392 ANIMAL ELECTRICITY. 



power which, although constantly employed., has the 

 capability of continually renewing itself by some inex- 

 plicable connection existing between it and many 

 external influences. We know that certain conditions 

 are necessary to the health of animals. Diseased diges- 

 tion, or any interruption in the circulation of the blood, 

 destroys the vital force,, and death ensues. The pro- 

 cesses of digestion and of the circulation are perfectly 

 understood, yet we are no nearer the great secret of the 

 living principle. 



Animals are dependent on several external agents for 

 the support of existence. The oxygen of the air is 

 necessary for respiration. Animal heat, as will be 

 shown presently, is in a great measure dependent upon 

 it. The external heat is so regulated that animal 

 existence is comfortably supported. Electricity is 

 without doubt an essential element in the living pro- 

 cesses; and, indeed, many physiologists have been 

 inclined to refer vital force to the development of elec- 

 tricity by chemical action in the brain. This view has, 

 however, no foundation in experiment beyond that 

 afforded by the appearance of electric currents, when 

 the brain is excited. This proves no more than that 

 the operations of mind develope physical power in the 

 matter with which it is mysteriously connected. 



The phenomena of the Torpedo and Gymnotus we 

 have already noticed,* and there are other creatures 

 which certainly possess the power of secreting and dis- 

 charging electricity. Galvani's experiments, and those 

 of Aldini, appear to show and the more delicate 

 researches of Matteucci have satisfactorily determined 



* ID addition to the memoirs already referred to, Note p. 211, 

 see Carlisle, On the battery of the Torpedo, governed by a voluntary 

 muscle. Phil. Trans., vol. xcv. p. 11. Todd, Experiments on the 

 Torpedo of the Cape of Good Hope. Ibid., vol. cvi. p. 120. Todd, 

 Experiments on the Torpedo Elect ricus at La Rochelle.lbid.., 

 vol. cvii. p. 32. 



