194 Mr. G. J. Burch. On the Interpretation of [Feb. 11, 



" On the Interpretation of Photographic Records of the Response 

 of Nerve obtained with the Capillary Electrometer." By 

 George J. Burch, M.A., F.R.S., Physiological Laboratory, 

 Oxford. Received February 11, — Read February 20, 1902. 



Preliminary Note. 



Attention is specially directed to the following changes in the terms 

 used to describe the electrical phenomena of living tissues : — 



Old term. New term. 



Negative phase, or first phase... Electro -positive phase, or 



first phase. 



Positive phase, or second phase Electro-negative phase, or 



second phase. 



Galvanometrically negative Positive, electro-positive. 



Galvanometrically positive Negative, electro-negative. 



This terminology has been advocated for some time by Dr. Waller, 

 who drew attention to it at the International Physiological Congress 

 at Turin, 1901, and is now adopted by Professor Gotch and myself as 

 being more in accordance with the phraseology employed by physicists 

 in similar cases. 



In Parts I and II, where the subject is treated from a purely physi- 

 cal standpoint, special terms have been used in order to avoid the con- 

 fusion that might have arisen owing to the different meanings attached 

 by physiologists to certain words used by physicists. 



Thus— 



Bundle = Nerve or Muscle. 



Linear conductor = Nerve-fibre or Muscle-fibre. 



Point of origin = Exciting electrode, &c, or nerve-ending, &c, 



In Part III the ordinary physiological terms are employed. 



Statement of the Problem. 



In previous papers on the capillary electrometer I have shown how 

 it is possible, from the curves obtained by photographing on a rapidly 

 moving plate the excursions of the end of the column of mercury, to 

 ■draw derived curves representing the variations of the difference of 

 potential by which these excursions were produced. 



I have pointed out* that the photographic records obtained when 

 two currents of definite potential difference and opposite in direction, 

 lasting respectively as long as the first and the second phase of the 

 electrical response of muscle, are thrown in succession into the electro- 



* ' Phil. Trans.,' A, vol. 183, p. 100. 



