t remain in the body _permanently_, but only so long
perhaps as is necessary for them to give up their energy, or serve some
additional purpose in the ever changing protoplasm. The excretory organs
then remove from the body a quantity of material that is equal in weight
to the materials absorbed by the organs of digestion and respiration. This
is estimated for the average individual to be about five pounds daily. The
passage of waste from the body is summarized in Table III.

TABLE III. THE PASSAGE OF WASTE MATERIALS FROM THE BODY
Materials State How Formed Condition in How Removed
in the Body the Blood from the
Blood
Carbon Gas By the Dissolved in Separated
dioxide oxidation of the plasma from the
the carbon and in loose blood at the
of proteids, combination alveoli of
carbohydrates, with salts the lungs
and fats. in the and then
blood. forced
through the
air passages
into the
atmosphere.
Urea Solid By the Dissolved in Removed by
oxidation in the plasma. the
the liver of uriniferous
nitrogenous tubules of
compounds. the kidneys
and to a
small extent
by the
perspiratory
glands.
Water Liquid By the As water. Removed by
oxidation of all the
the hydrogen organs of
of proteids, excretion,
carbohydrates, but in the