An extremely interesting and original ""zoo book"" by the Assistant Director of the National Zoo in Washington, D.C. Mr. Perry is a rarity--a talented fancier who stumbled into zoo work with a consuming interest rather than degrees or field experience. Concerned with all areas having to do with natural equilibrium under changing environments, Mr. Perry zeros in on current zoo practices. He is particularly concerned with the current incapacity of zoos to aid in preserving dwindling species through judicious mating and planning. (Reproduction falters with the use of aging animals and the dispersal of offspring.) He deplores the tendency of zoos to display quantities of species rather than concentrating upon building up quality displays which better answer the needs of animals and the public. Considerable attention is devoted to sparse but fascinating examples of herd exhibits and open-range concentrations. Always aware of practical difficulties faced by zoo administrators, he discusses threats to the animals' survival in captivity--weather, inadequate diet and ""stress."" The animals' need for activity is the most challenging, arguing again for allowing social animals to live in groups, even in symbiotic relationships. Other chapters deal With pertinent matters such as steps taken to stop illegal and cruel traffic in Wild animals, population control, educative ventures, etc. With a world-view round-up, this is a provocative study.