galvanism

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Frog legs experiment from Galvanis De viribus electricitatis in motu musculari

Galvanism is a historical term for muscle contractions caused by electric current. The phenomenon discovered by Luigi Galvani led to the development of modern electrophysiology . At the end of the 18th century, galvanism was considered a fundamental biological discipline; in natural philosophy , electricity was often viewed as a central characteristic of life .

Galvanis concept of animal electricity

Giovanni Aldini's " Ox Battery "

On November 6, 1780, the Italian doctor and anatomist Luigi Galvani accidentally discovered the contraction of prepared frogs' legs under the influence of static electricity. This discovery sparked an intense debate in the decades to come. Alessandro Volta named this branch of research "galvanism" after Galvani. Galvani himself referred to the phenomenon as something called "animal electricity" and believed that he had discovered a distinct form of electricity. So he assumed that the metal released specific animal energy present in the tissue. Volta, on the other hand, claimed that the movements were caused by contact with metals rather than by electricity inherent in the thigh. There is only one form of electricity and the metal electrifies the frogs' legs. Even if Volta's explanation was later confirmed, the idea of ​​animal electricity remained popular for decades and was intensely defended by Galvani's nephew Giovanni Aldini .

Galvanic research was made possible by the Leyden bottle invented in 1745 or 1746 , the first design of a capacitor . In animal experiments , the bottle and a brass wire were used to make connections between the nerves that caused muscle contractions. Almost at the same time, Ewald Georg von Kleist and Pieter van Musschenbroek developed variants of the Leyden bottle, which has a very simple structure: a bottle that is often filled with liquid and encased in metal serves as an energy store and can be connected to an electric machine, for example. The discharge of the bottle can cause electric surges and also experimental irritation of prepared muscles.

Electrical organs

Voltaic column, drawing from Adolphe Ganot Elementary Treatise on Physics: Experimental and Applied 1893
Contemporary caricature of a galvanized corpse

The galvanic experiments also led to greater attention to known facts, such as the ability of some fish to discharge themselves electrically ( electroplaxes ). Best known in this context is Alexander von Humboldt's research into electric eels during his trip to America. In his travel reports, Humboldt writes: "The blackish and yellow-colored water snakes like eels swim to the surface of the water and huddle under the belly of horses and mules [...] Dazed by the noise, they defend themselves with repeated blows of their electric batteries [..] .] I do not remember ever having suffered such a terrible shock from the discharge of a large Leidner bottle as when I carelessly placed both feet on a Gymnotus which had just been pulled out of the water. I felt severe pain in my knees and almost all joints all day. "

Already in 1773 had John Walsh investigations on eels and torpedo made and had come to the conclusion that such fish electricity not only save, but produce itself. Findings about the abilities of fish were Galvani as essential evidence for the existence of a specific animal electricity. On the other hand, in the Transactions of the Royal Society from 1800 , Volta describes the similarity between the Voltaic column he developed and the "natural electrical organ of the electric ray and electric eel". The voltaic column not only increasingly replaced the Leyden bottle in experimental practice, it was also presented by Volta as an argument against independent animal electricity. Here is also Johann Wilhelm Ritter to name, who was active from the late 18th century with basic experiments and discoveries in this area. His "knight column" is the invention of the battery, with which he experimented excessively; not least on his own body and at the expense of his life.

Regardless of the question of animal electricity in its own right, the electrical irritability of muscles and the electrical abilities of some fish raised the question of the importance of electricity to organisms. Many biologists and natural philosophers of the late 18th and early 19th centuries viewed electricity as a central characteristic that distinguishes living beings from inanimate matter.

Research on Executed People

According to the biology historian Michael Hagner , the boom in galvanic experiments was significantly influenced by the establishment of the guillotine during the French Revolution . The guillotine sparked a debate because it was unclear whether the severed head was still capable of consciousness and pain. Joseph-Ignace Guillotin had declared: "With my invention I will cut your head off in an instant without your suffering." Galvanic research not only seemed to allow experimental access to the subject, but also cast doubt on Guillotin's assertion .

In a report on the investigation of those executed from Mainz in 1803, for example, it says: “The halves of the brain [were] removed up to the largest circumference of the marrow. The negative chain was placed on one side of the brain, the positive on the other, and the large bottle discharged. At the first blows, there were strong movements in the muscles of the nose, mouth and cheeks. On the following blows one saw movements in the muscles of the whole face several times. "

Such observations not only raised natural-philosophical and biological questions, they were also discussed controversially in public. In 1803, galvanic experiments were carried out on those executed at the instigation of Friedrich Wilhelm III. largely banned in Prussia. Doctors also used galvanism to determine death by electrical means. In 1819 Mary Shelley published her novel Frankenstein , which is about the creation of an artificial human . In the preface to the third edition of Frankenstein it says: “Perhaps one could revive a corpse, there are examples of this from galvanic experiments; perhaps the matching individual parts of a living being could be put together and given the warmth of life. "

Eventually, there were increasing moral concerns about this galvanic research. Christoph Wilhelm Hufeland explained that the irritation of a decapitated head presumably leads to sensations, awareness and pain. It is immoral and illegal to torture a person in such a way after death. Such views led to increasing criticism of the practice of guillotining that a "humane execution" requires rapid destruction of the brain, since this is the only way to avoid long-lasting pain.

Interpretation of natural philosophy

A central question in natural philosophy of the 18th and 19th centuries concerned the nature of life. While mechanicistic theories were of the opinion that the function of biological organisms resulted from general physical laws, vitalists postulated a life force , often thought of as immaterial , which should separate living beings from inorganic matter.

In early romantic natural philosophy, the galvanic experiments led to electricity being postulated as a life force. Although such an approach was far removed from a classical mechanism because of its romantic design, it was at the same time fixed on an organic materialism that no longer fundamentally differentiated life and spirit from material processes. Johann Jacob Wagner (1775–1841) explained, for example , that “every thought appears as a galvanic process, and thus in principle can no longer be distinguished from the material.” The early romantic idea of ​​an organic unity of nature, body and mind with simultaneous demarcation from Mechanicism is described by Dietrich von Engelhart as "the spiritualization of nature and the naturalization of man".

In romantic natural philosophy, however, this approach could not prevail and at the beginning of the 19th century, Philipp Franz Walther and Joseph Görres once again postulated the primacy of an immaterial soul over matter. Nevertheless, electrophysiology played a decisive role in the demise of classical vitalism in the mid-19th century. While Johannes Müller was still a proponent of the classic life force hypothesis, his students Emil Heinrich Du Bois-Reymond , Hermann Helmholtz and Carl Ludwig rejected vitalism in principle. There were various reasons for the disappearance of traditional vitalism, including the first synthesis of an organic substance ( urea ) by Friedrich Wöhler , Helmholtz's formulation of the law of conservation of energy , the theory of evolution and the new results of electrophysiology.

However, the rejection of vitalism did not generally lead to a reductionism that called for the mind to be returned to the body. In particular, du Bois-Reymond turned with his Ignoramus et ignorabimus against corresponding attempts that were carried out in the materialism dispute by Carl Vogt , Ludwig Büchner and Jakob Moleschott . The new knowledge of biology in general and of electrophysiology in particular led to the bitter world puzzle dispute about the limits of scientific explicability in the late 19th century .

Development of electrophysiology

Representation of the motor centers in the dog's brain, individual regions marked by Hitzig and Fritsch

There was a revival of galvanic thoughts in the middle of the 19th century through the beginning, experimental electrophysiology. Du Bois-Reymond explained: "If I am not mistaken, I have succeeded in awakening the hundred-year dream of physicists and physiologists of the unity of the nervous system and electricity, albeit in a somewhat modified form, into a life-filled reality." Through improved methods of stimulation and new measuring instruments, du Bois-Reymond succeeded in detecting electrical current fluctuations during muscle contraction.

Electrophysiological research was given a further boost by Eduard Hitzig and Gustav Fritsch's description of the electrical excitability of the cerebrum . For a long time, the brain was not considered to be irritable. Humboldt, for example, was disappointed to find that irritation of the brain did not lead to any measurable effects. In 1870, however, Hitzig and Fritsch described that “when certain galvanic currents are passed through the back of the head, movements of the eyes can easily be obtained which, by their nature, can only be triggered by direct stimulation of the cerebral centers.” Using vivisection , Hitzig and Fritsch researched the dog's motor centers. They opened the skull and irritated parts of the cerebrum. It was found that the stimulation of certain regions caused the movement of different extremities and a small spatial shift in the stimulus resulted in a change in movement.

On the basis of these observations, Hitzig and Fritsch developed a representation of the motor centers in the brain for the first time (see illustration). As a result, galvanism not only enabled the development of electrophysiology, but also led to modern localization research in neuroscience .

literature

  • John Heilbron : "The Contributions of Bologna to Galvanism", in: Historical studies in the physical and biological sciences , 1991
  • Michael Hagner : Homo cerebralis. The change from soul organ to brain island, Frankfurt 2000 ISBN 3458343644
  • Erhard Oeser : History of brain research , WBG, Darmstadt, 2002, ISBN 3534149823 .
  • Marcello Pera: La Rana ambigua. La controversia sull'eletricità tra Galvana e Volta , Turin, Einaudi, 1986, ISBN 9788806593100
  • Charlotte Sleigh: "Life, death and galvanism", in: Studies in History and Philosophy of Biological and Biomedical Sciences , 1998
  • Friedrich Steinle: Explorative Experiments Ampere, Faraday and the Origins of Electrodynamics , Franz Steiner Verlag, 2005, ISBN 3515081852
  • Manfred Wenzel: Galvanism. In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 455 f.

Web links

Commons : Galvanism  - collection of images, videos and audio files

Individual evidence

  1. ↑ A comprehensive presentation is offered by: Marcello Pera: La Rana ambigua. La controversia sull'eletricità tra Galvana e Volta , Turin, Einaudi, 1986, ISBN 9788806593100
  2. ↑ Erhard Oeser: History of the brain research , WBG, Darmstadt, 2002 ISBN 3534149823 , p. 91.
  3. ↑ C. Dorsman and CA Crommelin: "The invention of the Leyden jar", in: Janus , 46, 1957
  4. ↑ A detailed discussion of the topic can be found in: Carl Sachs: Investigations on the Zitteraal Gymnotus electricus , Leipzig, 1881
  5. ↑ Alexander von Humboldt: Voyage aux régions équinoxiales du Nouveau Continent: fait en 1799, 1800, 1801, 1803 et 1804. German translation authorized by Humboldt by Hermann Hauff: Journey to the equinoctial regions of the new continent. , Stuttgart, Cotta, 1859.
  6. ^ John Walsh: "On the electric property of the torpedo", Letter to Benjamin Franklin , 1773
  7. ↑ Alessandro Volta: Transactions of the Royal Society , 1800, pp. 403ff.
  8. ^ The experimental program by Johann Wilhelm Ritter. Ernst Haeckel House of Friedrich Schiller University Jena, archived from the original on July 31, 2012 ; Retrieved January 20, 2011 .
  9. ^ Jürgen Daiber: The electrified physicist . Time online. Retrieved January 20, 2011.
  10. ↑ Michael Hagner: Homo cerebralis. The change from the soul organ to the brain . Insel, Frankfurt 2000 ISBN 3458343644 , p. 186.
  11. ↑ Quoted from Rudolf Quanter: The physical and life punishments for all peoples and at all times , Dresden, HR Dohrn, 1900, p. 226.
  12. ↑ Anonymous: “Galvanic and electrical experiments on human and animal bodies. Employed by the medical private company in Mainz ”, Frankfurt am Main, Andreean Buchhandlung, 1804, pp. 45f. ( Digitized version )
  13. ↑ Christian August Struve: Galvanism, a reliable means of testing real death, and means of rescue in apparent death. In: Reichsanzeiger No. II, 1804, Sp. 3675–3678.
  14. ^ Mary Shelley: Frankenstein or Frankenstein or The Modern Prometheus , reprint Frankfurt am Main, Insel, 1988, ISBN 3458327304
  15. ↑ Christoph Wilhelm Hufeland: "Two cabniets letters from Sr. Majesty of the King of Prussia regarding the experiments made on the beheaded and yet to be made", in: Journal der practical Arzneykunde und Wundarztneykunst. Volume 17.3, p. 26.
  16. ↑ Carl Fridrich Clossius : About the beheading , Tübingen, Army Brandt, 1797, p. 28
  17. ^ Johann Jacob Wagner: From the nature of things , Leipzig, Breitkopf and Härtel, 1803, p. 499.
  18. ↑ Dietrich von Engelhart: "Natural philosophy in the judgment of the" Heidelberger Jahrbücher der Literatur "1808 to 1832" in: Heidelberger Jahrbücher , 1975
  19. ^ Gabriel Finkelstein: Emil du Bois-Reymond. Neuroscience, Self, and Society in Nineteenth-century Germany . The MIT Press, Cambridge / London 2013, ISBN 978-0-262-01950-7 , pp. 62-65 .
  20. ↑ cf. for example: Emil Heinrich Du Bois-Reymond: “ On the limits of nature knowledge ”, lecture at the second general meeting of the 45th Assembly of German Natural Scientists and Doctors in Leipzig on August 14, 1872, reprinted in: Speeches by Emil du Bois-Reymond in two volumes , first volume, 1912, pp. 441–473. Leipzig: Veit & Comp.
  21. ^ Frederick Gregory: Scientific Materialism in Nineteenth Century Germany . Reidel, Dordrecht / Boston 1977, ISBN 90-277-0760-X .
  22. ↑ Bayertz, Kurt .: Weltanschauung, philosophy and natural science in the 19th century / 1 The dispute over materialism. Meiner, Hamburg 2007, ISBN 978-3-7873-1777-6 .
  23. ^ Emil Heinrich Du Bois-Reymond: Studies on animal electricity , Volume 1, Berlin, 1848, S.XV
  24. ^ Gabriel Finkelstein: Emil du Bois-Reymond: Neuroscience, Self, and Society in Nineteenth-century Germany . The MIT Press, Cambridge / London 2013, ISBN 978-0-262-01950-7 , pp. 57-114 .
  25. ^ Eduard Hitzig and Gustav Fritsch: About the electrical excitability of the cerebrum , in: Archives for Anatomy, Physiology and Scientific Medicine , 1870, p. 308