SOURCES OF TERRESTRIAL ENERGY 



between the phenomena of consciousness and 

 all other phenomena is an impassable gulf, 

 which no future extension of scientific know- 

 ledge is likely to bridge over, it is nevertheless 

 unquestionable both that every change in con- 

 sciousness is conditioned by a chemical change 

 in ganglionic tissue, and also that there is a 

 discernible quantitative correspondence between 

 the two parallel changes. Let us glance for 

 a moment at certain facts which will serve to 

 illustrate and justify these propositions. 1 



Those changes of consciousness which are va- 

 riously classified as thoughts, feelings, sensa- 

 tions, and emotions cannot for a moment go 

 on save in the presence of certain assignable 

 physical conditions. 



The. first of these conditions is complete con- 

 tinuity of molecular cohesion among the parts 

 of nerve-tissue. A nerve which is cut does 

 not transmit sensori-motor impulses ; and even 

 where the continuity of molecular equilibrium 

 is disturbed, without overcoming cohesion, as 

 in a tied nerve, there is no transmission. It is 

 in the same way that pressure on the cerebrum 

 instantly arrests consciousness when a piece of 

 the skull is driven in by a blow, and slowly 

 arrests it when coma is produced by congestion 



1 [See, regarding the immediately subsequent portion of the 

 text, Introduction, § 1 7, where the contrast between Spencer 

 and Fiske, as to the topic here in question, is pointed out.] 



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