On Skin Currents. 



175 



If after exact compensation of this normal current a single induction 

 shock is sent through the pad, either in the ingoing or in the outgoing 

 direction, the effect or, properly speaking, the after-effect is in nearly 

 every instance outgoing, as in the case of the frog's skin. The 

 few instances in which I have witnessed an ingoing response have 

 been in the case of fresh skin, taken soon after decapitation, and 

 tested by comparatively weak induction shocks. (I find in my 

 laboratory notes only one instance of a late ingoing response 3 days 

 after decapitation.) In such cases the ingoing response has been of 

 comparatively low voltage, and has given place to an outgoing re- 

 sponse at the end of a few hours. From review of a considerable 

 number of observations I conclude that outgoing response is the rule, 

 ingoing response the exception. I have kept the former under 

 systematic observation up to 60 hours post-mortem, but have found 

 under the conditions of observation that it may disappear at an earlier 

 period from the skin of ill-nourished animals. 



The physiological action of the skin is indicated : 1, by its invariable 

 direction with both directions of excitation ; 2, by its complete aboli- 

 tion after immersion of the skin in hot water. 



A series of responses provoked at short intervals exhibits summa- 

 tion. Tetanisation by alternating induction shocks in both pairs of 

 directions, excites a larger response than that aroused by a single 

 induction shock. 



These several points will be made sufficiently clear by the following 

 experiments and figures : 



Experiment 4. Direct Excitation. Same Cat as that of Experiment 2. 



Large pad cut off and set up between unpolar electrodes 9 hours after 



decapitation. Compensation. Direct Excitation in + (outgoing) and 



- (ingoing) directions. Berne Coil. 8 Leclanche's in primary circuit. 



10,000 units. 



