486 



Dr. A. D. Waller. 



have seen a response, positive at first, give place to a negative effect ; 

 and in the case of a mixed response of type II, I have seen a 

 decreasing positive phase with an increasing negative phase. The 

 entire series of responses is strongly suggestive of the theory that 

 each effect is an algebraic sum of two opposite effects. 



The positive effect by indirect excitation through nerve is less 

 enduring than the negative effect. A second is always much smaller 

 than a first positive effect. 



Skin giving a mixed or a negative effect by indirect excitation has 

 nearly always given a pure positive effect in response to direct excita- 

 tion of whatever direction. 



4. The interval of time between excitation of nerve and electrical 

 response of skin is about 2 seconds. 



VoU 



-005 



-004- ^ 



-003- / ^^^^^ 



'002- / ^**""*-***»*^ 



001 - 







.•M.i 





— 1 — I — 1 — 1 — I — 1 — 1 — I I — 1 u 



1 1 I. 1 \ 1 1 1 1 . 1 



, i i i . i i i i 









to 



ao 



sosecs. 



Teta.n: iqoo 



Electrical response of skin of frog's leg to tetanic excitation of the sciatic nerve. 

 (N.B. — The response is ingoing, i.e., " Hermann's variation.") 



5. The electrical conductivity of the skin is greatly augmented by 

 direct excitation. This point is not in itself very remarkable since the 

 alteration might be simply due to electrolysis. But the physiological 

 origin of the change is indicated by the fact that dead skin similarly 

 excited exhibits little or no change and by the fact that 



6. The electrical conductivity of skin is greatly augmented by 

 indirect excitation through nerve. 



