rstrained condition of the ligaments
surrounding a joint, frequently requires very careful treatment. When the
sprain is at all serious, a physician should be called. Because of the
limited supply of blood to the ligaments, they are slow to heal, and the
temptation to use the joint before it is fully recovered is always great.
Massage(82) judiciously applied to a sprained joint, by bringing about a
more rapid change in the blood and the lymph, is beneficial both in
relieving the pain, and in hastening recovery.

*Summary.*--The skeleton, or framework of the body, is a structure which is
movable as a whole and in most of its parts. It preserves the form of the
body, protects important organs, and supplies the mechanical devices, or
machines, upon which the muscles act in the production of motion. The
skeleton is adapted to its purposes through the number and properties of
the bones, and through the cartilage and connective tissue associated with
the bones. The places where the different bones connect one with another
are known as joints, and most of these admit of motion. The preservation
of the natural form of the skeleton is necessary, both for its proper
action and for the health of the body.

*Exercises.*--1. State the main purpose of the skeleton. What is the
necessity for so many bones in its construction?

2. How may the per cent of animal and of mineral matter in a bone be
determined?

3. What properties are given the bones by the animal matter? What by the
mineral matter?

4. Locate the bone cells. What is their special function?

5. State the plan by which nourishment is supplied to the bone cells in
different parts of the bone.

6. Give the uses of the periosteum.

7. State the purpose of the Haversian canals. Of the canaliculi.

8. Give functions of the spinal column.

9. Name the different materials used in the construction of a joint and
the purpose served by each.

10. Name four mechanical devices, or machines, found in the skeleton and
state the purpose served by each.

11. Name one or more of the body machines not located in the skeleton.

12. Of what advantage is the peculiar shape of the lower jaw? Of the ribs?
Of the bones of the pelvic girdle?

13. State the importance of preserving the natural form of the skeleton.
How are unnatural curves produced in the spinal column?

14. How may slight deformities of the skeleton be corrected?

15. What different systems are employed in the bo