ANIMAL 1:L1-:CTRRITV. LECTURE V. 12 1 



all measure with the more enduring vitality of cold- 

 blooded as compared with that of warm-blooded 

 animals. 



Turning our attention to the extrapolar or electro- 

 tonic effects, which are, as you have just seen, the 

 most obvious evidence of electrolytic polarisation 

 within the nerve, we shall speedily find ourselves 

 confronted by some paradoxical results. We obtain, 

 as you see, extrapolar currents that are equal and 

 opposite on the side of the Anode and of the Kathode 

 respectively, instead of greater on the side of the 

 Anode than on that of the Kathode as in the case of 

 frog's nerve. Of course you think of ordinary current 

 diffusion, but the extrapolar effects are not due to 

 ordinary current diffusion, for they are abolished by 

 crushing the nerve betw^een the leading-in and leading- 

 out electrodes, or by dipping into hot water either the 

 end of the nerve that lies on the leading-in electrodes, 

 or the end that lies on the leading-out electrodes. wSo 

 we put the effects down in the category of physio- 

 logical phenomena, and proceed to test them by 

 anaesthetic vapours, which as you remember produced 

 unmistakeable modifications of the extrapolar currents 

 of frog's nerves. The result is a little surprising and 

 by no means satisfactory ; the anaesthetics with which 

 we are most familiar — ether, chloroform, carbonic acid 

 —do not modify the extrapolar effects in the least. 



And there the matter must stand for the present 

 as regards isolated mammalian nerve. No negative 



