190 



COLOUR VISION 



Dieterrci 1 and Konig and Hitter 2 , Hering 3 , v. Kries 4 , Nagel and May 5 , 

 and Abney and Watson. The maximum luminosity with the gaslight 

 spectrum is about 536 ^, with sunlight about 527 ftp,. The red end is 

 shortened, but not the violet (Figs. 54 and 55). 



90 



80 



60 



50 



30 



2.0 



10 







650 



600 



550 I I 



i 



Fig. 55. 



Achromatic scotopic luminosity curve of a deuteranope. 



Luminosity curve of a monochromat. Abscissae, wave-lengths of the 



prismatic spectrum of the Nernst light ; ordinates, arbitrary scale. (Nagel and 

 May.) 



Whereas, however, increasing the intensity of the light shifts the 

 maximum for the normal towards the yellow (see Section III, Chap, n), 

 it merely increases the luminosity for monochromatic vision. The 

 curve is also independent of adaptation. We have already drawn 



1 Sitz. d. Akad. d. Wiss. Berlin, 805, 1886 ; Ztsch. f. Psychol. u. Physiol. d. Sinnesorg. 

 iv. 241, 1892. 



2 Konig, p. 144. z Arcli.f. d. gcs. Physiol. XLIX. 598, 601, 1891. 



4 Ztsch. f. Psychol. u. Physiol. d. Sinnesorg. xin. 239, 1897. 



5 Ztsch. f. Sinnesphysiol. XLII. 69, 1907. 



