404 



Einthoven and Jolly 



curve after a short period of illumination. In fig. 20, where the illumination 

 has la.sted somewhat longer, there is evidence of the conflict between the 

 actions of substances 1 and 2 

 immediately followed by a positive deflection at A^ 



At Bj is seen a negative deflection which is 



Figs. 19, 20, and 21. — Conflict between the reactions of the three substances. Dark 

 eye. Absc. 1 mm. =0'2 sec. Ordin. 1 mm =26 microvolts. White light. 

 Intensity of illumination = "2 Iw. /, light; d, darkness E, control curve. 

 The three curves are from the same eye. The duration of lighting increases from 

 fig. 19 to fig. 21. The darkening reaction is in fig. 19 a descent of the curve 

 Bj ; in fig. 20 a descent Bj followed by an ascent Aj, and in fig. 21 an ascent A). 



In the last figure of the series (fig. 21), where the illumination has lasted 

 longer still, the characteristics of the organ as a light eye, to which 

 condition the eye m\ist attain more and more, appear in the foreground. 

 Thfe darkening eff'ect at A^ here consists of a pronounced positive deflection. 



