ZOOLOGY. 
membrane has a villous appearance, as in the human sto¬ 
mach. Close to the pylorus there is a glandular substance 
of a conical form, which projects into ihe cavity, the blunt 
end of it resting upon the orifice of the pylorus. This is 
similar to what is met with in the bullock, but still more 
conspicuous. 
The fourth cavity of the camel, corresponds with that of 
the bullock in all the general characters, and resembles it in 
most particulars. It exceeds it in length ; but the plicae are 
so much smaller, that the extent of the internal surface must 
be very nearly the same in both. It differs from it in having 
a contraction in a transverse direction, immediately below 
the termination of the plicated part, which has led both 
Daubenton and Cuvier, to consider these two portions as se¬ 
parate cavities. 
On a comparative view of the stomach of the bullock and 
camel, it appears that in the bullock there are three cavities 
formed for the preparation of the food, and one for digestion. 
In the camel there is one cavity, fitted to answer the purposes 
of two in the bullock ; a second, employed as a reservoir for 
water, having nothing to do with the preparation of the food ; 
a third so small and simple in its structure, that it is not easy 
to ascertain its particular office. It cannot he compared to 
any of the preparatory cavities of the ruminantia, as all of 
them have a cuticular lining, which this has not; we must 
therefore consider it as a cavity peculiar to ruminants without 
horns, and that the fourth is the cavity in which the process 
of digestion is carried on. 
Fig. 16.—A posterior view of the first cavity of the camel’s 
stomach unopened; and an internal view of the second, 
third, and fourth cavities, in their relative situation to the 
first—similar to the view given of the bullock’s stomach, and 
on the same scale : a, the oesophagus-, b b, the coats of the 
first cavity in a distended state; c, the communication be¬ 
tween the first and second cavity ; d d, the muscle running 
along its upper part to terminate in the orifice of the third 
cavity. This muscle, when it acts with its greatest force, 
brings forward the orifice of the third cavity almost close to 
that of the second, and shuts up the cells, so that no part of 
the solid food can pass into them: e e, the rows of cells 
which lorm a reservoir for the water ; f the opening, lead¬ 
ing into the third cavity of the stomach ; g, the third cavity; 
h, the orifice of the fourth cavity ; i i, the longitudinal plica 
of the fourth cavity ; k k, the rugous structure of the lower 
part of the fourth cavity; l, the glandular projection op¬ 
posed to the orifice of the pylorus; m, the pylorus; n, a 
dilatation, or membranous cavity between the pylorus and 
duodenum; o, the duodenum. 
Of the liver in vermes.—Several testacea, particularly 
among the bivalves, have a liver surrounding their stomach, 
and pouring its bile into the cavity of that organ. In many 
snails it occupies the upper turns of the shell. 
A liver exists in all the mollusca, and is very large; but 
this class has no gall bladder. The liver is supplied with 
blood from the aorta, and there is consequently no vena 
portarum. The vermes of Cuvier, and the zoophytes, have 
nothing analogous to this gland. 
Of the liver in insects.—An organ secreting bile, and 
which may therefore be regarded as a liver, is found in such 
animals only of this class as have a heart and system of ves¬ 
sels, viz., in the genus cancer. 
Of the liver in fishes—In many animals of this class, the 
short intestinal canal is surrounded, and, as it were, consoli¬ 
dated with a long liver. Some fishes, which are almost 
destitute of fat in the rest of their body, have an abundance 
of oil in the liver; as, for instance, the skate and cod. It 
is wanting in some few species. The spleen gradually dimi¬ 
nishes in size, from the mammalia to fishes. In the porpoise 
there are several small spleens; supplied from the arteries of 
the first stomach. It is always attached to the first, when 
there are several stomachs. 
Of the liver in amphibia.—The liver in the amphibia is 
universally of considerable size; and in some instances, as 
the salamander, of immense magnitude. In the tortoise the 
liver has a peculiar conformation. It is divided into two 
Vol. XXIV. No. 1676. 
837 
round irregular masses, of which one occupies the right hy- 
pochondnum, and the other rests on the small curvature of 
the stomach. Both are connected by two narrow branches 
of the same structure, into which the principal vessels run. 
In the green lizard, in the geckos, dragons, iguanas, it forms 
only a single mass, flat or convex below, and concave above. 
Its free edge in the dragons has two fossae, which divide into 
three lobes, of which the right is prolonged into a sort of 
tail. In the geckos it has only one fossa, and the right side 
is also longer than the left. In the common iguana it ex¬ 
tends into a long appendix. In the crocodiles and chame¬ 
leons the liver has two distinct lobes. In the latter it has 
also a long appendix. It has but one lobe in the serpent tribe, 
in which it is long and cylindrical. There is but one also 
in the salamanders, but there are two in the frog genus. 
Of the liver in birds.—The liver is much larger in domes¬ 
ticated than in wild birds. It is well-known that the gall¬ 
bladder is wanting in many species of this class, (for in¬ 
stance in the pigeon, parrot, &c.) and sometimes in parti¬ 
cular individuals of a species, which commonly has it, as 
in the common fowl. 
Of the liver, &c. in mammalia.—Animals of the horse 
and goat kind, and some of the cetacea, afford instances of 
the want of this receptacle. 
On the contrary, in some of those which have it, there are 
hepatico-cystic ducts, which convey the bile immediately 
from the liver into this bladder, as in the horned cattle. It 
deserves to be remarked here, as a peculiarity of the liver of 
some four-footed mammalia, which live in or about the sea, 
namely, the polar bear and some seals, that it seems to possess 
some poisonous or noxious qualities when employed for food. 
Mammalia alone possess a true and proper omentum. 
The liver of mammalia is in general divided into more 
numerous lobes, and the divisions are carried deeper into its 
substance, than in the human subject. This is particularly 
the case in the carnivora, where the divisions of the lobes 
extend through the whole mass. 
In many animals of this class, as the horse, the ruminantia, 
the pachydermata, and whales, the liver is not more divided 
than in man. 
The ductus choledochus forms a pouch between the coats 
of the intestine, for receiving the pancreatic duct, in the cat 
and elephant. 
All the quadrumana, carnivora, and edentata have a gall¬ 
bladder. 
Many rodentia, particularly among the rats, want it. The 
tardigrada; the elephant and rhinoceros, among the pachy¬ 
dermata , the genus cervus and camelus among the ruminat¬ 
ing animals ; thesolipeda; the trichecus and porpoise also 
want this part. It does not exist in the ostrich and parrot, 
but is found in all the reptiles. Cuvier thinks that it belongs 
particularly to carnivorous animals ; that it is connected with 
their habit of long fasting, and serves as a reservoir for the 
bile. 
All the mammalia which want it, except the porpoise, are 
vegetable eaters; and most reptiles, which universally possess 
it, live on animal food. (Lemons d'Anat. comp. tom. iv. 
p. 37.) 
The valvular transverse folds of the cystic duct belong 
only to the simiae, besides the human subject. 
The spleen of the ornithorynehus hystrix is composed of 
two lobes; the anterior somewhat long and thick, the pos¬ 
terior broader and thinner. Both run obliquely towards the 
right side to meet at an acute angle in the left hypochon- 
drium. The texture is loose and spongy. See Meckel De 
Ornithorhyncho parndoio, p 46, 
Those capillary tubes which, because they uniformly 
bring fluids into the blood, have been described as a sepa¬ 
rate system—called the absorbent—are not met with as dis¬ 
tinct parts in animals that have no very prdminent circu¬ 
lating organs. They are absent, therefore, or at least imper¬ 
ceptible, in the vermes and insecta. In fishes, they are 
destitute of glands or valves; and they open by two com¬ 
mon trunks into the united system: and in the amphibia, 
though these absorbents are readily injected in the mesentery, 
9B no 
