Vlll 



CONTENTS 



PART III 

 THE CHIEF THEORIES OF COLOUR VISION 



The Prismatic Spectrum of Sunlight, showing the positions of the chief 



Fraunhofer lines and wave-lengths . . .... Frontispiece 



The author wishes to make grateful acknowledgment for permission to repro- 

 duce the following iDustrations : 



to the Royal Society for Figs. 68 — 74; to the Royal Society and Messrs 

 Longmans, Green & Co. for Figs. 11, 12, 14, 19—23, 28—33, 40, 41, 49, 61—65; 

 to the Kaiserliche Akademie der Wissenschaft of Vienna for Figs. 5, 60, 66 and 67 ; 

 to the proprietors of the Journal of Physiology for Figs. 2, 3 and 17, of the British 

 Journal of Psychology for Figs. 34 — 37, 42 and 43, of the Philosophical Magazine 

 for Figs. 38 and 39, of Mind for Fig. 75, and of the Zeitschrift fur Psychologic und 

 Physiologie der Sinnesorgane for Figs. 15, 16, 25 — 27, 45, 46 and 50 — 55; and to 

 Messrs Vieweg und Sohn, Braunschweig, for Figs. 1, 6, 7, 13 and 57. 



