessary that a prompt and thorough search should be made in order that
the surgeon may endeavour to locate the ulcer, and, having found it,
secure the damaged vessel and save the patient from death by bleeding.
Perforation of a gastric ulcer having taken place, the septic germs,
which were harmless whilst in the stomach, escape with the rest of the
contents of the stomach into the general peritoneal cavity. The
immediate effects of this leakage are sudden and severe pain in the
upper part of the abdomen and a great shock to the system (collapse).
The muscles of the abdominal wall become hard and resisting, and as
peritonitis appears and the intestines are distended with gas, the
abdomen is distended and becomes greatly increased in size and ceases to
move, the respiratory movements being short and quick. At first, most
likely, the temperature drops below normal, and the pulse quickens.
Later, the temperature rises. If nothing is done, death from the septic
poisoning of peritonitis is almost certain.
The treatment of ruptured gastric ulcer demands immediate operation. An
incision should be made in the upper part of the middle line of the
abdomen, and the perforation should be looked for. There is not, as a
rule, much difficulty in finding it, as there are generally deposits of
lymph near the spot, and other signs of local inflammation; moreover,
the contents of the stomach may be seen escaping from the opening. The
ulcer is to be closed by running a "purse-string" suture in the healthy
tissue around it, and the place is then buried in the stomach by picking
up small folds of the stomach-wall above and below it and fixing them
together by suturing. This being done, the surface of the stomach, and
the neighbouring viscera which have been soiled by the leakage, are
wiped clean and the abdominal wound is closed, provision being made for
efficient drainage. A large proportion of cases of perforated gastric
ulcer thus treated recover. (E. O.*)
GASTRITIS (Gr. [Greek: gastêr], stomach), an inflammatory affection of
the stomach, of which the condition of catarrh, or irritation of its
mucous membrane, is the most frequent and most readily recognized. This
may exist in an acute or a chronic form, and depends upon some
condition, either local or general, which produces a congested state of
the circulation in the walls of the stomach (see DIGESTIVE ORGANS:
_Pathology_).
_Acute Gastritis_ may arise from various causes. The most intense forms
of inflammation of the stomach are the toxic conditions which follow the
swallowing of corrosive poisons, such as strong mineral acids of alkalis
which may extensively destroy the mucous membrane. Other non-corrosive
poisons cause acute degeneration of the stomach wall (see POISONS).
Acute inflammatory conditions may be secondary to zymotic diseases such
as diphtheria, pyaemia, typhus fever and others. Gastritis is also
caused by the ingestion of food which has begun to decompose, or may
result from eating unsuitable articles which themselves remain
undigested and so excite acute catarrhal conditions. These give rise to
the symptoms well known as characterizing an acute "bilious attack,"
consisting in loss of appetite, sickness or nausea, and headache,
frontal or occipital, often accompanied with giddiness. The tongue is
furred, the breath foetid, and there is pain or discomfort in the region
of the stomach, with sour eructations, and frequently vomiting, first of
food and then of bilious matter. An attack of this kind tends to subside
in a few days, especially if the exciting cause be removed. Sometimes,
however, the symptoms recur with such frequency as to lead to the more
serious chronic form of the disease.
The treatment bears reference, in the first place, to any known source
of irritation, which, if it exist, may be expelled by an emetic or
purgative (except in cases due to poisoning). This, however, is seldom
necessary, since vomiting is usually present. For the relief of sickness
and pain the sucking of ice and counter-irritation over the region of
the stomach are of service. Further, remedies which exercise a soothing
effect upon an irritable mucous membrane, such as bismuth or weak
alkaline fluids, and along with these the use of a light milk diet, are
usually sufficient to remove the symptoms.
_Chronic Gastric Catarrh_ may result from the acute or may arise
independently. It is not infrequently connected with antecedent disease
in other organs, such as the lungs, heart, liver or kidneys, and it is
especially common in persons addicted to alcoholic excess. In this form
the texture of the stomach is more altered than in the acute form,
except in the toxic and febrile forms above referred to. It is
permanently in a state of congestion, and its mucous membrane and
muscular coat undergo thickening and other changes, which markedly
affect the function of digestion. The symptoms are those of dyspepsia in
an aggravated form (see DYSPEPSIA), of which discomfort and pain after
food, with distension and frequently vomiting, are the chief; and the
treatment must be conducted in reference to the causes giving rise to
it. The careful regulation of the diet, alike as to the amount, the
quality, and the intervals between meals, demands special attention.
Feeding on artificially soured milk may in many cases be useful. Lavage
or washing out of the stomach with weak alkaline solutions has been used
with marked success in the treatment of chronic gastritis. Of medicinal
agents, bismuth, arsenic, nux vomica, and the mineral acids are all of
acknowledged efficacy, as are also preparations of pepsin.
GASTROPODA, the second of the five classes of animals constituting the
phylum Mollusca. For a discussion of the relationship of the Gastropoda
to the remaining classes of the phylum, see MOLLUSCA.
The Gastropoda are mainly characterized by a loss of symmetry,
produced by torsion of the visceral sac. This torsion may be resolved
into two successive movements. The first is a ventral flexure in the
antero-posterior or sagittal plane; the result of this is to
approximate the two ends of the alimentary canal. In development, the
openings of the mantle-cavity and the anus are always originally
posterior; later they are brought forward ventrally. During this first
movement flexure is also produced by the coiling of the visceral sac
and shell; primitively the latter was bowl-shaped; but the ventral
flexure, which brings together the two extremities of the digestive
tube, gives the visceral sac the outline of a more or less acute cone.
The shell necessarily takes this form also, and then becomes coiled in
a dorsal or anterior plane--that is to say, it becomes exogastric.
This condition may be seen in embryonic _Patellidae, Fissurellidae_
and _Trochidae_ (fig. 1, A), and agrees with the method of coiling of
a mollusc without lateral torsion, such as _Nautilus_. But ultimately
the coil becomes ventral or endogastric, in consequence of the second
torsion movement then apparent.
[Illustration: From Lankester's Treatise on Zoology.
FIG. 1.--Three stages in the development of Trochus, during the
process of torsion. (After Robert.)
A, Nearly symmetrical larva (veliger).
B, A stage 1½ hours later than A.
C, A stage 3½ hours later than B.
f, Foot.
op, Operculum.
pac, Pallial cavity.
ve, Velum.]
The shell is represented as fixed, while the head and foot rotate from
left to right. In reality the head and foot are fixed and the shell
rotates from right to left.
The second movement is a lateral torsion of the visceral mass, the
foot remaining a fixed point; this torsion occurs in a plane
approximately at right angles to that of the first movement, and
carries the pallial aperture and the anus from behind forwards. If, at
this moment, the animal were placed with mouth and ventral surface
turned towards the observer, this torsion carries the circumanal
complex in a clockwise direction (along the right side in dextral
forms) through 180° as compared with its primitive condition. The
(primitively) right-hand organs of the complex thus become left-hand,
and vice versa. The visceral commissure, while still surrounding the
digestive tract, becomes looped; its right half, with its proper
ganglion, passes to the left side over the dorsal face of the
alimentary canal (whence the name supra-intestinal), while the left
half passes below towards the right side, thus originating the name
infra-intestinal given to this half and to its ganglion. Next, the
shell, the coil of which was at first exogastric, being also included
in this rotation through 180°, exhibits an endogastric coiling (fig.
1, B, C). This, however, is not generally retained in one plane, and
the spire projects, little by little, on the side which was originally
left, but finally becomes right (in dextral forms, with a clockwise
direction, if viewed from the side of the spire; but counter-clockwise
in sinistral forms). Finally, the original symmetry of the circumanal
complex vanishes; the anus leaves the centre of the pallial cavity and
passes towards the right side (left side in sinistral forms); the
organs of this side become atrophied and disappear. The essential
feature of the asymmetry of Gastropoda is the atrophy or disappearance
of the primitively left half of the circumanal complex (the right half
in sinistral forms), including the gill, the auricle, the osphradium,
the hypobranchial gland and the kidney.
In dextral Gastropods the only structure found on the topographically
right side of the rectum is the genital duct. But this is not part of
the primitive complex. It is absent in the most primitive and
symmetrical forms, such as _Haliotis_ and _Pleurotomaria_. Originally
the gonads opened into the kidneys. In the most primitive existing
Gastropods the gonad opens into the right kidney (_Patellidae,
Trochidae, Fissurellidae_). The gonaduct, therefore, is derived from
the topographically right kidney. The transformation has been
actually shown to take place in the development of Paludina. In a
dextral Gastropod the shell is coiled in a right-handed spiral from
apex to mouth, and the spiral also projects to the right of the median
plane of the animal.
[Illustration: From Lankester's _Treatise on Zoology_.
FIG. 2.--Four stages in the development of a Gastropod showing the
process of body torsion. (After Robert.)
A, Embryo without flexure.
B, Embryo with ventral flexure of the intestine.
C, Embryo with ventral flexure and exogastric shell.
D, Embryo with lateral torsion and an endogastric shell.
a, Anus.
f, Foot.
m, Mouth.
pa, Mantle.
pac, Pallial cavity.
ve, Velum.]
When the shell is sinistral the asymmetry of the organs is usually
reversed, and there is a complete situs _inversus viscerum_, the
direction of the spiral of the shell corresponding to the position of
the organs of the body. _Triforis, Physa, Clausilia_ are examples
of sinistral Gastropods, but reversal also occurs as an individual
variation among forms normally dextral. But there are forms in which
the involution is "hyperstrophic," that is to say, the turns of the
spire projecting but slightly, the spire, after flattening out
gradually, finally becomes re-entrant and transformed into a false
umbilicus; at the same time that part which corresponds to the
umbilicus of forms with a normal coil projects and constitutes a false
spire; the coil thus appears to be sinistral, although the asymmetry
remains dextral, and the coil of the operculum (always the opposite to
that of the shell) sinistral (e.g. _Lanistes_ among Streptoneura,
_Limacinidae_ among Opisthobranchia). The same, _mutatis mutandis_,
may occur in sinistral shells.
[Illustration: FIG 3.--Sketch of a model designed so as to show the
effect of torsion or rotation of the visceral hump in Streptoneurous
Gastropoda.
A, Unrotated ancestral condition.
B, Quarter-rotation.
C, Complete semi-rotation (the limit).
an, Anus.
ln, rn, Primarily left nephridium and primarily right nephridium.
lvg, Primarily left (subsequently the sub-intestinal) visceral
ganglion.
rvg, Primarily right (subsequently the sub-intestinal) visceral
ganglion.
cerg, Cerebral ganglion.
plg, Pleural ganglion.
pedg, Pedal ganglion.
abg, Abdominal ganglion.
bucc, Buccal mass.
W, Wooden arc representing the base-line of the wall of the visceral
hump.
x, 'x, Pins fastening the elastic cord (representing the visceral
nerve loop) to W.]
The problem of the causes of the torsion of the Gastropod body has
been much discussed. E.R. Lankester in the ninth edition of this work
attributed it to the pressure of the shell and visceral hump towards
the right side. He referred also to the nautiloid shell of the larva
falling to one side. But these are two distinct processes. In the
larva a nautiloid shell is developed which is coiled exogastrically,
that is, dorsally, and the pallial cavity is posterior or ventral
(fig. 2, C): the larva therefore resembles _Nautilus_ in the relations
of body and shell. The shell then rotates towards the left side
through 180°, so that it becomes ventral or endogastric (fig. 2, D).
The pallial cavity, with its organs, is by this torsion moved up the
_right_ side of the larva to the dorsal surface, and thus the left
organs become right and vice versa. In the subsequent growth of the
shell the spire comes to project on the right side, which was
originally the left. Neither the rotation of the shell as a whole nor
its helicoid spiral coiling is the immediate cause of the torsion of
the body in the individual, for the direction of the torsion is
indicated in the segmentation of the ovum, in which there is a
complete reversal of the cleavage planes in sinistral as compared
with dextral forms. The facts, however, strongly suggest that the
original cause of the torsion was the weight of the exogastric shell
and visceral hump, which in an animal creeping on its ventral surface
necessarily fell over to one side. It is not certain that the
projection of the spire to the originally left side of the shell has
anything to do with the falling over of the shell to that side. The
facts do not support such a suggestion. In the larva there is no
projection at the time the torsion takes place. In some forms the
coiling disappears in the adult, leaving the shell simply conical as
in _Patellidae, Fissurellidae_, &c., and in some cases the shell is
coiled in one plane, e.g. _Planorbis_. In all these cases the torsion
and asymmetry of the body are unaffected.
The characteristic torsion attains its maximum effect among the
majority of the Streptoneura. It is followed in some specialized
Heteropoda and in the Euthyneura by a torsion in the opposite
direction, or detorsion, which brings the anus farther back and
untwists the visceral commissure (see Euthyneura, below). This
conclusion has shown that the Euthyneura do not represent an archaic
form of Gastropoda, but are themselves derived from streptoneurous
forms. The difference between the two sub-classes has been shown to be
slight; certain of the more archaic Tectibranchia (_Actaeon_) and
Pulmonata (_Chilina_) still have the visceral commissure long and not
untwisted. The fact that all the Euthyneura are hermaphrodite is not a
fundamental difference; several Streptoneura are so, likewise
_Valvata, Oncidiopsis, Marsenina, Odostomia, Bathysciadium,
Entoconcha_.
_Classification._--The class Gastropoda is subdivided as follows:
Sub-class I. Streptoneura.
Order 1. Aspidobranchia.
Sub-order 1. Docoglossa.
" 2. Rhipidoglossa.
Order 2. Pectinibranchia.
Sub-order 1. Taenioglossa.
Tribe 1. Platypoda.
" 2. Heteropoda.
Sub-order 2. Stenoglossa.
Tribe 1. Rachiglossa.
" 2. Toxiglossa.
Sub-class II. Euthyneura.
Order 1. Opisthobranchia.
Sub-order 1. Tectibranchia.
Tribe 1. Bullomorpha.
" 2. Aplysiomorpha.
" 3. Pleurobranchomorpha.
Sub-order 2. Nudibranchia.
Tribe 1. Tritoniomorpha.
" 2. Doridomorpha.
" 3. Eolidomorpha.
" 4. Elysiomorpha.
Order 2. Pulmonata.
Sub-order 1. Basommatophora.
" 2. Stylommatophora.
Tribe 1. Holognatha.
" 2. Agnatha.
" 3. Elasmognatha.
" 4. Ditremata.