128 Traces of Unity in 



'the same way, near to the crural nerves. When the frog 

 possessed a great deal of vitality, the crural nerves 

 gradually approached my hand, and strong contractions 

 took place at the moment of contact.' And again : 

 ' Being desirous to render this phenomenon more 

 evident, I formed the arc by applying one of my hands 

 to the spinal marrow of a warm-blooded animal, while 

 I held the frog in such a manner that its crural nerves 

 were brought very near to the abdominal muscle. By 

 this arrangement the attraction of the nerves of the frog 

 became very evident.' 



About this time, however, the discovery of the 

 voltaic battery had given the victory to the opinions 

 of Volta a victory so complete that nothing more 

 was heard about animal electricity for the next thirty 

 years. 



In 1827, Nobili* brought back the subject of animal 

 electricity to the thoughts of physiologists by discover- 

 ing an electric current in the frog. He made this dis- 

 covery by means of the very sensitive galvanometer 

 which he himself had invented a short time previously 

 an instrument which, as perfected by Professor Du 

 Bois-Reymond and others, by Sir William Thomson 

 more especially, ought to be as prominent an object as 

 the microscope in the laboratory of every physiologist. 

 Immersing each end of the coil of the instrument in a 

 vessel containing either simple water or brine, and com- 

 pleting the circuit between the two vessels with a gal- 

 vanoscopic frog the fragment of the spine being im- 

 mersed in one vessel, and the paws in the other he 

 found that there was a current in the frog from the feet 

 upwards, which current would cause a considerable per- 

 manent deflection of the needle to 30 or more, if brine 



* "Bibl. Univ.," 1828, T. xxxvii, p. IO. 



