1. Introduction.- 2. Environments and Ecosystems: Freshwater and Marine.- 3. Environments and Ecosystems: Soils, Biological Purification Systems and Other Animals.- 4. Autotrophie Nutrition.- 5. Heterotrophic Feeding.- 6. Endocytotic Vacuoles in Digestion.- 7 Metabolic Pathways.- 8. Feeding in the Ciliophora.- 9. Variety in the Mastigophora.- 10. Sarcodina.- 11. Apicomplexa.- 12. Myxozoa, Microspora and Ascetospora.- 13. Inter-relationships in Protozoan Communities.