130 



THE NATURE OF FOVEAL DARK ADAPTATION 



TABLE II. 



Relation between Apparent Illumination, Area of Pupil, and Corrected Illumination. 



Durahon of dark adaptation — seconds 



Fig. 6. Dark adaptation of fovea independent of pupil changes. The points 

 are those in Fig. 4 corrected in terms of Fig. 5. They represent the illumination 

 necessary to stimulate the fovea assuming a constant pupil whose area is 27.1 

 square millimeters. This is the area at 7.1 seconds dark adaptation, and corre- 

 sponds to the first point in Figs. 4 and 6. 



