A Treatise on Physiology and Hygiene

[Sidenote: 2. The more delicate the organ? Example in relation to the brain? The eye? The lungs? The services performed by the bones?]

2. The more delicate the organ, the more completely does Nature shield it. For example: the brain, which is soft in structure, is enclosed on all sides by a complete box of bone; the eye, though it must be near the surface of the body to command an extensive view, is sheltered from injury within a deep recess of bone; the lungs, requiring freedom of motion as well as protection, are surrounded by a large case of bone and muscle. The bones serve other useful purposes. They give permanence of form to the body, by {16} holding the softer parts in their proper places. They assist in movement, by affording points of attachment to those organs which have power of motion--the muscles.

[Sidenote: 3. Their shape and size? Of what composed? Possibility of being s