DICHROMATIC VISION 



173 



scotopic luminosity curves. As the intensity increases the divergence 

 increases. At the highest intensity the protanopic maximum is at 

 about 560 /z/z as compared with the normal 615^. Brodhun's 

 deuteranopic maximum is almost identical with the normal. The 

 deuteranopic achromatic scotopic curve is also nearly identical with 

 both the normal and the protanopic, having a maximum at 535 pp. 



Konig emphasises the fact that nothing as to heterochromatic 

 luminosity values can be deduced from the equivalence of colour 

 matches of two individuals, as of course follows directly from the 

 validity of such matches for both normal and dichromatic vision 

 (v. p. 170). 



670650 625 605590575 555 

 BCD 



535 520 505 



490 

 F 



470 



450 



430 



Fig, 



47. Protanopic luminosity curves for different intensities of light, A being the 

 lowest. H the highest. Abscissae, wave-lengths of the prismatic spectrum of gas- 

 light ; ordinates, arbitrary scale. (Konig.) 



Konig's curves agree well with Abney's 1 (Fig. 49). His normal 

 maximum is 585 ju/.i, protanopic 559' 6 up, and deuteranopic 599-6 /JLJJL. 



Polimanti 2 obtained similar results with the flicker method (Figs. 50 

 and 51). The curves show the general resemblance of the flicker 

 periphery luminosity values. The normal maximum is 589 /z/x, the 

 protanopic 565 ^p, and the deuteranopic 606 ^u,. It is noteworthy, that 

 though Polimanti found his flicker and periphery values appreciably 

 different from Nagel's (deuteranope), v. Kries found no appreciable 

 difference between his own and Nagel's periphery values. However this 

 may be explained it is certain that the divergence of the deuteranopic 

 luminosity curve from the normal is less than that of the protanopic. 



Watson 3 has also published a series of observations by the flicker 



1 Abney, p. 279; Proc. Roy. Soc. Land. A, Lxxxm. 1910. 



2 Ztsch. /. Psychol. u. Physiol. d. Sinnesorg. xix. 263, 1899. 



3 Proc. Roy. Soc. Lond. A, Lxxxvm. 404, 1913. 



