Patent (Children Save the Rain Forest, p. 903, etc.) stresses the importance of protecting the planet's rich gene pool for the survival of all species, and makes clear that seemingly insignificant species may provide medicines and products of great usefulness. With plants and animals in tropical Costa Rica and the more temperate US as models, Patent demonstrates how life forms evolve, adapt, and become extinct. She describes the natural forces of evolution and the threat posed by people. Readers learn of the private and public efforts to catalog and conserve plants and animals, e.g., Costa Rica's National Institute of Biodiversity, a government program that trains local people to collect and categorize specimens. Although Patent mentions the government agreements with drug companies that encourage exploration in exchange for a percentage of the profit when useful substances are identified, there is no discussion of the ethical considerations. The many handsome, full-color photographs are not always well placed and sometimes are only marginally related to the text. Still, this is an attractive and personal discussion of an important issue.