organization there are to be observed:

1. A definite arrangement of the cells to form the tissues. A tissue is a
group of like cells.

2. A definite arrangement of the tissues in the organ. Each organ contains
the tissues needed for its work.

3. In several instances there is a definite arrangement of organs to form
systems.

4. The body as a whole is made up of organs and systems, together with the
structures necessary for their support and protection.

There now remains a further question for consideration. What is the one
supreme end, or purpose, toward which all the activities of the body
organization are directed? This purpose will naturally have some relation
to the maintenance, or preservation, of the cell group which we call the
body.

*The Maintenance of Life.*—The preservation of any cell group in its
natural condition, whether it be plant or animal, is accomplished through
keeping it alive. If life ceases, the group quickly disintegrates and its
elements become scattered, a fact which is verified through everyday
observation. Though the nature of life is unknown, it may be looked upon
as the organizer and preserver of the protoplasm. But in preserving the
protoplasm it also preserves the entire cell group, or body. Life is thus
the most essential condition of the body. _With life all portions of the
body are concerned, and toward its maintenance all the activities of the
body organization are directed_.