THE FORM AND MAGNITUDE OF THE ELECTRICAL RESPONSE 

 OF THE EYE TO STIMULATION BY LIGHT AT VARIOUS 

 INTENSITIES. By W. Einthoven and W. A. Jolly.^ (From 

 the Physiological Laboratory of the University of Leyden.) (With 

 twenty-five figures in the text.) 



{Received for inMicatio II 29th Sepiemher 1908.) 



CONTENTS. 



I. Historical Introduction 



11. 



III. 



VI. 



ith the Galvanomeler 



Method of Investigation- 



1. General Remarks . 



2. The Arc Light 



3. System of Lenses . 



4. Weakening the Light 



5. The Spectrum 



6. The Movable Screens 



7. The Moist Chamber and Connection of the Eye w 

 Results — 



1. The Form of the Photo-Electric Reaction to Light of Moderate Intensity 



2. The Three Substances ....... 



3. Light of Different Colours ....... 



4. Rhythmical Reaction on Continuous Stimulation . . . . 



5. The Latent Period . . . . 



The Energy of the Stimulation in Absolute Measurement . 

 The Relation between the Energy of the Stimulation and the 

 Energy of the Reaction ...... 



Summary of Conclusions ....... 



P.\rtE 

 373 



379 

 379 

 380 

 384 

 386 

 387 

 388 



389 

 392 

 405 

 405 



406 

 410 



414 

 416 



I. Historical Introduction. 



The following paper gives an account of our study of the electrical response 

 of the frog's eye to light by means of a sensitive and rapidly moving 

 galvanometer. 



Before discussing our own results, it is desirable shortly to pass in 

 review the principal steps by which our knowledge of the retinal currents 

 in the frog has been built iip upon the foundation laid by Holmgren. 



Holmgren 2 found that when light is allowed tt) fall upon the eye of 



• The research was performed during the tenure by one of us (W. A. J.) of a Carnegie 

 Research Fellowship of the University of Edinburgh; 



2 "Method at objektivera effekten af Ijusintryck po retina," Upsala Lakareforenings 

 Forhandlingar, vol. i. p. 177, 1866. Physiol. Untersuch., Heidelberg, Bd. ii. j). 81, and 

 Bd. iii p. 308. 



