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Now though chemists may solve the 

 cause of these phenomena, physiologists 

 have yet to learn, and probably they 

 never may learn, why certain actions 

 succeed to certain causes in living bodies. 

 Causes which induce muscular or nervous 

 actions in one part do not induce similar ac- 

 tions in another. Both muscles and nerves 

 have peculiar habitudes and modes of action, 

 and require the application of various 

 peculiar excitements. Causes which pro- 

 duce no bad effect upon one person, will 

 have a detrimental influence upon another, 

 and this we say is the result of idiosyn- 

 crasy. Thus the odour of a cat, or the 

 effluvia of mutton, the one imperceptible, 

 the other grateful to the generality of 

 persons, has caused individuals to fall 

 on the ground as though bereaved of 

 life, or to have their whole frame agi- 

 tated by convulsions. Substances which in- 

 duce disease in one person or animal, 

 do not induce disease in others. That 



