’…aus dreyerley Arten von Membranen oder Molekülen’: George Palmer’s legacy

Abstract

It is 200 years since George Palmer suggested that colour vision depended on three classes of molecule or membrane. The present paper gives an introductory review of what is today known of the opsins, of the genes that encode them, and of the alterations to which they are subject. Several theories of anomalous trichromacy are briefly reviewed.