J. 

 THE VISUAL PIGMENTS 



by 



H.J. A. DARTNALL 



B.Sc, Ph.D., F.R.I.C. 



Head, Visual Research Division, 



Ophthalmological Research Unit {Medical Research Council), 



Institute of Ophthalmology. 



LONDON: METHUEN & CO. LTD. 

 NEW YORK: JOHN WILEY & SONS, INC. 



