I 



1 



& Z.O 



N 



/.o 



/o 



20 



JO 



yf-O 



Time — /^inutes 



Fig. 6. Dark adaptation of Dr. Simon's eyes, determined by Piper. Simon's 

 vision is that of a normal Trichromat. 



S.O 



I 



V 



5 



J.0 



2.0 



t.O 



/o 



ZO 



30 



-*o 



7? me — f^/'nutes 



Fig. 7. Adaptation experiment with Mrs. Ladd-Franklin ^s subject. Normal 



trichromatic vision. Piper's data. 



511 



