1902.] 



On Skin Currents. 



375 



reaction greater than +0-0050 volt to strong induction shocks of + or 

 - direction.* 



Tested by tetanising currents of alternating directions such skin 

 gives to both pairs of directions a similar indubitable positive response 

 of, e.g., 0-0200 to 0*0500 volt. 



Moribund skin and skin obtained from the post-mortem room, from 

 subjects that have died gradually, have generally afforded doubtful 

 results, and by doubtful results I mean a reaction of variable direction 

 and measured by ten thousandths of a volt. 



In all cases the electrodes alone were carefully tested for polarisa- 

 tion, anomalous as well as ordinary, before use and after experiment ; 

 the skin was subsequently killed by boiling and the experiment 

 repeated. 



The course of events will be best set forth by the detailed account 

 of a single observation. 



(Observation 2.) Skin of breast, removed for carcinoma, 1J hours 

 after operation. The single break induction shock of + and - direc- 

 tion gave the response + 0-0180 + 0-0230, the resistance being 

 1 megohm. 



An Illustrative Observation. — To tetanisation of both pairs of direc- 

 tions the responses were + 0*0440 and + 0-0460. R now \ megohm. 

 After boiling the resistance was only 50,000 ohms. 



The next day the reactions of a fresh piece of same skin to strong 

 single shocks + and - were + 0-0050, + 0*0175 volt. On the 4th 

 day the reactions were + 0-0025 and + 0*0035. In all these cases the 

 positive response was abolished by boiling. 



On the 7th day the reactions were doubtful, except in the case of 

 the nipple, where the response to all kinds of excitation was about 

 + 0*0050. In this case the conductivity was increased from 100 to 

 121 by tetanisation. 



Diminution of Resistance. — A remarkable feature noticed in the outset 

 of these experiments was the great diminution of resistance caused by 

 tetanisation. The alteration of resistance was most pronounced in 

 the case of skin which, judging by its response, was most alive ; it 

 was far less noticeable in the case of moribund and doubtful skin ; 

 it was not apparent at all in the case of skin certainly killed by 

 boiling, as might be expected ; however, the resistance of boiled skin 

 was always far below that of the same skin previous to boiling. 



All these points will be most clearly apparent by reference to 



% i. 



The noteworthy points are — 



(1.) The contrast between the four responses of the living and 

 dead skin. 



* Throughout the present paper -t- signifies " outgoing " and — " ingoing," as 

 rpgards direction of current through the skin. 



