Electricity and Galvanism. 127 



most generally diffused means employed by the All-wise Creator for 

 the production of most of the phenomena of the material world. 



If, then, this agent exists so freely diffused in the animal, can 

 we doubt its having some important function to perform? In the 

 torpedo and silurius its influence is obvious, in furnishing them with 

 powerful weapons of defence and attack ; but where its presence is 

 not so evident — where it does not arrest our attention by endowing 

 the animal with a power which enables it to simulate the effects of 

 the lightning flash — can it exist without fulfilling some important 

 purpose ? Natura nihil agat frustra is a universally admitted 

 axiom ; nor must we presume otherwise even when the subject we 

 are investigating appears less endowed with useful applications. 



Prof. Galvani, of Bologna, in 1791, published a Commentary "de 

 Viribus Electricitatis in Motu Musculari," and announced those facts 

 which laid the foundation of that science which bears his name. He 

 then stated that a particular form of electricity, denominated by him 

 animal electricity, existed in animals ; and he believed he merely 

 excited and rendered sensible this electricity by coating a nerve and 

 muscle with metals, but did not regard the latter as the real source 

 of the electricity. 



This celebrated experiment is well known I am sure to all present, 

 but is one of really so marvellous and remarkable a character that, 

 repeat it as often as we may, it can never be looked at without a 

 feeling of wonder and delight. I will take the legs of a frog denuded 

 of their skin, and attached by the lumbar nerves to a portion of the 

 spine. Allowing them to rest on a glass plate, I will place a piece 

 of zinc in contact with the nerves, and allow the feet to rest on a 

 thin slip of silver. They are now at rest, and appear, as they indeed 

 are, dead and powerless. But there exists a power I can call into 

 action which will endow these dead limbs with an apparent life. The 

 only spell required to evoke this power is this piece of wire, with one 

 end of which I will touch the zinc, and with the other the silver. 

 Instantly the legs violently contract, and kick away the silver plate. 



It has been lately stated by Prof. Matteucci, that this curious 

 observation was not original with Galvani, but was made some time 

 before by the celebrated Swammerdam ; and the experiment was ex- 

 hibited by him in the presence of the Grand Duke of Tuscany. 



