ANIMAL AND VEGETABLE 213 



current and transforming, in a shunt-circuit, an afferent 

 to an efferent impulse. The correct number of cells is not 

 shown, but any even number between G and ACC or any 

 uneven number between the sensory nerve-fibre and the 

 motor fibre would do it. 



Halliburton avers that : " The synaptic junctions are 

 naturally the places which the impulse has the greatest 

 difficulty in traversing ; and some observers believe that at the 

 points of contact there is a kind of undifferentiated interstitial 

 protoplasm which the impulse has to get through." * 



Suppose there to be many thousands of such synaptic 

 junctions, or, electrically speaking, many thousands of 

 condensers of varying capacity, concentrated over a length 

 of, say, three feet, and further suppose them to be ulti- 

 mately connected to a copper wire of three feet in length 

 to earth through a high resistance at its further end. Let 

 the condenser-length be from A to B and the wire-length 

 from B to C. Would the velocity of a current of electricity 

 sent from A to B be the same as from B to C ? 

 Obviously it would not, could not, be. 



Going back, after these interpolations, to our diagram 

 of reflex action, the electrical impulse, due to alteration of 

 resistance at S caused by, for instance, a rise or fall of 

 temperature, by pressure upon the skin, etc., would be 

 afferent. Upon reaching the storage cell, G, it would be 

 affected or unaffected by difference or non-difference of 

 potential between sensory nerve-fibre and cell. If the cell 

 held its normal charge, the impulse would pass unaltered 

 (by that cell) on its path to the brain. If, however, the 

 potential of the cell was higher than that of the fibre, the 

 impulse would be increased or accelerated, and vice versa. 

 At the point PCC, the cell there would be in an inductive 



* The italics are my own and are intended to suggest a reason, one 

 reason, for the comparatively very low velocity of the nerve-current as 

 compared with that of electricity along a wire or cable. 



