162 STUDIES IN ELECTRO-PHYSIOLOGY: 



is not without foundation when we examine the figure in 



detail. 



Let us first unravel a piece of ordinary electric-light 

 " flex." In the centre are a number of fine copper wires 



ferineurutm 



Fig. 85. 



which we will call fibrillae. The first insulating layer is 

 composed of red cotton, and this we will imagine t9 be the 

 endoneurium. The next outer layer is of white cotton 

 (lymph space), while the outer layer or perineurium is of 

 green silk a very highly-resistant material. 



In the illustration given above it will be seen that each 

 bundle of nerve-fibres is encircled by a lymph space lying 

 between two insulating processes (endoneurium and 

 perineurium), and as lymph is alkaline and therefore 

 conductive, another problem is presented for solution. 



What, in this particular instance, is the function of 

 lymph ? 



Suppose the nerve-fibres to be insulated wires connected 

 in a special circuit for a special purpose, and further imagine 

 these wires to run more or less parallel with hundreds or 

 thousands of other wires in different branch circuits, each 

 or all of which would be conveying currents or transmitting 

 impulses in the same or opposite directions. The result 

 would be inductive interference with the fibres of the sciatic 

 nerve, and the impulses transmitted by them would be 

 liable to continued interruption. 



