TABLE OF CONTENTS 



B. Photopic Vision 81 



Cone Vision, 81 — Color, 81 — Saturation, 84 — Brightness 

 and the Purkinje Phenomenon, 87 — Trichromatic Vision, 

 88 — Central Events in Trichromatic Vision, 91 — Color 

 Blindness, 96 — Photochemistry of Color Vision, 100. 



5. THE GENESIS OF THE VERTEBRATE EYE . . .104 



A. Embryological 104 



Formation of the Optic Cup, 104 — Differentiation of the 

 Retina, 108— The Lens, 109— The Hyaloid Circulation, 



113 — The Vitreous, 113 — The Vascular and Fibrous 

 Tunics, 114 — Lids and Glands, 117 — -Variations in Non- 

 Mammals, 117. 



B. Evolutionary 119 



The Eye a 'Part of the Brain', 119 — Early Theories, 120 — 

 Balfour's Theory, 122 — The Placode Theory, 125 — Bo- 

 veri's Theory, 125 — Studnicka's Theory, 126 — Origin of 

 the Retina, 128— Origin of the Lens, 129. 



6. ELEMENTS OF VERTEBRATE PHYLOGENY . . .134 



Part II — Ecologic 



Chapter ^ Page 



7. ADAPTATIONS TO ARHYTHMIC ACTIVITY . . 143 



A. The Twenty-Four-Hour Habit and the Eye . . 143 



B. Retinal Photomechanical Changes . . .145 



Pigment Migration, 146 — ^Visual-Cell Movements, 147 — 

 Significance and Distribution, 149 — Immediate Causation, 

 151. 



C. Pupil Mobility 153 



Functions of the Pupil, 153 — Pupillary versus Retinal 

 Adaptation, 154 — Comparative Survey of the Two Meth- 

 ods, 158. 



D. DuPLiaTY and Transmutation 163 



8. ADAPTATIONS TO DIURNAL ACTIVITY .169 



A. DiuRNALiTY AND THE Eye 169 



Diumality and Sharp Vision, 169 — Diurnality, Acuity, 



and Food, 169— The Eye as a Whole, 171. 



B. The Diurnal Retina 175 



Cone: Rod and Receptor: Conductor Ratios, 175 — Minimiz- 

 ation of the Physiological Scotoma, 178. 



