process, known as _assimilation_, is the appropriation of the food
material by the cell protoplasm. In a sense the storage of fat by
connective tissue cells and of glycogen by the liver cells is
assimilation. The term is limited, however, to the disposition of material
with reference to its final use. Whether all the materials used by the
cells actually become a part of the protoplasm is not known. It is known,
however, that the cells are the places where most of the oxidations of the
body occur and that materials taking part in these oxidations must, at
least, come in close contact with the protoplasm. Assimilation, then, is
the last event in a series of processes by which oxygen, food materials,
and cell protoplasm are brought into close and _active_ relations. The
steps leading up to assimilation are shown in Table II.

TABLE II. THE PASSAGE OF MATERIALS TO THE CELLS
MATERIALS DIGESTION ABSORPTION ROUTE TO STORAGE CONDITION
THE GENERAL IN THE
CIRCULATION BLOOD
Proteids Changed In passing Through the Become a As proteids
into into the portal vein part of the in
proteoses capillaries, to the protoplasm colloidal
and the liver and of all the solution.
peptones by proteoses from there cells.
the action and through the
of the peptones hepatic
gastric and change into veins into
pancreatic the the
juices. proteids of inferior
the blood. vena cava.
Fat Changed In passing Through the As fat in Chiefly as
into fatty into the lacteals to the cells minute oil