tes
material of no further use to the body.

Of the various ingredients of the bile, only the bile salts are of use in
the work of digestion, for they act upon the fats in the alimentary canal,
and aid somehow in their emulsion and absorption. They appear to be
themselves split up into other substances, and absorbed with the dissolved
fats into the blood stream again.

The third function of the liver is very different from those already
described. It is found that the liver of an animal well and regularly fed,
when examined soon after death, contains a quantity of a carbohydrate
substance not unlike starch. This substance, extracted in the form of a
white powder, is really an animal starch. It is called glycogen, or
liver sugar, and is easily converted into grape sugar.

The hepatic cells appear to manufacture this glycogen and to store it up
from the food brought by the portal blood. It is also thought the glycogen
thus deposited and stored up in the liver is little by little changed into
sugar. Then, as it is wanted, the liver disposes of this stored-up
material, by pouring it, in a state of solution, into the hepatic vein. It
is thus steadily carried to the tissues, as their needs demand, to supply
them with material to be transformed into heat and energy.

151. The Pancreas. The pancreas, or sweetbread, is much smaller
than the liver. It is a tongue-like mass from six to eight inches long,
weighing from three to four ounces, and is often compared in appearance to
a dog's tongue. It is somewhat the shape of a hammer with the handle
running to a point.

The pancreas lies behind the stomach, across the body, from right to left,
with its large head embraced in the horseshoe bend of the duodenum. It
closely resembles the salivary glands in structure, with its main duct
running from one end to the other. This duct at last enters the duodenum
in company with the common bile duct.

The pancreatic juice, the most powerful in the body, is clear,
somewhat viscid, fluid. It has a decided alkaline reaction and is not
unlike saliva in many respects. Combined with the bile, this juice acts
upon the large drops of fat which pass from the stomach into the duodenum
and emulsifies them. This process consists partly in producing a fine
subdivision of the particles of fat, called an emulsion, and partly in a
chemical decomposition by which a kind of soap is formed. In this way the
oils and fats are divided into particles sufficien