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many physiological facts, while there is nothing to discourage 

 the hope that we may in time sufficiently understand the 

 conditions of voltaic phenomena to render the truth of the 

 hypothesis amenable to observation and experiment."* By 

 adducing in its favour such a statement as that about the 

 resemblance of the beating of a brain to a voltaic shock, 

 Mr. Mill upsets his favourite hypothesis, for it is certain that 

 if there be any resemblance between a brain and a voltaic 

 pile it is not of the kind implied. 



But it may be that each little brain cell with its con- 

 nected fibres in some way resembles a minute voltaic battery 

 with its wires \ the matter of which the cell is composed 

 undergoing chemical change, in the course of which slight 

 electrical currents are developed. These being transmitted 

 by the fibres ramifying to different parts exert an influence 

 upon distant tissues and organs among which they ramify. 

 In this case some further arrangement is required by which 

 the action of particular cells and fibres is determined or 

 prevented. Perhaps the closest analogy we can draw 

 between cerebral action and that of an electrical battery is 

 the following : We may suppose in the brain multitudes 

 of minute active galvanic batteries with their delicate con- 

 ducting wires or threads ramifying over extensive tracts 

 of tissue, the action of which is determined by the currents 

 traversing the wires. Situated among these wires or threads, 

 we may suppose little bodies intimately connected with one 

 another which are capable of undergoing alterations in form 

 like the amoeba, white blood-corpuscle, and other forms of 

 living germinal matter. Not the slightest movement, though 

 * Mill's "Logic, "p. 18. 



