-I-' I -Mr. -I. S. 



Espcrimcnt /3. Sciatic Nerve oj 

 J'i liiniii'ifi/ Operation. 1 cm. of nerve excised. 

 Esnininntion twelve days aft 



Degenerated Sciatic. 



K.M.F. = 0-003 volt. 



After immersion in tap water. 



K.M.F. = 0-025 volt. 



Intact Sciatic. 



K.M.F. = 0-017 volt. 



After immersion in tap water. 



E.M.F. = 0-026 volt. 



It seems highly probable to the author, biased by the simplicity of 

 the "concentration law," that the extreme case studied, namely, the 

 nerve after immersion in tap water, is but an extreme variation of a 

 pre-existing condition in fact, that the internal structures of the 

 nerve form what is to all intents and purposes a stronger aqueous solu- 

 tion of electrolytes than is found in its superficial parts, just such an 

 arrangement of solutions as the character of the resistance and internal 

 pohvisation of nerves has always made probable. 



If this is true, all the arguments which can be adduced to explain 

 the E.M.F. obtained from the extreme case can be transferred, when 

 modified, to the normal condition. 



In this extreme case there is no need to invoke a difference in the 

 distribution of the dissociation phenomena of life to explain the exist- 

 ence of a source of E.M.F. The source is granted as soon as it is 

 determined that solutions of different concentration, such as are 

 present, are asymmetrically placed in the otherwise symmetrical 

 arrangement of solutions connecting the metallic electrodes.* Failing 

 an absolute knowledge of this asymmetry, there are many reasons 

 which make it highly probable ; the anatomical conditions are 

 obviously asymmetrical. 



The mathematical considerations determining the value of such a 

 source have been so perfectly elaborated, and consequently simplified, 

 that the data collected from the examination of a supposed instance, even 

 of a complicated case, can be afforded a criticism of great exactness. 



With a view to such criticism the research is being continued, and 

 for the present the conditions of a possible reversal are sought. 



Throughout the conduct of this research I have been most liberally 

 assisted with information and advice by Professor C. S. Sherrington, 

 F.R.S., and Professor Oliver Lodge, F.R.S., for which I take this 

 opportunity for expressing my gratitude. I have also to thank Mr. B. 

 Davies, Mr. A. Hay, and Mr. \V. H. Derriman for their frequently 

 sought opinions, and Mr. \V. G. Lloyd for practical assistance in some 

 of the experiments. 



* Concentration cells of Jfernst, 'Electrochemistry,' Le Blanc. 



