CHAPTER IV 

 EXCITATION AND CONDUCTION 



We have shown by this study of nerves that living 

 matter must necessarily undergo metabolic activity and 

 that without an increase of this activity protoplasm 

 will not function. In short, to be excitable, the 

 protoplasm must respire, and to be excited, its meta- 

 bolic activity must be accelerated. It has also been 

 demonstrated that the excited state travels along the 

 fiber with simultaneous increase of the metabolism. 

 Although our theme in this little volume is not a 

 consideration of how this state of excitation is trans- 

 mitted, but is rather an analysis of the conditions 

 which characterize the irritable tissue, the relation 

 between these two phenomena is so close that we 

 shall consider certain facts which are directly con- 

 cerned with them. 



The two phases of protoplasmic irritability are 

 excitability and conductivity, or transmission, of this 

 excitation. Since it is very difficult experimentally to 

 produce excitation without conduction, we are accus- 

 tomed to consider the fundamental processes underlying 

 these two processes as probably identical. There are 

 certain facts which are sometimes cited as evidence that 

 these phenomena are not necessarily interdependent. 

 In the case of localized and partial narcosis, for instance, 

 local excitability in the narcotized portion does not 

 disappear simultaneously with conductivity through 



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