First published in 1924 as the second edition of a 1915 original, and part of the Cambridge Psychological Library, this book examines the chief theories on colour vision in the light of available facts at the time of publication. In the first section of the book, Parsons discusses the physical, anatomical and psychological bases of colour vision in a variety of eyes. The second part analyses colour blindness. The third and final segment evaluates the various theories of colour vision. This book will be of value to anyone with an interest in the history of science or colour vision.