382 



Dr. A. D. Waller. 



[Mar. 17, 



the high resistances of unboiled skin, not in that of the low resistances 

 of boiled skin, which, however, are of secondary interest. 



The following instance will serve to illustrate the above mode of 

 calculation : — 



Skin No. II. 5 hours after excision. Galvanometer + electrode 

 resistance = 20,000 w. Two or three preliminary tests made. 





Dea. by 

 1/100 volt. 



Resistance. 



5 

 25 

 35 

 115 

 115 



540,000 

 92,000 

 60,000 

 ? 4,500 

 ? 4,500 







(Defl. by 1/10 volt through 1 megohm = 26.) 



and is (with other data) sufficient proof of the statement that fresh 

 skin has a resistance to be measured in hundreds of thousands of ohms, 

 tetanised skin a resistance of tens of thousands, boiled skin a resist- 

 ance of thousands. 



With regard to the cause of this remarkable augmentation of con- 

 ductivity, we are in presence of two possible alternatives : 1st, a 

 " kataphoric " migration of water ; and 2nd, a dissociation of electro- 

 lytes. 



I do not at present see my way to the sharp discrimination of these 

 two possible factors, and can only bring forward considerations that 

 appear to me to show that the second factor — electrolytic dissociation 

 — is a chief cause of the increased conductivity, although no doubt 

 transport of fluid, and indeed in certain cases rise of temperature may 

 contribute to the effect. 



The diminution of resistance is produced in far more marked degree 

 in living skin than in dead skin. It is best produced in consequence 

 of the summated effect of alternating currents ; it is evident in conse- 

 quence of a single strong induction shock. Thus, e.g. (Skin IV) an 

 initial resistance of If megohm, was lowered to 1 megohm after two 

 single induction shocks at 10,000, and to \ megohm after tetanisation 

 at 1000 for two periods of 5 seconds. 



Kataphoric alterations of resistance, as described by du Bois-Eey- 

 mond, are in the sense of an augmentation caused by desiccation at 

 the anode of a strong prolonged galvanic current. And although 

 there can be no doubt that such anodic augmentation has as its 

 counterpart a kathodic diminution of resistance by reason of aug- 

 mented moisture, it is not a priori very probable that the great altera- 

 tion of skin resistance caused by one or several induction shocks is 

 due to predominant kathodic augmentation of moisture. 



