direct.connection with the alimentary canal,
until near its division into the terminal
trunks by which it enters the spleen. Here
it gives off a left gastro^iploic artery ; and



STOMACH AND INTESTINE,



327



numerous small and short vessels, the vasa
brevia.

The gastro-epiploica sinistra (i,figs. 250,251 .)
leaves the trunk of the splenic artery close
to where this divides at the inner surface of
the spleen. It passes downwards, forwards,
and towards the right side, first lying for a
short distance in the gastro-splenic omentum,
and then entering between the layers of the
great omentum which is continuous with this
fold. It then runs along the lower border or
great curvature of the stomach, to anastomose
with the corresponding vessel on the right
side. Like it, it supplies branches to both
surfaces of the stomach.

The vasa brevia are numerous small branches
which come from the primary and secondary
divisions of the splenic artery, and run in the
gastro-splenic omentum to the cardiac pouch.
Here they break up and anastomose with
each other, as well as with the coronary and
left irastro-epiploic arteries.

The veins of the stomach are the superior
pyloric, and the right and left gastro-epiploic.

The vena pylorica superior receives and
continues a large vein, which corresponds to
the coronary artery, and takes a similar (but
reversed) course along the lesser curvature of
the stomach to the pylorus. It now passes
upwards for a little distance, before opening
into the vena portce (a, Jig. 281.) near its ter-
mination in the liver. In other instances, it
bends down to join the splenic vein.

The vena gas/ro-epiploica dextra corre-
sponds to its artery in the greater part of its
distribution. It usually ends by emptying
itself into the superior mesenteric vein, just
before this forms the vena portce by joining
with the splenic vein (e, Jig. 281.).

The venn gastro-epiploica sinistra also runs
with its artery, and joins either the splenic
vein, or one of its primary branches.

All of the foregoing vessels are characterized
by the great freedom and frequency of their
inosculations in every stage of their course
from the aortic to the'portal trunks. This con-
dition is especially well marked in the arteries.
And, as ordinarily injected, the latter ap-
pear to be both larger and more numerous
than the arteries distributed to an equal bulk
of most of the other structures of the body.*

* Assuming this fact to be as true as it seems to
be, it becomes interesting to inquire what peculiari-
ties of the circulation may be presumed to be con-
nected with it. Other things being equal, the pas-
sage of a larger quantity of blood to and from an
organ may be fairly supposed to be associated with
a greater amount of that change which absorption
or secretion there impress upon this fluid. Again,
Yolkmann's researches have shown that the anas-
tomosis of channels diminishes the resistance in
their interior; a diminution which, if not met
by any counteracting circumstance, would increase
the velocity of their contents. But the most plau-
sible conjecture that can at present be offered is,
that this increase in the number of these small ar-
teries, which have a distinctly muscular struc-
ture, and are plentifully supplied with nerves, has
reference to that efficient and sudden control of their
calibre which the varying exigencies of their capil-
lary circulation would seem to imply.



Their tortuous course, and their loose con-
nection with the stomach, chiefly refer to the
distention of this organ. For as the stomach
expands between the laminae of peritoneum,
it gradually straightens these vessels, and
alters their position with respect to itself
and to each other.

The distal branches of the arterial and
venous trunks perforate the muscular coat
at different intervals, by twigs which unite
with each other in the loose submucous
areolar tissue, so as to form two broad
and somewhat flattened networks : one,
which is composed of small arteries, and
another, of veins. The vessels of the latter
plexus are, as usual, both larger and more
numerous than the corresponding arteries.

Capillaries. The arterial branches which
leave the above sub-mucous network, to enter
the dense muscular layer of the matrix of the
stomach, divide here once or twice. And their
ultimate ramifications, which have a diameter
of about T-gfoffth to T TOTr tn of an inch, pass
vertically upwards, along the sides of the tubes
to their upper apertures, where they form a
superficial network of capillaries. In passing

Fig. 252.




Plan of the vessels of the mucous membrane of the
stomach, as they would be seen in a vertical section.

a, arteries from the plexus occupying the sub-
mucous areolar tissue; 6, superficial plexus of capil-
laries occupying the ridges of the mucous mem-
brane; c, veins passing downwards between the
gastric'tubes ; d, capillaries between and around the
tubes ; e, plexus of arteries and veins occupying the
snbmucous areolar tissue.

upwards, they also give off other capillaries ;
which surround the tubes, at all parts of
their height, with a second and deeper net-
work. The meshes of this latter plexus are
somewhat oblong, but less decidedly so than
those of the capillary network of striped
muscle; and are about T ^th to T o tn of an
inch in size. The capillaries which compose
them are, on an average, little more than
7 J^-yth of an inch in diameter. The more
superficial netwoik is contrasted with this
deeper one, not only in the fact that its capil-
laries are about double the above diameter (or



328



STOMACH AND INTESTINE.



^.j^-th of an inch), but also in its meshes being
nearly twice as close (or about T ^th to ^^th
of an inch). But the two plexuses inosculate
so freely, as to be quite continuous with each
other at the upper apertures of the tubes. As

Fig. 253.




Superficial capillaries of the mucous membrane of the
human stomach, from an injected specimen. Mag-
nified 70 diameters.
a, ridges intervening between the sto mach -tubes ;

b, capillaries occupying the ridges ; c, orifice of a

stomach-tube.

regards the form of the superficial network, it
may be stated to correspond exactly with the
intervals of the primary tubes. For the
ridges which occupy the surface of the organ
are all, as it were, moulded upon capillaries,
the union of which forms what we may distin-
guish as a primary network, that surrounds the
aperture of each tube with a capillary loop.
In Man,* however, this comparatively simple
network is complicated by the addition of
other meshes, which lie on either side of it,
and just within the orifices of the tubes. In
their shape and size, these closely resemble
the loops beneath the ridges, and are, indeed,
no way distinguishable from them except in
their situation. Below, their diameter di-
minishes, their loops elongate, and they
finally merge into the general network which
surrounds the tubes.

It is from the large capillaries which com-
pose the superficial network that the radicles
of the veins almost exclusively arise. They
begin as small vessels of about -ITOU^ f au
inch in diameter ; and by one or two suc-
cessive unions of these* and their resulting
larger branches, they soon attain a width of
about 7 io tn of an inch. They now pass
vertically down the intervals between the
tubes, to open into the flattened venous plexus
which occupies the submticous areolar tissue.

The general result of this arrangement on
the circulation in the stomach seems to be,
that the blood which has already traversed
the capillaries of its tubes is passed on to its
surface. Hence in respect to their situation
and size, these superficial capillaries of the
gastric mucous membrane offer a distant re-
semblance to veins. This fact, as well as their
connection, both with small arteries on the
one hand, and with confluent capillaries on



* In many animals the superficial network appears
limited to this simpler form ; especially in the cardiac
region, Avhere the intervals of the tubes are smaller.



the other, renders it probable that the velo-
city of their contents exceeds that of the
blood which circulates in the capillaries of
many other tissues. Such a peculiarity would
admirably adapt them to that absorptive office
which their mere situation on the cavitary
surface of the organ indicates as one of their
chief functions.

Changes in the stomach during digestion.
The introduction of food into the healthy
fasting stomach gives rise to two chief altera-
tions in the organ. Its muscular coat is ex-
cited* to movement. And, at the same time,
its mucous membrane deepens from a pale to a
bright pink colour f ; and begins to pour forth
a liquid secretion the gastric juice.

Gastric juice. An inquiry into the cha-
racters of the gastric juice is opposed by
many difficulties. For it is obvious that the
properties of this or any other secretion can
only be established from its examination in a
state of perfect purity. While the situation
and functions of the' stomach are such that,
under natural circumstances, its secretion is
necessarily mixed with many other substances.
It is true that the bile often found J in the
stomach during fasting is shut out from its
cavity, during digestion, by the closure of the
pylorus. But, on the other hand, the saliva,
which generally covers the mucous surface of
the empty organ, as a thin viscid layer with
a superficial alkaline reaction, is swallowed
at this period in much larger quantities; while
the food itself forms an equally constant
impurity. To such less avoidable sources
of error are often added the alterations pro-
duced by disease in the unhealthy individual,
or by putrefaction or digestion in the healthy
subject after death. And though even the
most careful study of all these circumstances
will scarcely explain the discrepancies and
contradictions of numerous (and apparently
faithful) observers in their accounts of the gas-
tric juice, still they evidently constitute con-
ditions which, according as they are obviated,
or noticed, or neglected, will respectively
render any particular observations valid, or
comparable, or utterly useless.

* See ante, p. 312.

f Beaumont, Op. cit. pp. 94. et seq.

I See ante, p. 315.

The above remarks form a key to the following
historical summary of the more important observa-
tions which have been made on this fluid ; as well as
a reason why the author has reduced it to a mere
enumeration, such as will not, however, preclude a
fuller subsequent reference, where this is required.

Reaumur, in the year 1752, obtained an artificial
digestive fluid from the stomachs of animals by
means of sponges attached to strings (Me'm. de
1'Academie, 1752. pp. 705. et seq.). About 1780,
Spallanzani (Ueber das Verdauungsgeschaeft. Leip-
zig, 1785) adopted the same method; and also ex-
amined matters which had been vomited. He thus
determined the gastric juice to be a neutral, anti-
septic solvent. He quotes Scopoli and Gosse to the
same effect. Carminati (Untersuchungen ueber die
Natur des Magensaftes, 1785) also deduced his
results from substances vomited ; and found that it
was only the acid fluid secreted after eating which
possessed antiseptic and digestive powers. Several
observers, however, among whom were Viridet



STOMACH AND INTESTINE.



329



Physical Properties. Pure gastric juice is a
structureless, limpid, and transparent fluid, of
a pale straw colour. Its taste is slightly
saline, and distinctly acid. And it has a pe-
culiar faint odour, which is probably charac-



fDe Prima Coctione, Geneva, 1692), Brugnatelli
(Crell's Ann-ilen, 1787), and John Hunter (Animal
(Economy, 2nd ed. p. 205. 1792) had found that
the stomach contained an acid. Macquart (Memoires
de la Soc. Roy. de Medecine, 1786) stated this
acid to be phosphoric in the paunch of Ruminants.
Treviranus extracted the proventriculus of Birds
with water : he thus, amongst other results, was able
to confirm Hunter's conjecture, and regard it as
lactic acid (Biologie, vol. iv. p. 358. 1814). Chevreul
(Magendie's Physiologic, 1st & 2nd ed. 1825, vol.
ii. pp. 11, 12.) analyzed a fluid obtained by volun-
tary vomiting. He not only confirmed the presence
of lactic acid, but announced the presence of the
muriates of ammonia, potash, and soda; together
with an animal substance soluble in water, but not
in alcohol.

In 1824, Prout led the way to a better knowledge
of this fluid by an analysis of the contents of the sto-
mach in Rabbits during digestion, in which he found
hydrochloric acid and chlorides (Philosophical Trans -
actions, 1824, pt. i. p. 45.). Dr. Children confirmed
this statement from the gastric fluid of a dyspeptic
patient (Annals of Philosophy, 1824, vol. viif. p. 68.).
Leuret and Lassaigne, however, using this latter
method, confirmed Chevreul as to the presence of
lactic acid (Recherches physiologiques et chemiques
pour servir a 1'Histoire de la Digestion. Paris, 1825.)
Tiedemann and Gmelin excited the secretion of
gastric juice by introducing stones into the stomachs
of animals, and found hydrochloric acid on examin-
ing the contents of the stomach after death (Die
Verdauung nach Yersuchen. Leipzig, 1831). In
1833-4, Beaumont's unique case afforded specimens
for three analyses ; by Dunglison, Silliman (Beau-
mont, Op. cit. pp. 69. et seq.), and Berzelius (An-
nuaire des Sciences chemiques, p. 282.). They all
essentially corroborated Prout (Annales de Chemie,
t. lix. p. 348.) ; as did Braconnot in 1835, with gastric
juice from the sponged stomach of animals. \Vas-
mann, in 1839, made some excellent experiments on
artificial digestion with an infusion of pig's stomach ;
but added little or nothing to our knowledge of
the gastric acid (Nonnulla de Digestione. Berolini,
1839). Huenefeld, adopting Prout's method, obtained
lactic acid (Chemismus in der Thierischen Organi-
zation. Leipzig, 1840) ; a result in which, as well as
in the cause of Prout's and Dunglison's view, Leh-
mann either preceded or confirmed him (Physiolo-
gische Chemie, 1840. Bd. i. p. 284.). Enderlin,
however, who examined the digesting stomach of a
beheaded criminal, and repeated Dunglison's process,
reasserted its results (Liebig's Annalen der Chemie
und Pharmacie, 1843. Bd. xlvi., p. 122.) In this year,
Blondlot imitated Beaumont's case, by instituting
fistulas in the stomachs of dogs; and announced
biphosphate of lime as the acid principle (Traite
Analytique de la Digestion. Paris, 1843). Lassaigne
(Journal de Chemie, 1844, pp. 73. 183.) ; and Bernard
and Barreswil (Comptes Rendus, 1844, t. xix. p.1285.)
made use of the same method ; but denied the accuracy
ot'Blondlot's chemical results in detail, and affirmed
the presence of lactic acid. Pelouze corroborated
some of their statements (Comptes Rendus, t. xix.
p. 1227.) ; as subsequently did Thomson also (Philo-
sophical Magazine, 1845, p. 419.). Schmidt next
asserted that the active principle of the gastric juice
was hydrochloric acid, modified by combination
with the digestive principle; but did not detail
the analyses on which this view was based (Annalen
der Chemie u. Pharmacie, 1847, Bd. Ixi. p. 311.).
Lehmann, in 1849, corroborated the lactic acid view,
by examinations of gastric juice from tistulae (Be-
richte der Gesell. der Wiss. zu Leipzig. Bd. i.



teristic for each of the different* species of
animals, like the smell of the blood from
whence it is no doubt derived.

Where, as is often the case, the gastric
juice is mixed with saliva, mucus, or relics of
the food, its appearances will of course differ
from those above described. The froth of the
saliva sometimes distinguishes this admixture.
The mucus thus added is ropy or viscid, and ge-
nerally presents scaly epithelium, which, toge-
ther with its neutral or alkaline character, betray
its origin from the mouth or oesophagus. Both
it and the fragments of food are frequently
deposited from the gastric juice, as a dirty
flocculent sediment. And they may always
be removed from it by careful filtration ; when
the fluid loses its greyish, brownish, or turbid
character.

The specific gravity of the gastric juice was
observed by Silliman to be about 1005*0. But
from the condition of the specimen heexamined,
and the mode of weighing^ he adopted, very
little reliance can be placed on this state-
ment. Lassaigne J also made direct obser-
vations with the same view, and found that
the irritated empty stomach poured forth a
fluid of sp. gr. lOOl'O ; while that secreted on
the contact of flesh was 1005*0, and with bread
lOlO'O. But it must obviously be very difficult
directly to determine the specific gravity of
such a fluid, in the small quantities in which
it is generally obtained. The per-centage of
solid contents is more easily estimated.
Tiedemann and Gmelin rated it at T95 in
the gastric juice of a dog who had been made
to swallow small pieces of limestone ; and at
P6 in that of a horse. Berzelius gives it at
1*27 in the specimen sent him by Beaumont;
Lassaigne at T32, and Blondlot at TO, from
the gastric fistulae of dogs ; Frerichs (appa-

pp. 100. et seq. ; and Op. cit. Bd. i. s. 97.). And
Frerichs about this time came to the same conclu-
sion (Wagner's Handwoerterbuch der Physiologic,
vol. iii. p. 815.) from similar experiments.

But this comparative unanimity in favour of
lactic acid was not destined to last long. In 1851,
Huebbenet for the first time found a simple method
of preventing that admixture of saliva which had
hitherto rendered the gastric juice obtained in such
experiments with fistula? an impure secretion. This
he did by obliterating the ducts of the larger salivary
glands. And the researches which Bidder and
Schmidt instituted upon the gastric juice thus pro-
cured seem at length to have established, that it is
the hydrochloric which constitutes the proper acid of
the gastric juice.

[In preparing the greater part of this essay for
the press, the author found it impossible to procure
a copy of Bidder and Schmidt's valuable Essay ; and
was hence only acquainted with such portions of it
as are mentioned in Lehmann's (Physiologist-he
Chemie, vol. iii.) recent work ; in the reports given
of Huebbenet's Dissertation by Scherer and Valen-
tin, in Canstatt's Jahresberieht (1852, Bd. i.) ; and by
Funke in Schmidt's Jahrbuecher (1851, p. 275.).]

* At any rate the author's observations tend to
show that this is the case in Man and many
animals. Human gastric juice is stated by Dun-
glison (Physiology, vol. i. p. 503.) to smell of
hydrochloric acid. And Beaumont (p. 76.) asserts,
that it tastes like this acid in a state of dilution.

f Beaumont, Op. cit. p. 72.

J Loc. cit. pp. 183. et seq.



330



STOMACH AND INTESTINE.



rently from dead animals) at 1'72, 1'80, M5,
after feeding with hay, bones, and peppercorns
respectively; Lehmann at an average of 1'4 ;
Bidder and Schmidt at 2'694 in the gastric
juice of a dog with deligated salivary ducts,
2'883 in another dog in whom they were free,
and 1-385 from a sheep. These latter high
numbers indicate that, whatever may be the
influence of an admixture of food or saliva in
increasing the residuum of the gastric juice, it
is more than counterbalanced by the loss
which attends the analysis of small quantities.
The first of these three quantitative analyses
by Bidder and Schmidt I have made the ba-
sis of a calculation *, according to which the
specific gravity of the gastric juice would be
1003'3, an estimate that tolerably agrees
with the observations of Lassaigne and Silliman.

The quantity of the gastric juice is even less
accurately established. From Beaumont's
experiments, it would appear that at least
eight ounces may be secreted in an hour.
It is, however, not impossible that ten times
this amount may be poured out during the
digestive process. For Bidder and Schmidt's
observations on animals give an average of
about i^ th of the weight of the whole body
per hour, with a maximum of ^V tn m the
same period. But it is probable that the
latter proportion exceeds that which could be
secreted by a human being f in the same space
of time.

Chemical composition. In inquiring into the
chemical composition of the gastric juice, it
will be convenient successively to consider its
acid, its saline, and its animal constituents.

The gastric acid. Although this obvious
and unmistakeable character of the gastric
juice has been recognised for more than 150
years, yet the nature of the acid on which it
depends is probably still regarded as un-
certain. An impartial and searching criticism
of all the numerous and conflicting analyses
that have been made would far exceed the
limits of this essay: even had the author
(what he has not) the abilities and leisure
necessary to such a task. The reader will
therefore only expect such a sketch, as may
include some of the chief facts which justify
us in preferring, if not in adopting, one par-
ticular view.

Not to mention those exceptional instances
in which acetic, butyric, or other acids, have
been found in inefficient quantity in the con-
tents of the stomach, there are at least three
views of sufficient importance to demand

* This calculation is founded on a method sug-
gested by Schmidt, and quoted by Lehmann (Op.
cit. Bd. iii. pp. 4, 5, 6.). 1 have assumed that the
condensation of the ferment on solution equals that
of albumen ; that the chlorides of calcium and am-
monium stand about midway between those of po-
tassium and sodium in this respect ; and that the
hydrochloric acid occupies no bulk at all. On these
suppositions, the 26'938 grains of residuum would
take the space of 23-617 grains of water ; whence
100023-617 + 26-938 = 1003-3.

f In a person of average weight, the above pro-
portion of ^th of the whole body would correspond
to a secretion of about seven pints (nearly one
gallon) of gastric juice in an hour.



some notice. The first of these regards the
gastric acid as the hydrochloric : the second as
the lactic. While the third attributes the acid-
ulous character of the secretion to the presence
of a salt, the acid phosphate or, as it is some-
times incorrectly termed, the superphosphate*
of lime.

The latter view, which denies the presence
of a free acid, is the more recent of the three. It
rests solely upon the statements of Blondlot f;
from whose writings we select some important
details, which are directly contradicted by the
concurrent testimony of other chemists, and
even by his own later researches. According
to him, the gastric juice is precipitated by
lime, does not act upon chalk, and contains
no chloride of calcium. He also states (or
rather implies) that biphosphate of lime is
decomposed by incineration, so as to leave a
neutral residue. Each of these statements is
met by Lassaigne, Huenefeld, Melsens, Dumas,
Bernard, and various other authorities, with
a direct denial. And in a more recent Memoir,
Blondlot himself lays especial stress upon the
presence of a large quantity of chloride of cal-
cium, the absence of which salt he had previously
insisted on.{ After these remarks, it is un-
necessary to detain the reader by any further
consideration of the various other errors
qualitative as well as quantitative which in-
validate the chemistry of this observer. But
it is impossible to make these necessary allu-
sions to Blondlot's analyses without passing a
tribute to his talent, in devising an operation
to which we owe all the brilliant experiments
that have lately done so much for the physio-
logy of digestion.

Of the two remaining views, the parti-
sans of each were, until lately, so equal in
number, in repute, and in the validity of their
arguments, that few physiologists could decide
in favour of either : and those who could
not suspend their judgment, were probably
beginning to believe in both.

On the side of lactic acid was the united
testimony of Chevreul, Lassaigne, Thomson,
Lehmann, Payen, Bernard, and Frerichs ;
who had all verified its presence in gastric juice,
sometimes when unmixed with food. While
against the analyses of Prout , Dunglison,
Braconnot, Tiedemann, and others in which
hydrochloric acid was either lost from the

* The formula of which is CaO, 2 HO, P2 O 5 .

t Loc. cit.

j Compare Op. cit. pp. 246. 250., and Comptes
Rendus, t. xxxiii. p. 118.

This allusion to Dr. Front's analyses may seem
to require some explanation ; the more so, that they
have sometimes been misquoted. He analyzed the
gastric juice of rabbits who had been fed shortly
before death. The contents of the stomach were