318 PRESENT STATE OF OEGANIC ELECTRICITY. 



We are not, indeed, acquainted with tlie actual chemical or 

 physical causes of electrical excitement in any animal texture 

 or organ ; but we now know the direction and relations of the 

 current in and to the anatomical structure in certain cases. 

 This is a secure step in the proper direction, and one which 

 has yet to be taken in vegetable electricity. 



At present, therefore, it can only be stated generally tliat 

 the disturbance of electric equilibrium in the textures and 

 organs of the plant is due to the chemical action which plays 

 so important a part in the organic processes — at its surface, as 

 during transpiration, respiration proper, and the fixation of 

 carbon — and in its interior, durmg the reaction of its ascend- 

 ing and descending sap, with the substances contained in the 

 cells of its various structures. In the same manner, no precise 

 statement can be made at present regarding the arrangements 

 by means of which electrical currents are produced in the 

 plant. The researches of Becquerel* have proved that a 

 current is produced when two liquids of acid and alkaline re- 

 actions respectively, and separated from one another by a 

 porous substance, are connected either by a fluid or solid con- 

 ductor. It is quite evident that similar physical and chemical 

 conditions for the production of currents exist in innumerable 

 forms in the organisation of vegetables. It is, however, im- 

 possible in the present phase of the subject to define them 

 with greater precision. 



Animal Electricity. 

 The first discovery in animal electricity was the deter- 

 mination of the electrical character of the shock of the 

 Torpedo by Walsh in 1772. The development of the sub- 

 ject has since been retarded, not only by its own intriQsic 

 difficulty, but also by the greater attractions of those depart- 

 ments of general electricity which were opened up by 



* " Recherclies sur les circuits electro-cliiinic[ue simple forme de liquides." 

 — Compies Eeiidus, torn. xxiv. 



