LECTURE III 



Plan of this Lecture Electrical Excitation of a Frog's Eyeball Modifica- 

 tion of the Response to Light subsequent to Tetanisation, and during 

 Tetanisation Effects and After-effects of Single Shocks "Blaze- 

 currents" -Polarisation Currents- Electrocution Three Types of 

 Blaze-currents The Effect is greater than its Cause Influence of a 

 Galvanic Current Some Questions The Crystalline Lens. 



22. I propose to consider to-day, and as much as possible 

 demonstrate : 



1. The effects and after-effects of tetanisation upon the 

 eyeball. 



2. The influence of tetanisation upon its electrical response 

 to light. 



3. The influence of light upon the electrical effects of elec- 

 trical shocks. 



4. The effects and after-effects of single induction shocks 

 (and of condenser discharges) upon the eyeball ; and 



5. The influence of galvanic currents on the effects of 

 induction shocks. 



No small undertaking indeed for a single day's work, 

 nevertheless one that we shall hope to meet by aid of a series 

 of simple experiments. Of course I well know that a string 

 of experiments, perfectly successful it may be, but imperfectly 

 explained and understood, has equal value with a string of con- 

 juring tricks, but I take it that by this time you see your way 

 through the apparatus set out on the lecture table and the 

 diagrams hung at your elbow. Moreover, I can refer you to a 

 paper published last year, on the Blaze-currents of the Frog's 

 Eyeball, that contains at greater length than would be suitable 

 for a lecture the results and considerations that we are about to 

 review. I venture to think that the reading of the paper would 



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