2. _The fat_ is stored for the most part in the connective tissue. Certain
of the connective tissue cells have the property of taking fat from the
blood and of depositing it within their inclosing membranes (Fig. 79).
When this is done to excess, and the cells become filled with fat, they
form the so-called _adipose tissue_. Most of this tissue is found under
the skin, between the muscles, and among the organs occupying the
abdominal cavity. If one readily takes on fat, it may also collect in the
connective tissue around the heart. The stored-up fat is redissolved as
needed, and enters the blood, where it again becomes available to the
active cells.

3. _The proteids_ form a part of all the tissues, and for this reason are
stored in larger quantities than any of the other food substances. The
large amount of proteid found in the blood may also be looked upon as
storage material. The proteids in the various tissues are spoken of as
_tissue proteids_, and those in the blood as _circulating proteids_. The
proteids of the tissues serve the double purpose of forming a working part
of the cell protoplasm, and of supplying reserve food material. That they
are available for supplying energy, and are properly regarded as _storage
material_, is shown by the rapid loss of proteid in starving animals. When
the proteids are eaten in excess of the body's need for rebuilding the
tissues, they are supposed to be broken up in such a manner as to form
glycogen and fat, which may then be stored in ways already described.

*General Facts Relating to Storage.*--The form into which the food is
converted for storage in the body is that of _solids_--the form that takes
up the least amount of space. These solids are of such a nature that they
can be changed back into their former condition and, by dissolving,
reenter the blood.

Only energy-yielding foods are stored. Water and salts, though they may be
absorbed in excess of the needs of the body, are not converted into other
substances and stored away. Oxygen, as already stated (page 108), is not
stored. The interval of storage may be long or short, depending upon the
needs of the body. In the consumption of stored material the glycogen is
used first, then as a rule the fat, and last of all the proteids.

*Storage in the Food Canal.*--Not until three or four hours have elapsed
are all the nutrients, eaten at a single meal, digested and passed into
the body proper. The undigested food is