PHYSIOLOGY OF COLOR VISION 455 



TT, inside the color triangle, so that any straight line passing through 

 it will on striking the sides of the triangle join two hues which produce 

 white. This method of finding the complementaries necessarily implies 

 that they must he separated from one another by a considerable dis- 

 tance on the spectrum. For representing these facts a circle instead of 

 a triangle may be employed, and for practical purposes, in the use of 

 colors in painting, such a circle has been found more useful than the 

 triangle. Before we proceed to explain its use, however, it may be well 

 to indicate some of the applications which can be made in art of the 

 facts we have already learned. 



It is in pointilism that this application is most evident. In this 

 method the pigments are laid down in minute areas or spots or lines so 

 that, when the picture is viewed from a certain distance, the different 

 hues act on the same nerve endings of the retina and therefore produce 

 the same effect as if they had been superimposed, as by the use of Max- 

 well's discs. Thus, if a white surface be dotted over with red, green 

 and violet, or any other primary colors, or with red and greenish-blue, 

 or any other complementary colors, the surface at a certain distance 

 will appear grayish white. If, in any of the combinations, one hue be 

 in preponderance of the others the gray will become correspondingly 

 tinted, so that a complete picture may be built up of areas which on close 

 inspection are a mosaic of pure colors but appear at a distance as 

 tinted grays. 



The impressionists, lionet, Segantini, etc., appear to have laid as 

 the basis of their picture a gray at the brightness (or value) which they 

 desired each portion of it to assume. On these surfaces they then ap- 

 plied color more or less pointilistically. The neo-impressionists, such 

 as Seurat and Segniac, on the other hand, went a step further in that 

 the saturation was made to depend entirely on the synthetic principle. 

 They laid on their pigments strictly in dots on a surface which was as 

 nearly pure white as possible. Some of these neo-impressionists had, 

 however, already begun to apply certain of the principles of color 

 apposition in masses which we shall study later. To build up a picture 

 pointilistically must obviously greatly increase the technical difficulties 

 of the artist, especially with regard to outline and form; his freedom 

 of expression is also seriously curtailed. It becomes necessary therefore 

 that very great advantages should be the outcome of such labor. 

 Among the advantages are the sense of atmosphere, the vibrating, 

 scintillating quality of the color areas and the very satisfactory transi- 

 tions at the edges between them, all of which are qualities that can be 

 rendered in no way so satisfactory as by pointilism. 



There can be little doubt that a great part of the peculiar impression 

 produced by pointilism depends upon the slight movements which the 

 eyeballs are constantly undergoing, even during our most intent fixation. 

 This of course produces a certain amount of overlapping of the colors 



