PHYSIOLOGY. 
its nerves entirely obstructs digestion. It 
sympathises most remarkably both with 
the constitution at large, and with particu- 
lar organs. 
The chyme, or semifluid substance, into 
which the action of the stomach reduces 
the food, is propelled by the muscular 
power of that bag into the duodenum, 
where it undergoes new changes, particu- 
larly from the admixture of other animal 
fluids, the bile and pancreatic juice : and 
this process is termed chylification. 
The secretion of the pancreas seems to 
bear a considerable analogy, both in its 
nature and ofSce, to the saliva and gastric 
juice. It is very difficult to procure it in a 
pure and unmixed state from a healthy ani- 
mal, but the facts which we hitherto pos- 
sess, shew that its properties are very like 
those of saliva. It is poured into the duo- 
denum by the contractile power of the pan- 
creatic duct : and its secretion, like that of 
the salivary glands, is said to be promoted 
by the pressure of the stomach in its filled 
state; and by the stimulus of the chyme and 
bile on the orifice of its duct. 
The bile is the fluid furnished by the 
liver, the largest viscus of the human body, 
whose importance in the animal economy 
is evinced by its large apparatus and com- 
plicated distribution of blood-vessels, as 
well as by its constantly existing in all ani- 
mals which have a heart. 
The source of the bile has been question- 
ed, whether it be secreted from the hepatic 
artery, or vena portarum f The analogy of 
other secretions, which are all made from 
arteries, favours the former opinion; but 
the blood of the vena portarum seems to be 
the fittest, from its nature, for the secretion 
of bile. The hepatic artery probably serves 
to nourish the liver, as the lungs are nourish- 
ed by the bronchial artery. The distribu- 
tion of the vena portarum is like that of an 
artery. If we suppose the hepatic artery 
to furnish the bile, the excretory duct would 
be disproportionately large. 
The bile, when secreted, passes by a slow 
but constant stream through the hepatic 
duct ; but a greater or less portion is con- 
veyed by the cystic duct into the gall-blad- 
der, in which it is accumulated, as in a 
reservoir, and undergoes certain changes of 
properties, which make it cystic bile. The 
biliary fluid probably flows directly into 
the intestine, while the assimilation of the 
food is going on; and, when the empty 
state of the duodenum causes the end of the 
ductus communis choledochus to be com- 
pressed by its muscular coat, it regurgitate* 
into the gall-bladder. 
There is no direct communication be- 
tween the liver and gall-bladder, and con- 
sequently no other way for the bile to enter 
that bag, except by the cystic duct. The 
hepatic bile is a thin fluid, of a clear orange 
colour, and slightly bitter; the cystic is 
viscid and tenacious, intensely bitter, and 
very dark coloured. The bile, thus chang- 
ed by its residence in the gall-bladder, is 
expelled by the contractile powers of the 
gall-bladder and cystic duct into the ductus 
communis, and thence passes to the duode- 
num. This bladder absorbs the watery 
parts of the hepatic bile, and adds a mucous 
secretion to it. 
The chemical analysis, and the uses of 
the bile are considered under that article. 
Function of the Spleen. The situation aud 
attachments of this organ lead us to suppose 
that its uses are in some way connected 
with the functions of the stomach; yet there 
is nothing more than conjecture to be offer- 
ed on this subject. The removal of the 
part has been performed in dogs without 
a^ material injury to the animal. Its size 
differs according to the quantity of blood 
contained in its cells. Physiologists have 
stated, that its blood possesses peculiar pro- 
perties ; that it is more fluid, does not coa- 
gulate, nor separate readily into serum and 
crassameutum ; is more livid, and possesses 
a greater quantity of carbon. As tiiis blood 
goes to the liver, and as the part possesses 
no excretory duct, it has been argued that 
its function is subservient to that of the 
liver, in imparting to the blood those pro- 
perties which fit it for the secretion of bile. 
By others, the spleen has been regarded 
as a sponge, swelling with blood when the 
stomach is empty, and squeezed out by the 
pressure of the stomach when that organ 
is full. Thus, it is said, more blood will go 
into the stomachic arteries when the secre- 
tion of the gastric juice is going on, and the 
superfluous part in the inactive state of the 
stomach will distend the spleen. 
Action of the small Intestines. The chyle, 
formed in the duodenum, passes through the 
tube of the small intestine, which is the 
organ for absorbing its nutritive parts. The 
description of this fluid will be found under 
the article Chyle. Its progress through 
the intestine is retarded by the numerous 
convolutions of the tube ; and the chyle, 
separated from the excrementitious part of 
the food, is brought into contact with the 
inltaling orifices of tho lacteals, that com- 
