7. What is the periosteum? Is a bone once removed ever restored? What are the lacunæ? The Haversian canals? Why so called? _Ans_. From their discoverer, Havers. Define a bone. [Footnote: Bone structure may be summarized as follows: A bone is a collection of _Haversian elements_, or rods. An Haversian element consists of a tube surrounded by _lamellæ_, which contain _lacunæ_, connected by _canaliculi_.--DR. T. B. STOWELL.] What occupies the lacunæ? _Ans_. The bone cells (osteoblasts). How do bones grow? 8. Illustrate. How does a broken bone heal? How rapidly is bone produced? Illustrate. Objects of "splints"? Describe how a joint is packed. Lubricated. 9. How are the bones tied together? What is a tissue? Illustrate. Name the three general divisions of the bones. What is the object of the skull? Which bone is movable? How is the lower jaw hinged? Describe the construction of the skull. What is a suture? 10. Tell how the peculiar form and structure of the skull adapt it for its use. Illustrate the impenetrability of the skull. 11. Describe the experiment of the balls. What does it show? What two cavities are in the trunk? Name its principal bones. Describe the spine. 12. What is the object of the processes? Of the pads? Why is a man shorter at night than in the morning? Describe the perfection of the spine. 13. Describe the articulation of the skull with the spine. Why is the atlas so called? 14. Describe the ribs. What is the natural form of the chest? Why is it made in separate pieces? How does the oblique position of the ribs aid in respiration? (See note, p. 80.) 15. How do the hipbones give solidity? What two sets of limbs branch from the trunk? State their mutual resemblance. Name the bones of the shoulder. Describe the collar bone. 16. Describe the shoulder blade. Can you describe the indirect articulation of the shoulder blade with the trunk? Name the bones of the arm. Describe the shoulder joint. The elbow-joint. 17. Describe the wrist. Name the bones of the hand. How many bones in the fingers? The thumb? What gives the thumb its freedom of motion? 18, 19. Name and describe the fingers. In what lies the perfection of the hand? How do the gestures of the hand enforce our ideas and feelings? Describe the hip joint. What gives the upper limbs more freedom of motion than the lower? How does the pressure of the air aid us in walking? Illustrate. 20. Name the bones of the lower limbs. Describe the knee joint. The patella. What is the use of the fibula? Can you show how the lower extremity of the fibula, below its juncture with the tibia, is prolonged to form a part of the ankle joint? Name the bones of the foot. What is the use of the arch of the foot? What makes the step elastic? Describe the action of the foot as we step.