ANIMAL AND VEGETABLE 163 



A practical remedy, if we were dealing with bundles of 

 insulated wires, would be to copper-tape each bundle or 

 put it in a metal tube, so that induced currents could be 

 intercepted by the tape and tube and prevented from 

 reaching the actual conductors, the wires or nerve-fibres. 

 That appears to be the most reasonable view to take of the 

 function of lymph in this case. It is hardly possible to 

 regard it as an insulating substance, despite its tendency to 

 clot and form a " colourless coagulum of fibrin," in view 

 of the more probable explanation I have suggested. 



Again referring to the figure and adhering to our simile 

 of bundles of insulated wires, it will be evident that if we 

 arrange these in a trough and pour melted bitumen around 

 them the bitumen would form an enveloping sheath, 

 corresponding, roughly, to the epineurium. 



We will take, as another example, the core of a sub- 

 marine cable. The conductors of which there are usually 

 eight or more are separated from each other by gutta- 

 percha, and the total insulation is made up of three layers 

 of gutta-percha and three layers of Chatterton's compound, 

 superimposed one upon the other. 



As an instance of what is done in practice I will 

 quote from Herbert's Telegraphy. 



In the telegraph system of the 

 post-office there are, of course, a large 

 number of telegraph and telephone 

 circuits, which by reason of their being 

 in juxtaposition require about the 

 same measure of protection from 



induction as the multifarious fibrillae Fig. 86. SECTION OF 



of the sciatic nerve. A SCKEBNKD CABLE. 



In order to get rid of inductive interference various 

 devices, such as twisting the wires, were tried with more 

 or less success, but the method which has given the best 

 results is thus described by Mr. Herbert : " The conductor 



