The Organisation of Matter 



Physiological treatises teach that excitability 

 is one of the essential features of living tissues. 

 This excitability, accompanied by other specific 

 features, is presented by the reactions of inorganic 

 matter. A steel spring forced from its position 

 of equilibrium tends to return to it and reacts in 

 its turn on the hand holding it. This is the 

 universal rule of equality of action and reaction. 

 But in the living world things happen differ- 

 ently; we all know that between the nerve, 

 which is excited, and the muscle, which con- 

 tracts, there are many intermediaries, that the 

 causality is indirect, forming, as it were, a chain 

 of many links, but of which we only know the 

 ends. The attempt has even been made to 

 define the character of organic irritability by 

 instancing the disproportion between its effect 

 and its cause. If a gramme weight is allowed to 

 fall on a nerve the resulting contraction may do 

 much more work than the fall of the weight; 

 but there is no lack, in the inanimate world, of 

 cases presenting a similar disproportion. It is 

 sufficient, as M. Leduc has pointed out, to turn 

 a steam valve in order to start a train or to strike 



a match in order to blow up a powder magazine. 



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