THE REGULATING MECHANISM 175 



electrical arrangements is helpful, but we 

 must be careful to remember it is only an 

 analogy. Confusion results from introducing 

 words that have a definite meaning to electri- 

 cians, such as resistance. There is no evidence 

 of any such phenomenon in nerve. If, 

 however, we take the analogy of an electrical 

 current, it might be caused to produce light, 

 heat, motion, or the decomposition of water. 

 All would depend on the arrangements at the 

 end of the wire conducting the current. 

 Finally, as a nerve is a sensitive conductor, 

 irritation at any part of its course will always 

 produce the same effect. We may irritate a 

 nerve close to a muscle or far from it, but 

 the result will be a muscular contraction. 

 We may irritate a nerve near the sentient 

 brain, or far from it, but the resultant sen- 

 sation will be the same, only, in this case, 

 the origin of the impulse will be referred by the 

 mind to the beginnings of the sensory nerve, 

 say in the skin of the hand. An illustration 

 will assist the reader. Suppose a telegraph 

 message were transmitted from Glasgow to 

 Edinburgh, and that the clerk in the office in 



