THE VISUAL PIGMENTS AND THEIR PHOTOPRODUCTS 



-^max at about 500 mju, found in four mammals, one bird and three 

 amphibians and the other, with Amax at about 540 m/x, found in fish. 

 The eight species of fish examined by kottgen and abelsdorff 

 were all of the freshwater variety. When wald (1936b) examined 

 three marine fish — the sea robin {Prionotus carolinus) the black sea 

 bass {Centropristes striatus) and the scup {Stenotomus chrysops), he 

 found that the visual pigments and their inter-relations with vitamin 

 A, and retinene, were the same as in the frog. 



1.0 

 .2 0.8 



^ 



•Vitamins A Retinenes 



12 12 



I II I II 



Rhodopsin Porphyropsin 

 i I I 



500 

 Wavelength -ny/ 



600 



Fig. 2.2. Density spectra of rhodopsin and porphyropsin and of their 

 related retinenes and vitamins A. All maxima equated to 1-0 to facilitate 



comparison. 



{Wald, 1939b) 



In a later paper (wald, 1938) these observations were extended to 

 include another marine fish — the killifish {Fundulus heteroclitus), two 

 species of frog {Ranapipiens and R. catesbiand) the rabbit and the rat. 

 The density spectra of visual pigment solutions made from some of 

 these species are shown in Fig. 2.3. The spectra are all approxi- 

 mately the same, having Amax at about 500 m^ (rhodopsin or visual 

 purple, based on retinene and vitamin A). 



In the case of freshwater fish wald (1939b) found that the visual 

 pigment solutions all had Amax at about 522 mp (porphyropsin, or 

 visual violet, based on retinencg and vitamin A2). wald thus con- 

 firmed the general result of kottgen and abelsdorff, namely that 

 there are two kinds of visual pigment, but amended the Amax of 

 porphyropsin from 540 m/< to 522 vap. The density spectra of visual 

 pigment solutions from freshwater fish are shown in Fig. 2.4. 



33 



