COMPARATIVE ANATOLIY 
(scarahaai) and butterflies, have intestines 
ten timas as large as tlie winged insects 
which are produced from them. 
In the dragon-fly (libellula), which is very 
carnivorous, the intestine is not longer tlian 
the body. There is a small but muscular 
stomach. 
The orthoptera (which class contains the 
locusts, &c. well known for their destructive 
powers) have a long and complicated ali- 
mentary apparatus. They have first a mem- 
branous stomach. This is succeeded by an- 
otlier cavity covered internally with scales 
or teetli, and possessing a very thick muscu- 
lar coat ; in short, a true gizzard. Round the 
end of this the caecal processes are attach- 
ed. There is, lastly, an intestinal canal 
differing in length and diameter. 
The alimentary canal runs straight along 
the body in the Crustacea, and is uniform in 
its dimensions, excepting the stomach. 
ON THE LIVER, SPLEEN, AND OMENTUM. 
The spleen and omentum seem to be less 
constantly found in the animal kingdom 
than the liver, and to be in a manner sub- 
servient to the latter yiscus ; which, on the 
contrary, exists in every class and order of 
animals that is provided witli a heart and 
circulating system. 
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. 
Heemskerk’s companions experienced this, 
in the former instance, at Nova Zemlia; 
and Lord Anson’s squadron, in the latter, 
on the coast of Patagonia. 
The liver of mammalia is in general di- 
vided into more numerous lobes ; and the 
divisions are carried deeper into its sub- 
stance, than in the human subject. This is 
particularly the casein the carnivora, where 
the divisions of the lobes extend tlnough 
the whole mass. But , the utility, which 
Monro has assigned to this structure ; viz. 
that of its allowing the parts to yield and 
glide on each other in the rapid motions of 
the animal, carries very little plausibility 
with it. “ Essay on Comparatiye Anatomy,” 
p. 11. 
In many animal? of this class, as the 
horse, the ruininantia, 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 re- 
ceiving the pancreatic duct, in the cat and 
elephant. 
All the quadrumana, carnivora, andeden- 
tata have a gall-bladder. 
Many rodentia, particularly among the 
rats, want it. The tardigrada; the ele- 
phant, rhinoceros, and pecari among the 
pachydermata ; the genus cervus and ca- 
melus among the ruminating animals ; the 
solipeda; tlie trichechus and porpoise also 
want this part. It does not exist in tlie 
ostrich and paiTot ; but is found in all the 
reptiles. Cuvier thinks that it belongs par- 
ticularly to carnivorous animals ; that it is 
connected with their habit of long fasting j 
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. 
The liver of birds is divided into two 
equal lobes. The hepatic duct opens se- 
parately from the cystic ; and its termina- 
tion is generally, but not always, preceded 
by one or more pancreatic ducts, and fol- 
lowed by that of the cystic duct. 
The fundus of the gall-bladder receives 
branches from the hepatic duct, (“ ductus 
hepaticystici”) ; but that tube sometimes 
unites with the cystic, as in the duck. 
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. 
The spleen gradually diminishes in size 
from the mammalia to fishes. In the por- 
poise there are several small spleens, sup- 
plied from the arteries of the first stomach. 
It is always attached to the first, when there 
are several stomachs. 
In birds it is always near the bulbus 
glandulosus, but does not lie constantly 
very close to the stomach in reptiles, as it 
is found in the mesentery of the frog ; nei- 
ther is it very uniformly situated in fishes. 
In the Crustacea the liver is large, and 
consists of blind tubes, opening into the 
commencement of the intestine. It forms 
the soft high flavoured substance of the 
crab and lobster. 
A liver exists in all the moUusea, and is 
very large ; but this class has no gall-blad- 
der. The liver is supplied with blood from 
the aorta, and there is consequently no 
yeua portarum. 
It is a completely mistaken notion, that 
the black fluid of the cuttle fish is its bile. 
The ink-bag is indeed found between the 
two lobes of the liver in the sepia octopus j 
