m.] 



EXPERIMENT V 



53 



negative galvanisation, and their reversal to positive currents 

 during positive galvanisation. 



I think these points will be best illustrated by the values 

 obtained in some previous experiments of the kind. The values 

 are approximate only, as I did not correct for kick due to the 

 induction shock itself. 



33. Some questions. Our experiments are at an end, and 

 so is the lecturer's hour. But I will tax your patience for five 

 minutes longer and attempt to answer two questions that must 

 have occurred to you as they have to me. How much of this 

 blaze-reaction is due to the retina, and how much to other 

 tissues of the eyeball ? Is the retinal stuff that reacts to light 

 the same as, or different from, the stuff that reacts to an 

 induction shock ? 



I cannot fully or confidently answer either of these 

 questions. I can only give partial and tentative answers, and I 

 do so far less on account of any value that I place on the answers 

 in themselves, than because I believe you will see how the chief 

 value of a question somewhere, somehow we cannot at the 

 outset foresee either where or how may be wrapped up in our 

 very failure to obtain a neat answer. 



At first I thought that the blaze-current was retinal, like the 

 current excited by light. The expression " retinal blaze " 

 obtained currency in the laboratory, and the title of my first 

 paper runs, " On retinal currents excited by light and excited 

 electrically," and the title of my second paper was intended to 

 be " On the ' blaze-currents ' of the Retina," but it soon became 



