_The Animal Body in Life takes_:

1. Food: vegetables and flesh, both combustible.

2. Water for circulation.

3. Air for respiration.


_And Produces_:

4. A steady animal heat, by slow combustion, of 98°.

5. Expired breath loaded with carbonic acid and watery vapor.

6. Incombustible animal refuse.

7. Motive force of simple alternate contraction and relaxation in the
muscles, which, acting through joints, tendons, and levers, does work of
endless variety.

8. A deficiency of food, drink, or air, first disturbs, then stops the
motion and the life.


Carrying out this analogy, you will at once see why a person working hard
with either body or mind requires more food than the one who does but
little. The food taken into the human body can never be a simple element.
We do not feed on plain, undiluted oxygen or nitrogen; and, while the