I. BASIC PRINCIPLES OF ECOLOGY 1. The Framework of Ecology. 2. Energy in Ecosystems. 3. Material Cycles in Living Systems. 4. Populations and Communities. 5. Evolution and Ecology: The Emergence of the Ecosphere. II. HOMO SAPIENS IN THE SCHEME OF NATURAL THINGS 6. Energy in Human Affairs. 7. Mineral and Water Resources. 8. Population, Food, and Hunger. III. THE IMPACT OF HUMAN ACTIVITIES ON HEALTH AND THE ENVIRONMENT 9. Air Pollutants and Their Sources. 10. The Effects of Air Pollution. 11. Control of Air Pollution. 12. Water Pollution. 13. Land Use and Land Misuse. 14. Wildlife, Wilderness, and Other Biological Resources. 15. Noise as an Air Pollutant 16. The Problems of Persistent Hazardous Materials in the Ecosphere. 17. Waste Disposal in the Ecosphere. 18. Cancer and the Environment. IV. POINTS OF VIEW 19. Human Institutions: Problems and Solutions. 20. From Problems to Promise: An Assessment. Appendix: Think Metric.