An account of the dissection of a Gymnotus electricus : together with reasons for believing that it derives its electricity from the brain and spinal cord, and that the nervous and electrical forces are identical / by Henry Letheby.

  • Henry Letheby
Date:
[1842]
Catalogue details

Licence: Public Domain Mark

Credit: An account of the dissection of a Gymnotus electricus : together with reasons for believing that it derives its electricity from the brain and spinal cord, and that the nervous and electrical forces are identical / by Henry Letheby. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    D, vision U.-The Electrical Properties of the Gyrnnotus. of Hi”06 ,°CCl,py but llttle tlme In tlle consideration of this pari electrh ^ J6CfV f6 3nalogy of the Phenomena of the Gyrnnotus electricus with those of electricity, gave origin to it Y c na™this analogy was farther bo™ out bfth el Clu of Williamson,* Huraboldt/f and others; while moreTecentl ie identity of these phenomena with those of ordinary elcc- £ic.ty has been completely established by the investigations of of. Faradayt on the Gyrnnotus formerly belonging to the proprietom of the Adelaide Gallery; during these, VobLri e shock, deflected the galvanometer, made magnets and effected chemical decomposition. The spark, and evidence of heating effect, were obtained by Mr. Gassiot.§ Faraday found that the laws which regulate the discharge are that the anterior paits of the animal are positive to the posterior; the current is from the head through the water to the tail; and the discharges are voluntary. He endeavoured to form some estimate of the quantity and force of the electricity sent by the fish, by a comparison with that of a charged Leyden jar; and he thinks from the sensation, the degree of deflection, and amount of chemical decomposition, that a medium discharge of the fish was at least equal to the electricity of a Leyden battery of fifteen jars, containing 3,500 square inches, coated on both sides and charged to the highest degree. The phenomena of other electrical fish, I make no doubt, are also due to a similar force. I am not aware, however, that any experiments to prove this have been made upon the Silurus, Rhi nobat us. Trichi urus, or Tetrodon electricus: but that the force' in the Torpedo is electrical, is as sufficiently proved as that of the Gyrnnotus has been; indeed from its being better known and easier of access, it was the first in which the identity was established. As early as 1712, Kcempfer|| compared its shock to lightning: sixty years afterwards Walsh^f recognized the different electrical conditions of the back and belly, and was, in consequence, able to * Pliil. Transactions, 1775, p. 94. t Recueil ^Observations de Zoologie, &c., tom. i. p. 49. t Phil. Transactions, 1G39, p. 1. $ Trans. Elec. Soc. 1839, pages 175, 179. || Amani. Exot. 1712, p. 514. II Phil, Transactions, 1773.
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