Opening Remarks.- 1 Vertebrates.- 1.1 Patterns of Golgi-Impregnated Neurons in a Predator-Type Fish Retina.- 1.2 A Comparative Study of the Horizontal Cells in the Vertebrate Retina: I. Mammals and Birds.- 1.3 Neuronal Connections and Cellular Arrangement in the Fish Retina.- 1.4 Golgi, Procion, Kernels and Current Injection.- 1.5 Electrophysiological and Histological Studies of the Carp Retina.- 1.6 Interactions and Feedbacks in the Turtle Retina.- 1.7 Interactions between Cones and Second-Order Neurons in the Turtle Retina.- 1.8 Synaptic Transmission from Photoreceptors to the Second-Order Neurons in the Carp Retina.- 1.9 Retinal Physiology in the Perfused Eye of the Cat.- 2 Arthropods.- 2.1 Adaptations of the Dragonfly Retina for Contrast Detection and the Elucidation of Neural Principles in the Peripheral Visual System.- 2.2 Voltage Noise in Insect Visual Cells.- 2.3 Spectral and Polarization Sensitivity of Identified Retinal Cells of the Fly.- 2.4 Neuronal Processing in the First Optic Neuropile of the Compound Eye of the Fly.- 2.5 Beyond the Wiring Diagram of the Lamina Ganglionaris of the Fly.- 2.6 Mosaic Organizations, Layers, and Visual Pathways in the Insect Brain.- 2.7 Structure and Function of the Peripheral Pathway in Hymenopterans.- 2.8 Neuronal Architecture and Function in the Ocellar System of the Locust.- 2.9 The Resolution of Lens and Compound Eyes.- 3 Molluscs.- 3.1 Ultrastructural Observations on the Cortex of the Optic Lobe of the Brain of Octopus and Eledone.- 3.2 The Question of Lateral Interactions in the Retina of Cephalopods.- 3.3 Hyperpolarizing Photoreceptors in Invertebrates.- 3.4 The Economy of Photoreceptor Function in a Primitive Nervous System.