26 COLOR SENSITIVITY OF THE PERIPHERAL RETINA. 



by means of appropriate lenses. An examination of the color sensi- 

 tivity of indirect vision by a similar method resulted in the discovery of 

 a similar state of affairs as regards the " color sense." Albini's method 

 consisted in determining the extreme angular distance at which the 

 colors of a series of stimuli could just be recognized, and in subse- 

 quently redetermining the color limits of the same stimuli when lenses 

 of different refractive powers were interposed. The lens was in every 

 case held obliquely before the eye, its position being such that the visual 

 axis did not pass through it ; the plane of the lens was at right angles to 

 the path of the central ray of colored light coming to the eye from the 

 stimulus-object. This arrangement permitted the fixation-point to be 

 seen by the naked eye, while the stimulus light passed perpendicularly 

 through the lens before it reached the eye. 



The following excerpts from Albini's tables show the general char- 

 acter of his results : 



Albini finds that the extension of the color zone is invariably in- 

 creased by the use of a convex lens, and that the increase of a given 

 color zone is directly proportional to the refractive power of the lens 



