dition to connecting the
cells, supplies to certain tissues important properties, such as the
elasticity of cartilage and the stiffness of the bones.

*Nature of the Body Organization.*--The division of labor carried on by the
different organs, as shown in the preceding chapter, is in reality carried
on by the cells that form the organs. To see that this is true we have
only to observe the relation of cells to tissues and of tissues to organs.
The cells form the tissues and the tissues form the organs. This
arrangement enables the special work of different kinds of cells to be
combined in the work of the organ as a whole. This is seen in the hand
which, in grasping, uses motion supplied by the muscle cells, a
controlling influence supplied by the nerve cells, a framework supplied by
the bone cells, and so on. The cells supply the basis for the body
organization and, properly speaking, the body is _an organization of
cells_(5) (Recall the definition of an organization, page 10.) In this
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_.

*The Nutrie