Contents 



I INTRODUCTION AND METHODS page 1 

 II THE VISUAL PIGMENTS AND THEIR PHOTO- 

 PRODUCTS 25 



III THE PHYSICAL CHEMISTRY OF VISUAL 



PURPLE 60 



IV THE STRUCTURE OF VISUAL PURPLE 96 

 V ISOMERISM AND THE VISUAL PIGMENTS 126 



VI THE HOMOGENEITY OF VISUAL PIGMENT 



SOLUTIONS 158 



VII OTHER METHODS OF STUDYING VISUAL 



PIGMENTS 181 



AUTHOR INDEX 207 



SUBJECT INDEX 209 



"^3811 



