CHAPTER XXXIII 



THE CONDUCTIVITY BALANCE 



Receptivity, conductivity, and responsivity Necessity for distinguishing these 

 Advantages of the Method of Balance Simultaneous comparison of variations of 

 receptivity, conductivity, and responsivity The Conductivity Balance Effect 

 of Na^COg on frog's nerve Effect of CuSO 4 Effect of chemical reagents on 

 plant nerve Effect of CaCL 2 on responsivity Responsivity variation under 

 KC1 Comparison of simultaneous effects of NaCl and NaBr on responsivity 

 Effects of Na.,CO3 in different dilutions on conductivity Demonstration of 

 two different elements in conductivity, velocity, and intensity Conductivity 

 versus responsivity (a) effect of KI (b) Effect of Nal Effect of alcohol on 

 receptivity, conductivity, and responsivity Comparison of simultaneous effects 

 of alcohol (a) on receptivity versus conductivity (b) on receptivity versus 

 responsivity. 



WE know that when any point in a tissue is acted on by 

 external stimulus, it receives the stimulation and is thrown 

 into a state of excitation. This excitation is then conducted 

 along the length of the tissue, and may be made outwardly 

 manifest at some distant point by means of a suitable in- 

 dication such as motile or galvanometric response. There 

 are thus three different aspects of the excitatory effect to 

 be distinguished from each other, namely, first the excita- 

 tory effect at the point of reception of stimulus, which I 

 have elsewhere designated receptive excitability, or simply 

 Receptivity : secondly, the power of transmission of excita- 

 tion, or Conductivity : and thirdly, the excitatory effect 

 evolved at the distant responding region, which I shall 

 henceforth term Responsivity. Though these three aspects of 

 the excitatory reaction are all alike dependent upon the 

 molecular derangement caused by stimulus, it is nevertheless 

 important to consider them separately, since their variation is 

 not always the same under the same circumstances. We 



