374 



Dr. A. D. Waller. 



[Mar. 17, 



The integration of F and G when m < 1 is troublesome, but when 

 m is sufficiently small, we may without much error neglect G, and 

 integrate F from to ar/2. 



77/- 



tt/2 



2 5 



c(c -m) 4 log 

 o 



94 



v 



a m 19 m 2 16 ra 3 



4 c 2 3 c 3 



'3 8 , 19 9 16 , 



Adding (E) and (M) we obtain 



..)dB 



(M). 



9 9 9 /2 B 2io-i6 2 /2Bno- 



- 7T 2 ft 2 m 2 = ll'l (2% 2 *^ 



" On Skin Currents.— Part III. The Human Skin." By Augustus 

 D. Waller, M.D., F.E.S. Beceivecl March 17— Read April 

 24, 1902. 



(From the Physiological Laboratory of the University of London.) 



The purport of the following observations was to examine on human 

 skin the electrical reactions described in previous communications in 

 the case of frog's skin, and in that of the cat's skin. 



The Main Facts. — The phenomena are in the main similar under 

 similar conditions, viz., in the case of a freshly removed healthy skin 

 obtained from the operating theatre, the normal current is always 

 ingoing, and the normal response is always outgoing.* 



In a series of observations — with values noted for an ingoing 

 current of between 0'0020 and O0200 volt — the response has appeared 

 to be quite independent of the magnitude of normal current, and to 

 strong stimulation has usually been from O0100 to O0400 volt. 



As in the case of the frog's skin, the response to single induction shocks 

 has been in the positive or outgoing direction, to both directions of 

 exciting current. Tetanising currents (make and break induction 

 shocks of alternating direction at a frequency of about 60 per sec.) give 

 therefore a summated positive effect. At the outset of my experiments 

 on human skin I encountered doubt and difficulty by reason of the fact 

 that I set myself the difficult problem of determining as far as possible 

 its duration of survival, and by so doing had to deal with cases where 

 a reaction of low voltage is apt to be masked by admixture of 

 polarisation currents. In my experience, healthy skin from the 

 operating theatre, tested within 48 hours after operation, has always 

 manifested indubitable signs of life, and by indubitable I mean a 



* ' Eoy. Soc. Proc.,' 1901, vol. 68, p. 480; vol. 69, p. 171. 



