32

Bioelectromagnetism

Edward Bancrof (1744–1820), an American scientist and politician, had lived in Guiana for some

years before coming to England, and in 1769 showed that the shock from a torpedo, gymnotus electricus,

is electrical in nature and the characteristics of the electric discharge of the torpedo are similar to those

from a battery of a Leyden jar. Te similarity between the electric discharge of the electric fsh and the

shock by the Leyden jar was found. Tis similarity led to the use of the Leyden jar in electrotherapy. Te

Leyden jar made it possible to demonstrate the electric stimulation of nerves and muscles, which is the

reason for its therapeutic application instead of electric fsh.

During the second half of the eighteenth century, the law of electrostatic force was formulated. Joseph

Priestley (1733–1804), a chemist and English Presbyterian, formulated the inverse-square law of electri­

cal attraction and repulsion in 1767, then Henry Cavendish (1731–1810), a British chemist and physicist,

experimentally demonstrated it in 1772, and fnally Charles Augustin de Coulomb (1736–1806), a French

physicist, completed the electrostatic force law in 1785.

2.3.2 Development of Bioelectricity

2.3.2.1 Early Stage

Trough the 1780s and 1790s, Luigi Aloisio Galvani (1737–1798), an Italian anatomist and physicist,

professor of Anatomy at the University of Bologna, Italy, discovered bioelectricity-animal electricity.

With assistance of his wife, Lucia Galeazzi (1743–1788), and his two nephews, Camillo Galvani (1753–

1828) and Giovanni Aldini (1762–1834) who later became professor of Experimental Physics at Bologna,

Galvani performed famous experiments in neuromuscular stimulation. He published its results in Latin

in 1791, which led him to be the founder of electrophysiology. Te publication was divided into four

parts. Tis work has been translated into many languages. In case of English, the translated title was

Commentary on the efect of electricity on muscular motion (Green, 1953). According to this publication,

in the frst part, he investigated the efects of artifcial electricity on the nerves and muscles of frogs. On

January 26, 1781, a dissected and prepared frog by Galvani was placed on a table on which was an electric

machine, but at some distance from it and not connected with it in any way. Violent muscular contrac­

tion occurred when an assistant happened to touch the femoral nerve with a scalpel. Galvani began

immediately to investigate this unexpected phenomenon (Rowbottom and Susskind, 1984).

Te most-cited second part of his publication is the results of the investigation under the title of

Te efects of atmospheric electricity on muscular motion. Tis part is only short. Galvani attached the

nerve of the frog leg to the side of the house, and grounded nerves in an adjacent well. Contractions

were obtained when every fash of lightning occurred. By August and September of 1786, he was try­

ing to obtain contractions from changes in atmospheric electricity during ordinary calm weather in

open space. He suspended frog preparations from an iron railing in his garden by brass hooks inserted

through the spinal cord. He happened to press the hook against the railing when the leg was also in

contact with the iron railing. He found that there were contractions of the muscles. His thought was that

the contractions were due to the slow accumulation of atmospheric electricity within animal, which was

suddenly discharged when the hook was pressed against the iron railing. Observing frequent contrac­

tions, he repeated the experiments in a closed room (Rowbottom and Susskind, 1984).

Te third part of his publication came to new discovery under the title of Te efects of animal electric­

ity on muscular motion. Te earliest results are related below:

But when I had transported the animal into a closed chamber and placed him on an iron surface,

and had begun to press against it the hook fxed in his spinal cord, behold the same contractions

and the same motions! Likewise continuously, I tried using other metals, in other places, other

hours and days; and the same result; except that the contractions were diferent in accordance with

the diversity of metals, namely more violent in some, and more sluggish in others. Ten it continu­

ally occurred to me to employ for the same experiment other bodies, but those which transmit

little or no electricity, glass for example, gum, resin, stone, wood, and those which are dry; nothing