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sidered a powerful stimulus, the latter as stimuli of a weaker kind* 

 Certain phenomena of the branches of nerves, dependent upon 

 their connexion with their centres, are said to be producible by 

 electricity, when this connexion is intercepted ; as, if a portion of 

 nerve were removed and an electrical conductor substituted, the 

 phenomena which otherwise occur during the integrity of the 

 nerves may be produced by electricity. This experiment is just 

 as conclusive as former ones; for if electricity is communicated to 

 the muscles, or to the branches of nerves, it matters very little in 

 what way it gets there, whether by means of a conductor or by a 

 common electric shock : here, also, is the parallel of the scalpel ; 

 for the nerves of an amputated limb is totally separated from their 

 centres, yet irritation with a scalpel will produce the contraction 

 of its muscles, &c. But electricity, it is said, will substitute the 

 influence from a centre of nerves in processes of the organic life, 

 as in digestion. Granting the fact (which is, however, extremely 

 questionable), it proves only, as the other facts respecting the same 

 agent prove, that certain properties derived from a nervous centre 

 may be substituted, and consequently that such properties come 

 under the denomination of stimuli. A passion of the mind may 

 produce a temporary diarrhoea; so also may Epsom salts, or 

 rhubarb; yet we should scarcely call rhubarb a human passion. 

 If electricity is life, it should produce the phenomena of life: if it 

 fail of producing one effect of the properties of life, its identity with 

 these properties cannot be admitted, because life in this respect is 

 different from electricity. The most that can be assumed from 

 the facts collected on this subject is, that electricity holds a rela- 

 tion with life; that certain of the properties of life may be substi- 

 tuted by electricity, and in a less degree by other agents, in which 

 cases these properties are regarded as stimuli, or as properties 

 which are common to many substances. 



26. The influence from a centre of nerves produces the con- 

 traction of a muscle; so will electricity: thus far there are proper- 

 ties in common. But the influence from a centre of nerves 

 produces voluntary contraction of a muscle, or modifies its con- 

 traction, in connexion with the mind, and volition: so does not 

 electricity. Life produces secretion, circulation, &c.; electricity 

 will excite life in connexion with the organs of circulation, secre- 

 tion, &c. or it may appear to produce these effects after they 

 have ceased by the first changes incident to death; that is, while 

 certain properties of life remain free to hold a relation with such 

 an external, or such a stimulus: but electricity will not produce 

 these effects when life has entirely ceased, or when all the pro- 

 cesses of the death of the spirit are accomplished, and when those 

 properties forming irritability, and the last to assume their final 

 change, or alliances, have become extinct. Life forms blood from 

 food: so will not electricity in connexion with the same organs, 

 and in the same temperature ; at least this may be presumed* Life 

 maintains itself by assimilation, electricity is produced by different 



