1906.] The Action of Anaesthetics on Living Tissues. 167 



From the experiments in Series I, the postulate (ii) follows immediately ; (i) 

 and (iv) are necessary in this way. CHCI3 abolishes the potential difference 

 between the outer and inner surfaces, and renders that portion of the tissue 

 isoelectric. If the whole outer surface was in electrical connection, the 

 rendering isoelectric of any one part would cause a short-circuit there, and so 

 diminish the current between any other point A on the outer surface and any 

 point B on the inner surface — the experiments in Series I show that this is 

 not the case. Series II confirms this conclusion. CHCI3 to BC abolishes the 

 potential difference there ; it leaves unaffected AB, and the potential between 

 A — C (in parallel) and B is diminished by an amount dependent on the 

 relative resistance between A, B, and C. For a little distance inwards, 

 therefore, the outer surface of the skin has a very high longitudinal resistance. 



The postulate (hi) follows in a similar manner. Further, as the skin as a 

 whole is a good conductor, and as the outer surface is a bad conductor, the 

 inner surface must be a good conductor. As the negative elements are 

 in connection with this tract, they are in connection with each other. 



It is not yet possible to say what elements in the skin act in the manner 

 of the (ZnC) cells in the diagram (fig. 4), still less the exact nature of the 

 action. Certain parts of the frog's skin give an alkaline reaction, others an 

 acid, and the relations between the secretion and the resting current (still 

 more the variations on excitation) are yet to be determined.* But if one 

 regards (for the sake of simplicity) only the glands, one can make a tentative 

 picture of the process (fig. 5). The whole gland will resemble one cell in the 



Direction of current. 



Outer su rf ace 



Inner surface 

 Lymph 



Fig. 5. — Tentative Diagram of Frog's Skin. For simplicity, the membrane (or part of 

 the cell) has been drawn as permeable to - ions. In reality the conditions are more 

 complex. 



diagram. As the carbons in fig. 5 are connected together and with the inner 

 surface, so the lymph must bathe the inner surface of the gland and freely 

 enter the cells of the gland. Now if the outer part of these cells — possibly 



* See Bayliss and Bradford, loc. cit. ; also Hermann, ' Pfluger's Archiv,' 1878, vol. 17, 

 p. 291. 



