COLOR SENSITIVITY OF THE PERIPHERAL RETINA. 71 



can a strong case be made out in its behalf. For while it is doubtless 

 true that the periphery possesses less favorable optical conditions, still 

 one can not understand how these can furnish even a partial explana- 

 tion of the visual phenomena which are here to be accounted for. 



(4) The fourth conception is wholly different from any of the 

 others. It represents an attitude of despair, in that its advocate con- 

 fesses his failure to bring his facts into relation with any retinal process 

 which can be conceived in analogy with the phenomena or principles of 

 physics, of physiology, or of chemistry; and feels himself obliged to 

 invoke the aid of a mysterious cerebral or other central process whose 

 nature he also fails to characterize. Such a view as this might win the 

 temporary adherence of the scientist who temporarily despairs of find- 

 ing a more definite or more promising envisagement of the process of 

 color vision ; but it can scarcely hope to be accepted excepting as a tem- 

 porary resting-place, or as a last resort to be chosen when all others 

 fail. Such a view has been suggested by Landolt and Charpentier, and 

 is mentioned as a tentative hypothesis by von Kries. It is too vague 

 and ethereal to offer a promising field for discussion. 



