Daltonism, or Colour Blindness 57 Defective Form Vision connected with Colour Deficiency due to Disease 138 Definition at different parts of the Retina 11 Enfeebled Spectrum Luminosity 98 Exhibiting Colour Blindness by Colour Discs 74 Extinction and Persistency Curves of Green-Blind Persons 127 Extinction and Persistency Curves of Monochromatic Vision 125 Extinction and Persistency Curves of Red-Blind Persons 127 Extinction of Colour 105 Extinction of Light by the Centre and Periphery of the Eye 114 Extinction of Colour of equal Luminosity 110 Extinction of Light in the Spectrum 109 Eye: Explanation of its Functions 3 Fatigue of the Retina 6, 30 Field of View 10 Fovea Centralis 4 Fundamental Light 34 Green-Blind Person’s Description of the Spectrum, A 64 Green Monochromatic Vision 131 Helmholtz Diagram of Sensations 38 Heredity in Colour Blindness 58 Hering’s Colour Vision Theory 52 Hering’s Theory not tri-chromic 57 Holmgren’s Colour Tests 169 Kœnig’s Colour Sensation Curves 49 Lissajou’s Figures 37 Luminosity of the Spectrum to the Centre of the Eye, the Fovea Centralis, and outside the Yellow Spot 88 Luminosity of the Spectrum to partially Colour Blind 86 Luminosity of the Spectrum to the Colour Blind 81 Luminosity of the Spectrum to the Normal Eyed 78 Malingerers, Detection of 185 Matching Colours by Mixtures of Simple Colours 26 Maxwell’s Colour Equations 202 Maxwell’s Curves for Red Blindness 69 Measurement of Colour Fields 207 Monochromatic Vision and the Spectrum 66 Number of Cones in the Eye 8 Optograms 9