Contents. Introduction. Acknowledgments. Part I Periodic Distribution of Properties in Chemical Elements and Minerals. Chapter 1. Periodicity in Chemical Elements. The Order in Chemical ElementsTook Over 100 Years to Establish. The Periodicity of Properties. The Mechanism Underlying the Periodicity in the Chemical Elements. Graphic Display of Chemical Periodicity. Numerous Properties Exhibit Periodic Trends. Anomalies Already Exist at the Level of Chemical Periodicity. Chapter 2. Periodicity in Minerals. Mineral Classification in Based on Chemical Hierarchy. The Periodicity of the Elements Has Determined the Periodicity of Properties in Minerals. Structural and Functional Periodicity-Emergence of the SAme Pattern and Proto-Function in Different Mineral Classes. Part II Periodic Distribution of Functions in Living Organisms. Chapter 3. Period Flight. The Preparation of the Graphs Revealing Biological Periodicity. Flight in Insects Arose from Nowhere. Flight Developed Independently at Five Different Times in Biological Evolution. Flight is Both a Structural and a Functional Process. Flight Demands Many More Structures and Functions than the Existence of a Wing. A Series of Similarities Between the Flight of Insects and that of Birds. Comparison Between the Flight of Bats and Birds. Comparison Between the Flight of Pterosaurs and Birds. The Emergence of Flight in Fish Does Not Appear to be Directly Related to the Environment. Flight in Fish. A Wing and a Fin Can be Made With or Without Bones. The Wing of an Insect and that of a Bird Turn Out to be Built by the Same Genes. Characteristics of Flight Periodicity. Chapter 4. Period Vision. Light-Sensitivity is an Integral Part of the Original Cell Construction. Plant Leaves are Mosaics of Microlenses. Comparison Between the Compound Eyes of Insects and the Light-Sensitive Cells of Leaves. Features of Periodicity in Vision. The Type of Eyes Present from the Protozoa to the Early Chordates. Comparison Between the Eyes of Humans and Cephalopods. Vision Within Insects Displays Periodicity. The Independent Evolution of the Eye Vision and Environment. The Insect Eye and the Human Eye are Produced by the Same Type of Genes. General Features of Vision Periodicity. Chapter 5. Period Placenta. Definition of Placenta. Placenta in Flowering Plants. The Placenta in Invertebrates. The Placenta is Present in Fish. The Placenta in Amphibians and Reptiles. The Placenta Does Not Exist or is Rudimentary in Marsupials. The Periodicity of the Placenta. Chapter 6. Period Bioluminescence. Luminescence in Minerals. Chemical Processes Involved in Bioluminescence. The Occurrence of Bioluminescence. Characteristic Features of Bioluminescence. The Periodicity of Bioluminescence. Chapter 7. Period Penis. The Periodicity of the Occurrence of the Penis Similarities Between the Penis of Humans and Invertebrates. Water Performs with Equal Efficiency the Function of Bones and Other Supporting Tissues. The Emergence of the Penis is Not Directly Related to the General Environment or Organism Complexity. Chapter 8. Period Return to Aquatic Life. Water Changes the Configuration of Minerals and Macromolecules. The Plants that Live in Water have Streamlined Forms. The Plants Reveal that No Change in Genetic Constitution is Necessary to Produce a Novel Hydrodynamic Form and Function. Water-Air and Air-Water Transformations in Plants Experimental Demonstration that Water Decides the Leaf Pattern. The Transformations Involved in the Return to Water in Invertebrates are Similar to Those that Occur Later in Higher Mammals. The Conquest of the Land and the Return to Water in Amphibians. Structural and Functional Modifications in Reptiles Following the Transfer to Aquatic Life. The Hydrodynamic Forms and Functions of Birds Derive from Those of Land Relatives. The Return of Mammals to Aquatic Life Occured Several Times and from Different Orders. The Return of the Carnivores to Water: The Seals. The Sea Cows are Derived from the An