116 NERVOUS SYSTEM. 



ished, and this condition has been called anelectrotonus/ 

 Near the cathode, the excitability is increased, and this con 

 dition has been called catelectrotomis. 2 



These varied phenomena have been the subject of ex- 

 tended investigation by electro-physiologists ; and 'although 

 they are not to be ranked among the physiological properties 

 of the nerves, they have considerable pathological and thera- 

 peutic importance. It is well known, fur example, that elec- 

 tricity is one of the most efficient agents at our command 

 for the restoration of the functions of nerves affected with 

 disease ; and the constant current has, particularly of late, 

 been extensively and successfully used as a therapeutic agent. 

 The constant current, in restoring the normal condition of 

 nerves, must influence, not only that portion included be- 

 tween the poles of the battery, but the entire nerve ; and 

 the electrotonic condition, with its modifications, explains 

 how this result may be obtained. Undoubtedly the sensory 

 nerves are affected as well as the motor, though we have as 

 yet but little positive information upon this point. A knowl- 

 edge of the fact that the constant current diminishes the ex- 

 citability of the nerve near the anode (anelectrotonos) and 

 increases it near the cathode (catelectrotonos) may become 

 important in determining the direction of the current to be 

 ' employed in different cases of disease. 



In the present condition of the subject of electro-physi- 

 ology, it will be unnecessary to do more than to indicate, as 

 clearly and simply as possible, the laws of the phenomena 

 attending the passage of a constant current through nerves, 

 as far as they have been definitively ascertained. For a most 

 lucid exposition of these laws, the physiological student can- 

 not do better than to consult a lecture recently published by 

 Dr. Rutherford, of Edinburgh. 3 



1 PFLUGER, Untersuchungen uber die Physiologic des Electrotomis, Berlin, 1859, 

 8. 277, et seq. 



* Op. cit., S. 186, et seq. 



8 RUTHERFORD, Eledrotonus. Journal of Anatomy and Physiology, Cambridge 

 and London, 1868, vol. ii., p. 87, et seq. 



