The Electrical Response of the Eye to Stimulation by Light 399 



Figs. 11, 12, 13 and 14. — The reaction of the second substance. Dark eye. 

 Absc. 1 mm. =0"2 sec. Ordin. 1 mm. =4 microvolts. Green light. Intensity 

 of illumination =10-^ I^. /, light ; d, darkness. / control curve precedes 

 reactions 11 and 12. The durati^m of lighting increases from fig. 11 to fig. 14. 

 In figs. 11 and 12 the second substance is actina; alone. In fig. 13 the action 

 of the third substance is seen at C, and in fig. 14 also that of the first at A,. 



