On Skin Currents. 



487 



Influence of Excitation of Nerve upon Electrical Eesistance 

 of the Skin. 



Exp. 



Eesistance before 

 excitation. 



Eesistance after 

 excitation. 



1 



2500 ohms 



1000 ohms 



2 



2800 „ 



1400 „ 



3 



2500 ., 



1500 „ 



4 



4300 „ 



2400 „ 



5 



3000 „ 



3000 „ 





4000 „ 



1300 „ 



? 



3900 „ 



1200 „ 



Note. — In all except the 5th experiment, excitation of the nerve gave a large 

 positive response. In the 5th experiment, there was no response and no diminu- 

 tion of resistance. 



7. Atropine injected into the dorsal lymph sac has not in my hands 

 abolished the electrical response of the skin produced by excitation of 

 nerve. But by direct application to the skin the effect of such excita- 

 tion has been promptly abolished. There has at such time been no 

 perceptible alteration of the positive response to direct excitation in 

 either direction. Such direct positive response has been promptly 

 abolished by pencilling the external surface of the skin with a solu- 

 tion of mercuric chloride. In several instances the skin, before ceasing 

 to respond altogether, has manifested a small negative response to 

 both directions of excitation. The reaction is rapidly abolished by 

 HgCLi solution of decimolecular strength, more gradually but com- 



M 



pletely abolished by HgCl 2 = (2*7 per 1000). Prolonged (J hour) 



soakage of the skin in a freshly made 1 per cent, solution of atropine 

 sulphate has produced diminution of the direct response— not much 

 more marked, however, than may sometimes be observed after soakage 

 in normal saline. 



8. The electrical response of the skin to direct electrical excitation 

 is at or near its external surface. This fact is indicated by the result 

 of pencilling with mercuric chloride solution, and conclusively 

 demonstrated by the following experiments : — 



Excitation of the skin through A and B, subsequent lead-off to galva- 

 nometer A and C. A large after-effect is witnessed, from A to C 



