76 PHYSIOLOGY 



were it not for help from physics. No visible or chemi- 

 cal or thermal sign measurable or even perceptible is 

 given by the functional activity of nerve. The only 

 change known in it is electrical. This in many of its 

 forms is brief and extremely small. The instruments 

 for its study are delicate and require a highly developed 

 technique. To the study of the speed of travel, the 

 period of duration, the intensity, the direction, and so on, 

 of this electrical sign we owe most of what is known 

 physiologically of the working of the nervous system. 

 It is one of the distinctions of the famous physiological 

 laboratory here in Oxford that it has contributed more 

 than any other to the knowledge of this electrical sign 

 of nerve-action. In doing so it has laid under contribu- 

 tion phenomena from the conductivity of frog's nerve to, 

 on the one hand, the discharging shocks of electric fishes, 

 and, on the other, the nervous discharges of the convul- 

 sions of epilepsy. It has found significant parallel 

 between nerve-action and the inter-connexions between 

 distant organs in plants ; though plants are beings devoid 

 of nervous system in the ordinary sense. 



It is of the highest interest to know what is the 

 relation of this electrical sign to the real function of 

 nerves. Is the real functional activity of nerve a process 

 completely hidden from us except for a by-product, 

 an accessory phenomenon, namely this electrical disturb- 

 ance which happens to be accessible to us in virtue of 

 superior delicacy in respect of our electrical methods 

 of investigation as compared with other methods ap- 

 plicable in this case ? Or is this electrical disturbance 

 the real cardinal action which constitutes the main func- 

 tion which nerve has to perform ? It seems and many 

 have thought it that it may well be the latter, and that 

 the comparative poverty of chemical findings in regard 



