to their two constituents, fatty acid and glycerol. The former is
dissolved by the bile to form soap; the latter is readily soluble in
water. These constituents thus dissolved pass through the walls and
recombine in the form of neutral fat droplets, probably during the
passage through the walls, since they appear in this form in the
cells. They pass into the thoracic duct and thence into the blood
stream.

~Absorption of Carbohydrates.~--The carbohydrates are chiefly absorbed
in the form of monosaccharids. This has been proved by introducing
cane sugar or lactose into the blood vessels and getting the greater
portion of it back unchanged by way of the urine. As the
monosaccharids are taken up by the capillaries lining the walls of the
small intestines, they are passed on to the portal vein and carried by
the portal blood into the liver, where they are stored temporarily as
glycogen, and given out to the blood in the form of glucose as needed.
After a meal rich in carbohydrates, the portal blood will be rich in
glucose, while the blood in general circulation contains about the
same amount as usual, about 0.1%.

~Absorption of Proteins.~--The absorption of the products of protein
digestion occurs through the capillary blood vessels and passes on to
the portal vein. The metabolism of protein is more complex than that
of any of the foodstuffs. It is probable that each living cell
contains enzymes which are capable of breaking down the body proteins
with the production of amino acids just as the proteins of the food
are broken down by enzymes of digestion, and according to Sherman "it
is not improbable that protein synthesis also may be brought about by
every living cell."

~The Absorption of Water.~--This does not occur in the stomach, as
was formerly believed, but in the small intestines.

~The Absorption of the Mineral Salts.~--This occurs in conjunction
with the other food material. Some of the mineral salts are much more
soluble than others and are more readily absorbed. The function of the
mineral salts in the body has already been described, and since they
form a part of every tissue and fluid in the body their absorption and
fate in metabolism must be studied with that of the other chemical
combinations.

ABSORPTION IN THE LARGE INTESTINES

The digestion of the food as it is passed into the last portion of the
alimentary canal has been largely completed. However, that part which
has escaped digestion in the