THE COMPARATIVE PSYCHOLOGY OF COLOUR VISION 145 



lights of suitable intensity he was able to prove that the Purkinje 

 phenomenon is not shown by fishes. 



Owing to the forward movement of the pigment in the pigment 

 epithelium of fishes when exposed to light they possess a certain amount 

 of physical adaptation. Owing to the absorption by the pigment they 

 are in the photopic condition less sensitive to the violet end of the 

 spectrum. 



Hess used various coloured imitation baits against different back- 

 grounds, and showed that their visibility to the fish depended upon 

 their luminosity and not upon their colour. If the brightness of the 

 grey background corresponded to the achromatic scotopic brightness 

 of the bait it was not seen. 



Hess's results have been criticised by Bauer^, v. Frisch^ and Franz^, 

 without, however, seriously shaking his position. 



Amphioxus. The response of amphioxus by movements to light 

 show that the curve of stimulus values of different homogeneous lights 

 agrees nearly, if not completely, with the luminosity curve for fishes and 

 for the totally colour-blind man, and that the adaptative changes of 

 sensibility to light in amphioxus with its primitive visual organs, nearly 

 resemble those of higher vertebrates. 



CHAPTER III 



THE COLOUR VISION OF PRIMITIVE RACES 



Attention was first drawn to the colour vision of primitive people 

 by Gladstone, in 1858. In his Studies on Homer and the Homeric Age 

 he drew attention to the vagueness of the colour terminology of Homer, 

 and concluded that the ideas of colour at that time must have been 

 different from our own. Ten years later Geiger* came to the conclusion 

 that the colour sense of the ancients must have been defective. Not 

 only in Greek literature, but also in the Indian Vedic hymns, in the 

 Zendavesta, in the Norse Eddas, and in ancient Chinese and Semitic 

 writings there is evidence of the paucity of colour terms, especially in 



1 Ce7itralbl. f. Physiol, xxm. 1909 ; Arch.f. d. ges. Physiol, cxxxni. 7, 1910 ; oxxxvii. 

 1911. 



2 Verhandl. d. Deutsch. Zool. GeselUch. 220, 1911. 



^ Inter nat. Rev. d. ges. Hydrobiol. u. Hydrogr. 1910. 



* Contributions to the History of the Development of the Human Race, p. 48, 1880. 



P. c. V. 10 



