166 



Dr. N. H. Alcock. 



[Apr. 9, 



Observations and Deductions. 

 It is to be observed that in these experiments there is no ambiguity (such 

 as is possible in the case of nerve) as to the action of chloroform. Neither 

 an increase or decrease of potential occurs (neglecting for the moment the 

 very small residual effect noted above) when the drug is applied to the 

 electrode B, in contact with the inner surface of the skin ; this spot is there- 

 fore acting merely as a moist conductor. When the CHCI3 is applied to the 

 electrode A, which touches the external surface, the current is abolished. It 

 is a necessary consequence that the apparatus giving the current is located at 

 this spot. 



This conclusion is in accord with all the classical observations on the 

 resting current (see the authors quoted above) ; the only other observation 

 that it is necessary to mention here is that of Waller* on the " blaze " 

 current. Using the ABC method, he found that the seat of the electro- 

 motive effect was accurately localised at the spot on the external surface 

 touched by the electrode, and that the opposite spot on the internal surface 

 was quite inert. Although one cannot at the present time define exactly the 

 relations existing between these " blaze " currents and the " resting " currents, 

 there is no doubt that there is a close connection between them. 



Outer 

 surface 



Inner 

 su rf&ce 



Fig. 4.— Diagram of Electrical Mechanism in the Skin of the Frog. 



It is possible to make further deductions from the present experiments. If 

 a diagram (fig. 4) be constructed to reproduce the observed phenomena, it 

 must present the following features : — 



(i) A series of separate cells placed side by side. 



(ii) The positive elements (e.g., zincs) lie towards the outer surface, the 

 negative (e.g., carbons) lie towards the inner. 



(iii) The negative elements are connected with each other. 



(iv) The positive elements are insulated. 



* Waller, loc. cit. 



