398 BIOLOGY. [BOOK vi. 



We cannot pass over in absolute silence the electric properties 

 of the nerves ; but we shall speak of them briefly. It seems to 

 us that, in physiology, far too much importance has been 

 attached to this secondary question. People have allowed 

 themselves to be drawn too far by the idea and desire of 

 establishing a connection between the electric agent and the 

 nervous agent. But all identification between these two forces, 

 or rather these two modes of molecular vibration, is manifestly 

 erroneous. It is true that the electric currents bring nervous 

 motricity into play with great energy, but many other 

 mechanical, physical, and nervous excitants do as much. 



As to the electric current which, as M. Dubois-Eeymond has 

 shown, is established between two electrodes placed, one on the 

 external surface of a nerve, the other on its sectionised surface, 

 it is not peculiar to the nervous tissue, and always establishes 

 itself from the external surface to the section; it is simply 

 the result of nutritive chemical actions. Also, it appears indif- 

 ferently and in the same manner, whether the nervous fibre is 

 motory or sensitive. A nerve which has just been crushed with 

 blows of a hammer, and has lost its motricity, nevertheless 

 engenders an electric current ; for, in spite of the violence of the 

 lesion, which haa destroyed the form of the nervous fibres, their 

 substance still lives some time, or at least certain parts of this 

 substance ; for example, the nervous sheaths and the neurolemma. 



Nevertheless a nervous current is established throughout the 

 length of the nerve, and is perceptible in the galvanometer, 

 when we have excited by a continuous current a portion only of 

 this nerve, not comprehended in the circuit of the galvanometer. 

 This is what M. Dubois-Reymond has too pompously named the 

 electro-tonic force of the nerves. Is this faculty of electric 

 irradiation peculiar to the nervous fibres, as M. Dubois-Eeymond 

 would assert ? It does not seem that this so-called special 

 property has been sufficiently sought for in the other fibrous 

 tissues, and Matteucci has demonstrated it, though with more 

 difficulty, in a piece of cotton soaked in a conductor liquid. 



