Having presumably run out of human organs and systems, Elgin discusses here the damage and the healing processes that occur not only when you break a bone or skin a knee but also when you get a muscle cramp, wart, pimple, bruise, sunburn or bacterial infection. A promising subject, as kids with a certain bent might welcome the chance to research their own afflictions, but Elgin's background briefings on cells, circulation and the like are on topics more extensively covered in numerous other books (some of them her own). She tells very little about any one injury, and the black and white sketches, generally inadequate in terms of extending understanding, are sometimes totally off base. (Why, for example, a page of fingertip whorls, even when the phrase was mentioned peripherally in connection with the healing of cuts?) Skin deep.