Full text of "Commentary On The Effect Of Electricity On Muscular Motion"
537 Gl8c
55-07177
on the effect of eiectricity on
muscular motion*
Galvani on Electricity
A TRANSLATION
of Luigi Galvani's De Viribus Electridtatis
Elizabeth Licht, Publisher 1953
In Motu Muscuiari Commentarius
Commentary on the
EFFECT OF ELECTRICITY
ON MUSCULAR MOTION
by Robert Montrayille Green, M.D.
Emeritus Professor of Anatomy, Harvard Medical School
Copyright 1953 by
All Rights Reserved
THE TEXT OF THIS PUBLICATION OR ANY PART
THEREOF MAY NOT BE REPRODUCED IN ANY MANNER
WHATSOEVER WITHOUT PERMISSION IN WRITING
FROM THE PUBLISHER
WAVERLY PRESS, INC.
PRINTED IN THE UNITED STATES OF AMERICA
Preface
The name of Galvani has found its way into many languages as
a common word because of a report he wrote on electricity in 1791
in Latin. That remarkable and important work has been translated
into three languages but has never before been published in English.
Most important documents on science were written in Latin up to
the time of the eighteenth century. Until then most scientists could
speak and write the language which was international and the mark
of education. Galvani's commentary on electricity first appeared in
a scientific journal, the seventh volume of the proceedings of the
dated March 27, 1791 (De Bononiensi Scientiarum Et Artium In-
stituto Atque Academia Commentarn y //p/, VII ", 363-418). In the
following year, Galvani's nephew, Giovanni Aldini, reprinted it in
book form along with an introduction to electricity by himself in
Latin, and two letters between Galvani and Carminati in Italian.
Aldini also wrote a dozen footnotes to the original Galvani article.
In order to illustrate his own footnotes, Aldini altered the four
original illustrative plates of Galvani which had 17 figures, with
three plates containing 27 figures. In this, the first complete English
translation of Galvani, we have used the original four plates and
therefor omitted the footnotes of Aldini which do nothing to improve
the eloquently simple Galvani original. We have however included
translations of the rest of the Aldini book published in Modena
in 1792.
We believed that Galvani's contribution to electricity and elec-
trophysiology was of such importance that it should become more
available and available in English. We asked Doctor Robert M.
Green, a scholar and linguist, to translate the original article and the
rest of the Aldini book. To introduce this superior translation we
invited the academic heir of Galvani, Dr. Giulio C. Pupilli, professor
of physiology at the medical school of the University of Bologna
recount the highlights of the life and writings of Galvani.
Additional thanks go to many who loaned encouragement and
assistance: to the Rector of the University of Bologna
'tiano Mazzanachio, and to Dr. Biffi, Executive Secretary of the
VI PREFACE
to the Accademia deWIstituto delle Science di Bologna, for the privi
lege of inspecting the original manuscripts; to Dr. EL Fischgold of
Yale University Library for photographs of the illustrations; to the
Bibliotheque Nationale of Paris
and to the Boston Medical Library for the use of the Aldini edition.
SIDNEY LIGHT, M.D.
Table of Contents
Page
INTRODUCTION GiuKo C. Pupilli ix
DISSERTATION ON THE ORIGIN AND DEVELOPMENT OF THE
THEORY OF ANIMAL ELECTRICITY. Giovanni Aldini I
COMMENTARY ON THE EFFECTS OF ELECTRICITY ON MUSCULAR
MOTION. Luigi Galvani 21
PART 1 24
PART II 36
PART III 40
PART IV 60
LETTER FROM BASSANO CARMINATI 85
LETTER TO BASSANO CARMINATI 8g
Vll
Introduction
The Bologna Institute of Arts and Sciences was founded by Count
Luigi Ferdinando Marsili in 1714 in the Poggi Palace
seat of the University of Bologna
annual publication (Commentaries) in the seventh volume of which
appeared the report which is translated in full for the first time in
the English language in this volume. De viribus electricitatis in motu
musculari Commentarius (Commentary on the forces of electricity in
their relation to muscular motion) was published In De Bononiensi
Scientiarum et Artium Institute atque Academia Commentarii, 1791,
VII, 363-418. The author of this pioneering work in electrophysiol-
ogy was the 54 year old Professor of Obstetrics at the Institute. 1
On the one-hundredth anniversary of his birth, the Academy of
Sciences of the Institute published under one cover all the then
known writings of Galvani 2 in addition to a Rapporto concerning
them by the physicist Silvestro Gherardi. On the two-hundredth
anniversary of his birth all other writings of Galvani discovered
during the preceding century were published. 3 The importance of
De viribus was appreciated in many countries very soon after pub
lication and a half century later, the noted German physiologist du
Bois-Reymond wrote, "The storm which began with the publica
tion of this Commentary in the world of physics, physiology and
1 In Gaivani's time, at Bologna , the University and the Institute of Sciences
institutions. The University was located in the Archiginnasio in Peace Square
Piazza Galvani. The Institute was a sort of a graduate school of sciences and represented the
active core of scientific life in Bologna , well known even abroad (Simeoni, L., Storia del-
PUniversita di Bologna. Vol. II, Bologna Academy of Inquieti
time near 1690, thanks to the efforts of men interested in encouraging experimental trends in
scientific research. The Academy merged with the Institute and took its name. Later on it
was also called benedettina, in honor of Pope Benedict XIV of Bologna
benefactor.
2 Galvani, L. Opere edite ed inedite. Bologna
sut manoscritti del
read before the Academy during the sessions of November 7 and 14, 1839; b) the Elogio del
celebre Professore Luigi Galvani, by Professor Giuseppe Venturoli, read before the Academy
on May 24, 1802,
'Galvani, L. Memorie ed esperimenti inediti. Bologna
first Italian edition of De viribus electricitatis, with the Latin text (by E. Benassi ) ; b) an essay
on Galvani's iconography (by G. Zucchini); c) a description of Luigi Galvani's manuscripts
in possession of the Royal Academy of Sciences of the Institute of Bologna
d) a contribution to the bibliography of Galvani's published works (by L. Barbieri).
IX
X INTRODUCTION
medicine, can only be compared to that which arose on Europe 's
political horizon during the same period in the final years of the
eighteenth century." 4
A year later, a second edition was published at Modena
form, and included a dissertation and notes by Giovanni Aldini
(Galvani's nephew) together with letters from the correspondence
between Galvani and Bassano Carminati, Professor of Medicine at
the University of Pavia
between the schools of Bologna and Pavia
is here presented for the first time in any language other than the
original Latin.
Fulton and Gushing 7 have published a comprehensive bibliog
raphy De viribus electricitatis which lists a German translation pub
lished in 1793 at Prague
version about a century later by Arthur Joachim von Oettingen at
is that of Paul Antonin. 10
Galvani first began his studies on animal electricity in iy8o n but
prudence and thoroughness delayed his decision to publish his find
ings. He was performing experiments on nervous excitability in frogs
(prepared in the manner which physiologists soon came to call the
" Galvani preparation") when he observed that under the influence
of distant electrical discharges, violent muscle contractions are noted
if the lumbar nerves of the animal are touched with metal instru
ments. It should be related, in this connection, that a few years
4 du Bois-Reymond, E. Untersuchungen uber thierische Elektricitat. 1848, 1.
6 Galvani, A. De viribus electricitatis in motu musculari commentarius, cum Joannis Aldini
dissertations et notis. Modena
6 The letter addressed to Carminati by Galvani was first published in the Giornale Fisico-
medico, 1792, II: 131.
7 Fulton, J, F. and Gushing, H. A bibliographical study of the Galvani and the Aldini writings
on animal electricity. Annals of Science, 1936, I: 239.
8 Galvani, A. Abhandlung uber die Krafte der thierischen Elektricitat auf die Bewegung der
Muskeln nebst einigen Schriften der H. H. Valli^ Carminati, und Volta uber eben diesen Gegen-
stand. Translated by D. Johann Mayer, Prague
9 Galvani, A. Abhandlung uber die Krafte der Electricitat bei der Muskelbewegung. Trans
lated by A. J. von Oettingen. Leipzig
10 Sirol, M. Galvani et le Galvanisme. Paris
11 Galvani's use of the electrostatic machine (artificial electricity) in producing muscular
contraction is reported in folders of the Manuscripts. The first experiment (Plic. //, Fasc.
A) is dated November 6, 1780, but this was not the first observation made by Galvani (2).
On the top of the sheet of paper he wrote, "Frog prepared in the usual manner."
before, in Bologna
caria (1758) were able to demonstrate electrical excitability in the
muscles of dead frogs. At that time the reaction was attributed to
the colpo di rltorno^ an explanation advanced by Galvani him
self. Although Galvani was telling his anatomy students 12 that the
nervous fluid was animal electricity, he himself was not satisfied
fully with the explanation which he was offering, and believed that
he had discovered a new phenomenon, which was his greatest con
tribution.
The significance of the experiment of Galvani was emphasized by
Maiorana 13 in his discourse during the Galvani commemoration of
1937. The phenomenon of the colpo di ritorno, which (in Galvani 's
time) could be explained as a simple effect of electrostatic induc
tion, contains the germ of modern wireless telegraphy. "Great things
have small beginnings. What in Galvani's hands could move a mus
cle, brought Marconi's voice across oceans." 14
In the beginning Galvani investigated the effects of artificial elec
tricity on the nerves and muscles of frogs. Later he performed sev
eral experiments on warm-blooded animals with the natural elec
tricity of atmospheric discharges, assisted by his nephew Camillo
Gaivani. He discovered that natural discharges caused lasting mus
cular contractions whether the skies were cloudy or clear, from
which he concluded that his frog preparation was "an electric cur
rent meter through which the electric fluid of nearby bodies passed;
the most delicate electrometer yet discovered." 15 But it was in the
course of studying the effects of electricity in bright daylight that
he made his most valuable discovery. The description of this experi
ment in one of his Manuscripts (Fasc. H del Plic. V} is worthy of
quotation. "Accordingly, on an evening early in September 1786, we
placed some frogs horizontally on a parapet, prepared in the usual
manner by piercing and suspending their spinal cords with iron
hooks. The hooks touched an iron plate; b,ehold! a variety of not
12 See: Alcuni passi estratti dalle Lezioni pubbliche d'Anatomia del eel. Galvani, which ap
peared in Opere edite ed inedite (2).
13 Maiorana, Q. Commemorazione di Luigi Galvani. Celebrazione del secondo Centenario
della nasclta di Luigi Galvam. Fasc. I. Bologna, 1938.
14 This is what was sent in the celebrated communication from the Royal Society of Edin
burgh to the University of Bologna on the 2ooth anniversary of Galvani's birth.
16 This conclusion appears in Fasc . A, of Plic. IV of the Manuscripts following notes
eferring to several experiments.
Xll INTRODUCTION
infrequent spontaneous movements in the frog. If, when they were
quiescent, the hook was pressed with the finger against the iron
surface, the frogs became excited almost as often as this type of
pressure was applied. When this was observed . . ."
At the beginning of the Third Part of the Commentary (the most
important part) it is interesting to note 2 that while the manuscript
said that the hook piercing the spinal cord of the frog was made of
iron (of the same metal as the railing on which the animal was placed),
in the printed copy the small instrument is described as being made
of copper. Galvani noted that the response was more readily ob
tained with a bimetallic arc than when using a single metal. Subse
quently, in the Commentary, he stressed the greater efficacy of
heterogeneous over homogenous arcs, which was the basis of what
later came to be called Galvanism and is today called electro
dynamics.
At first, Galvani believed that metals possessed the property of
electrical discharge. From his Manuscripts it appears that the first
experiment performed with a metallic arc occurred on September 20,
1786. The observations made on that day and during the month
which followed were collected in a folder entitled, Esperimenti circa
Velettricita de' metalli and appeared in print on October joth under
the title of De animali electricitate.
Soon afterwards, Galvani was strongly convinced of the existence
of animal electricity which was discharged by metallic arcs, but he
was a thorough investigator and required proof, "for it is easy in
experimentation to be deceived, and to think one has seen and dis
covered what one has desired to see and discover/ 7 (Commentary,
Part Three). The new observations, made by him on frogs and other
animals, led him to believe that a fluid, similar but not identical
with the electrical fluid, might flow through the arc. He called this
phenomenon electricitatis excursus His theory was finally sum-
10 In the volume DeWuso e delFattivita delfarco conduttore nelle contrazioni del muscoli
(Anonymous, Bologna, 1794) and in the Memorie to Spallanzani (20), the phenomenon was
called torrante ekttrica. Gherardi in his Rapporto on Galvani's Manuscripts (2) as well as in
his speech to the Academy on February 24, 1842 demonstrated that Galvani was the "true
and only author" of Trattato deWarco conduttore and the Supplement. The phenomenon of
muscular contraction elicited without metals is described for the first time on pages 5 and 7
of the Supplemento. In addition it is stated in the Trattato and the Supplcmento that con
tractions may occur even at the moment of circuit interruption. Galvani stated that a "con
stant and continuous current" flows during the entire time the arc is complete.
INTRODUCTION Xlll
marized as follows (Commentary, Part Four), "it would perhaps
not be an inept hypothesis and conjecture, nor altogether deviating
from the truth, which should compare a muscle fiber to a small
Ley den jar, or other similar electric body, charged with two oppo
site kinds of electricity; but should liken the nerve to the conductor,
and therefore compare the whole muscle with the assemblage of
Ley den jars."
The publication of the Commentary, written in Galvani's lucid
and highly expressive prose aroused great interest among scientists
in Italy and elsewhere. Every experiment described was repeated
to check for accuracy and to determine the meaning of this extra
ordinary phenomenon. Alessandro Volta, already famous for his
important discoveries in electricity, at first seemed to agree with
Galvani's explanation of animal electricity; but this acceptance
lasted only a few months, for when the idea of contact electricity
occurred to him he expressed doubts about Galvani's hypothesis,
and embarked on further research which led to the production of
electric current from a pile of heterogeneous metals.
The long debate which stemmed from this divergence of opinions,
kept alive by ingenious experiments by both Galvani and Volta,
represents one of the most memorable and fruitful arguments in
the history of science. It reflects the ardent passion which was the
glory as well as the torment of these two great spirits. According to
Volta, the possibility of exciting muscular contractions with mono
metallic arcs depended only on the heterogeneity of the substances
presented by the contact points of the arc with the muscle through
which electricity was generated. To the objections of Volta, Galvani
responded with the results of his experiments which in effect marked
the beginning of electrophysiology. The first experiment publicly
made in 1794 was virtually the discovery of the polarization poten
tial of muscle. When in a nerve-muscle frog preparation the free
end of the nerve is laid across the muscle, contraction is seen at the
moment of contact. The second experiment, announced in 1797,
demonstrated the existence of injury potential in nerves. When two
isolated frog legs are placed in contact, if the sectioned surface of
the nerve of each is placed on the intact surface of the other, the
muscles of each contract when the circuit is closed (that is, when a
second contact is established). This experiment conducted without
XIV INTRODUCTION"
any metal proved that living tissue is generally the seat of electrical
currents.
In order to collect new data to support his theory, Galvani in
vestigated the electrical properties of marine torpedoes. Although
he was not in good health, Galvani embarked on a tiring sea voyage
in May 1795, to Senigallia and Rimini, whence he returned with
notes on his daily observations. The pages of this Taccuino (Pocket
Note-book) reflect the passionate zeal of this great- biologist, for
they are lively vignettes which arouse admiration and deep affection.
This valuable autograph was printed for the first time in i869. 17
In 1912 the original was purchased by the City of Bologna for the
Library of the Archiginnasio and was reproduced in facsimile in
1937. 18 A report of his trip to and studies along the Adriatic coast
was made by Galvani before the Academy of Sciences of the Istituto
on February n, 17 96 as reported in the Memoria V Sulla elettricith
animale, addressed to Lazzaro Spallanzani. 20 After differentiating a
vigorous autochthonous true electric current in torpedoes, Galvani
tried to find out "whether it was the same current as produced in
the laboratory, and whether the same conductors could be used for
each type." He discovered that "the (electrical) fluid in the nerves
of the organs was identical with that of the muscles," and con
firmed Girardi's observation 21 that the same nerves supply the dor
sal muscles mentioned, with similar " substance, structure and
texture."
After Galvani demonstrated that muscular contractions were
noted in frogs without the use of metals, Volta postulated that elec
trical flow was not peculiar to metals alone but also to second class
conductors. It was this research of Galvani which brought Volta to
17 Taccuino delle esperienze del Gahani sulla Torpedine fatte a Senigaglia ed a Rimini Panno
1795. Memorie delPAccademia delle Scienze dell'Istituto di Bologna, 1869, Series II, 9, 177.
It is part of the report Di due preziosi mss. del Gahani sulla, Torpedine, which Gherardi read
on May 7, 1868.
18 // Taccuino di Luigi Gahani. Bologna, 1937.
19 Dissertazione accademica del Gahani sulla Torpedine. Memorie delPAccademia delle
Scienze delPIstituto di Bologna, 1869, Series II, 9, 163, It was reported together with Tac~
cuinoj in the Gherardi report (17).
20 Memorie sulla elettricita animale di Luigi Galvani P. Prof, di Notomia nella University
di Bologna al celebre Abate Lazzaro Spallanzani Pubbltco Professore nella University di Pavia.
dggiunte alcune elettriche esperienze di Gio. Aldini P. Prof, di Fisica. Bologna, 1797.
21 Girardi, M. Saggio di osservazioni anatomiche intorno agli organi elettrid del/a Torpedine.
Memorie di Matematica e Fisica della Societa italiana, 1768, III: 553.
INTRODUCTION XV
the invention of the voltaic pile, following which galvanism achieved
its great and unexpected usefulness. 22 From a review of the docu
ments of this titanic contest which attracted the attention of the
whole of scientific Europe, we can appreciate that their opposing
views faithfully represent the true aspect of the facts.
Galvani's merits as a physicist and physiologist obscured his con
tributions to anatomy, yet his morphological investigations by them
selves would have been sufficient to secure his reputation. His first
publication 23 dated 1762, discussed the anatomy and pathology of
bones. These Theses, according to the custom of the times, were
publicly discussed by Galvani at the Archiginnasio (to enable him
to lecture at the University). His first dissertation inserted in the
Commentaries of the Academy is dated 1767 and was concerned
with bird kidneys. 24 In order to investigate the disposition and thin
structure of renal tubules, Galvani caused a natural injection of
the tubules by ligating the ureters and in that way anticipated by
almost a century, the approach of Hoppe-Seyler and Zaleski. In
that paper, for the first time, the three layers of the ureteral walls
as well as the peristaltic and antiperistaltic motions of the ureters
were described.
In his second dissertation, 25 read before the Academy on February
19, 1767, Galvani reported the results of his experiments on the
nasal mucosa in men and several animals, and described in detail
the mucous glands and the tubercles situated in the inferior portion
of the septum and the anterior portion of the inferior turbinates.
He also read several Latin essays 26 before the Academy on the struc
ture and functions of the ear in birds shortly before Scarpa published
his famous paper on the round window and secondary tympanum. 2 !
22 The relationship between Galvani's discoveries and the subsequent evolution of science
is well illustrated by Maiorana (13).
^Galvani, A. De ossibus. These physico-medico-chirugicae (sic). Bologna, 1762.
24 Galvani, A. De renibus atque ureteribus volatitium* De Bononiensi Scientiarum et Artium
Institute atque Academia Commentarii, 1767, V: 500.
25 Galvani, A. Disquisitiones anatomicae circa membranam pituitariam. This appears in
Opere edite ed inedite (2).
28 The first dissertation on this subject was read on May 5, 1768; the sixth and last was
read on April 25, 1776. Neither of these dissertations could be found in the Archives of the
Academy (3).
27 Scarpa, A. De structura fenestrae rotundae auris et de tympana secundario anatomicae
observationes . Modena, 1772.
XVI INTRODUCTION
In this paper published at Modena in 1772, the author credited
himself with many of the facts communicated by Galvani between
1768 and I77
complete work on this subject, delaying for a future date the pub
lication of observations overlooked by Scarpa, 29 in the Commen
taries of the Academy.
Several historians and anatomists have commented on the great
value of Galvani's investigations on the ear. 30 He discussed the vari
ation in diameter of the auditory canal, its straight direction, slight
depth and different configurations in various kinds of birds. The
middle ear canal is treated only sketchily by Scarpa but described
in detail by Galvani who compares it to the aqueduct of Falloppia
in man and mentions his discovery of a small nerve branch and
artery within it. He was the first to write of the bony cavity leading
to the oval or round window, which he called the antevestibolo . He
investigated the function of the two muscles which end and are
inserted into the auditory ossicle. He also followed the entire course
of the chorda tympani by means of a lens. He noted that the cavity
of the labyrinth was lined with a dense lucid membrane. In the
canal, replacing the cochlea, the presence of a double dividing lamina
with a cartilaginous aspect was demonstrated through which a
branch of the acoustic nerve travels as far as the apex. He also
noted the great size of the semicircular canals and their colliculi
nervei. Galvani was also the first to discover that the labyrinth is
provided with an artery which enters that cavity by an opening
situated at the origin of the larger semicircular canal where it di
vides into several capillaries.
28 According to many biographers of Galvani and Scarpa, a dispute over the priority of
observations on the ear was aroused among the schools of Bologna, Modena, Padua and
Pavia. According to Scarpa these observations were made by some of his masters and by
many of Morgagni's pupils. According to Galvani, lecturers of the Studio of Bologna and
professors of Parma were the first to make these observations. This dispute was probably
less serious than the published reports would indicate. (Favaro, G. Antonio Scarpa e I 1 Urn-
versita di Modena. Modena, 1932), When Scarpa was a student he spent his summers in
Bologna to obtain practice in surgery. (Favaro, G. Antonio Scarpa e FUniversita di Padova.
Atti R. 1st. ven Sci., Lett. Arti, 1931-1932, II.) . This was during the very years in which
Galvani was working on the ear. There is probably some connection between these facts.
29 Galvani, A. De volatilium aure, De Bononiensi Scientiarum et Artium Instituto atque
Academia Commentarii, 1783, VI: 420.
30 Medici, M. Elogio di Luigi Galvani. Bologna, 1845; Bilancioni, G. Galvani anatomico
ddForecchio. II Vaisalva, 1934, X: 545; Castaldi, L. Nel bicentario della nascita di Luigi Gal
vani. Riforma med., 1937, LIII: 937.
INTRODUCTION XV11
He called attention to the incantesimo of the heart, a momentary
cessation of heart pulsations which he noted in frogs when a needle
was inserted into their spinal canals. 31 He saw for the first time,
the phenomenon of inhibition, the theory of which later became so
important in physiology and psychology.
All of Galvani's writings show exhaustive thoroughness, masterly
observation and literary excellence. He was also an eloquent speaker
and called upon to deliver speeches during academic ceremonies 32
especially as exemplified in the excellent De manzoliniana supel-
lectili oratio given in 1777 at the dedication of the Anatomical
Theatre. 34
Luigi Galvani was born on September 9, 1737, in a house which
may still be seen on Via Marconi, 25, in the center of Bologna, into
a family which had produced several illustrious men. Upon the
completion of his collegiate studies he attended medical classes with
some famous teachers of his time: Jacopo Bartolomeo Beccari and
Domenico Maria Gusmano Galeazzi. He obtained his degree in
medicine and philosophy on July 15, 1759^ anc * on May 13, 1761
31 A few scattered sheets, newly discovered, were added by Gherardi (2) to Plic. // of
Galvani's Manuscripts. One of these is dated 1778 and records the effect of spinal puncture.
32 Ten Latin orations delivered during graduation ceremonies from 1790 to 1797 are in
cluded in the Pile. XII of Galvani's Manuscripts (2). When Galvani's nephew Giovanni
Aldini received his degree on November 25, 1782, Galvani delivered an eloquent oration.
More than a century later this speech was published by a descendant of Galvani (Galvani, L.
Orazione per la laurea di G. Aldini. Translated into Italian by Augusto Chiesa. Bologna,
1888).
38 Galvani, A. De manzoliniana supellectili oratio. Bologna, 1777. Anna Morandi was born
in Bologna in 1716, married Manzolini and died in 1774. A learned anatomist, she held a
chair at the University and became best known for her ability to make wax anatomical figures.
The Stanza (also called Camera or Gabinetto) of Anatomy at the Institute later received these
figures.
34 Minor writings of Galvani include: a) De aeriformibus principiis Thermarum porrec-
tanarum dissertatio, read before the Academy on November 5, 1789, and published by Michele
Medici in "Memorie delFAccademia delle Scienze dell'Istituto di Bologna, 1851, III: 61;
b) Sentimento del Dottore Luigi Galvani sopra la natura del male da cut sono attaccate le bestic
bovine nelle Comunita di Firnignano e Savignano, di Vlgo e di Verzuno, di Burzanella e di
Montagti Ragazza, e di Camtignano (Promncta di Bologna). The manuscript written in 1775
was published by Giambattista Ercolani in the Giornale di Medicina veterinaria, 1860, I:
539 ; c) Deduzioni sintetiche su Felcttricita animale, was published on July 7, 1798 by Paolo
Predieri in Memorie delPAccademia delle Scienze delPIstituto di Bologna, 1861, XII: 36; d.
Dissertazione latina sopra Pazione delle mefiti nel corpo animale, was read before the Academy
on April 27, 1797 and published by Silvestro Gherardi in Memorie dtWAccademia delle Scienze
deiristttuto di Bologna, 1870, X: 478.
85 Archivio di Stato di Bologna, Studio. Acta ill. et ex Coll. Phil, et Med. Bononiae from
1753 to 1760, page 94.
XV111 INTRODUCTION
he was appointed alunno (student) at the Academy of Sciences of
the Istituto He practiced medicine and surgery in Bologna hospi
tals soon after but also found time for anatomical research. He was
appointed lecturer de Rebus medicis at the Archiginnaslo he had
attended, and on April 28, 1763 was made honorary lecturer. 37 In
the years which followed he taught surgery and theoretical anatomy.
On June 22, 1768 he became a Lectura stipendaria (paid lecturer) 38
and taught medical practice. He became Galeazzi's adjunct in anat
omy on December 12, 1775, under whom he taught practical
anatomy. 39 He held that office until the year of his death.
Galvani also taught at the Istituto delle Scienze. In March of 1766
the Senate of Bologna 40 made him Curator and Demonstrator of
the anatomical museum 33 which required him to give lectures and
demonstrations of anatomical operations before surgeons, painters
and sculptors. On February 26, 1782, that same Senate 41 appointed
him Professor of Obstetric Arts at the Istituto, a title which he held
for sixteen years. 42 In addition to these duties, he taught classes in
his home on pathological anatomy and was thus kept busy teaching,
investigating, and practicing medicine and obstetrics.
He joined both the Academy of Medicine and Philosophy and
several times was appointed rector or rector's councillor of each, and
on May 13, 1772^ as one of the benedettini of the Academy of Sci
ences, its chairman. His moral greatness was in complete harmony
with his intellectual stature. Contemporary writers and first biog
raphers describe Galvani as an honest, mild, modest man, polite,
charitable to the unfortunate and always a noble and generous
friend. Even in trying moments he showed unshakable strength of
character. He was a very pious man and showed fervor and reverence
in even the most detailed religious observances. According to Vella 44
86 Atti delle risoluzioni e dei decreti dell'Accademia dell Scienze dell'Istltuto di Bologna,
Fasc. 13.
87 Archivio di Stato di Bologna, Senato. Liber Partitorum from 1762 to 1769, 54: 38.
38 Ibid. 54: 163.
"Ibid. 55: 225.
40 Ibid. 54:108.
41 Ibid. 56:169.
42 Bacialli, L. Utnsegnamento della Ostetrlcia a Bologna dalle origini ad oggi t (1754 to 1950).
Bologna, 1950.
48 Atti delle risoluzioni e dei decreti delPAccademia delle Scienze deli'Istituto di Bologna,
Fasc. 1 6.
44 Vella, L. Discorso pronunziato aWinaugurazione del monumento a Luigi Galvani. Bologna,
1879.
INTRODUCTION XIX
religion had become his conscience. This made him interpret his own
art as a spiritual mission which he always followed with fraternal
love towards the sick.
At his preceptor's house, Galvani met the only daughter of the
famous anatomist Galeazzi, Lucia, whom he soon married. This in
telligent and learned lady shared many happy and anxious hours
with him for almost thirty years. 44 Her death on June 30, lygo 45 was
a blow from which he never recovered. His last years were bur
dened by more than emotional pains for he had the physical pains
probably caused by pyloric stenosis. 46
The most outstanding proof of his strength of character was shown
by Galvani during the final year of his life. When an edict of the
Cisalpine Republic, created by Napoleon, ordered that all public
officials take an oath of allegiance to its constitution, this great
patriot refused because he would not subscribe to a formula so con
trary to his principles: the oath was atheistic. By refusing to take
the oath he lost all his offices at the University and the Institute in
April 1798^ which reduced him to poverty in his last days. Pietro
Giordani wrote that "he neither suffocated the voice of conscience,
nor made it subservient to profit and ambition, but accepted pov
erty, losing without protest those academic offices which were his
very bread/' 48 His fellow citizens, and especially Giovanni Aldini,
appealed to the Government to remedy this injustice, and Galvani
was restored to his previous offices as emeritus professor, but the
decree was announced when death was about to take him. He died
at 6 1 on December 4, 1798, in the house of his birth to which he had
returned to live with his brother following the death of his wife. In
accordance with his will 49 his body was buried next to that of his
carissima wife 45 , in the Monastero delle Suore del Corpus Domini.
45 Lucia Galvani was buried in the Area delle Casse at the Corpus Domini on July 2, 1790.
By the will of Luigi Galvani, her body was exhumed and transferred to the burial place near
the original tomb. A parchment containing biographical data referring to Lucia Galvani was
written in Latin by Galvani and placed in her tomb at the time. This parchment, placed in a
lead container was found when her remains were exhumed in 1873. Dino Zucchini found a
copy of the original in 1937 (Zucchini, D. Elogio dettato da Luigi Galvani in morte della moglie
Lucia Galeazzi. Bologna, 1938.
48 Medici, M. Elogio di Luigi Gakani. Bologna, 1845.
47 Al principio di Fiorile Anno VI, according to Venturoli (2).
^Giordani, P. Opere. Vol. II. Florence, 1857.
49 Malagola, C. Luigi Galvani nelPUniversita, nell (Istituto e mil} Accademia delle Scienze
di Bologna. Bologna, 1879.
XX INTRODUCTION
There the two bodies remained neglected until 1873 when n the
30th of October, the City of Bologna transferred their remains^ to
a marble sarcophagus built in a special vault of the Church adjoining
the monastery. 50
During World War II, Sister Luisa, of the Convent of Saint Cath
erine where the Galvanis were buried, had a premonition that the
burial vault would be struck by an aerial bomb. She collected the
remains in small metal vessels and transferred them to the Church
of San Luca atop nearby Qsservama Hill A bomb demolished the
original vault. On July 27, 1947 the remains were returned to the
Convent where they await proper reburial in the badly damaged
holy site.
It is not civic apathy which has as yet prevented Bologna from
gathering into a worthy resting place the bones of its most famous
son, who, by devoting himself to the search for truth, has given his
name to all the languages of the world.
GIULIO C. PUPILLI
Director of the Institute of Human Physiology
University of Bologna, Italy
February 2, i<)53-
60 The Corpus Domini Church is commonly called della Santa, in commemoration of
Saint Catherine of Vigri, protectress of the arts, buried there.
Concerning the Origin and Development of the Theory
of Animal Electricity
Dissertation by
Giovanni Aldini
Dissertation of Giovanni Aldini 1
Concerning the Origin and Development
of the Theory of Animal Electricity
I. It is my purpose to portray briefly what was the origin, what
the development, of animal electricity, what the experiments per
formed tinder the leadership of Galvani, and to emphasize those
things which either preceded or followed that man's industry. Al
though animal electricity did not have the same beginnings as com
mon electricity, nevertheless it has undergone not dissimilar vicissi
tudes. That famous discovery of amber by Thales of Miletus 2 long
lay neglected until the fortunate age of Beccarius, Delibard, Wilson,
Epinus, and of him who is worth them all, Franklin, illuminated it
by their labors, the age which, with iron rods placed aloft, did not
fear even the thunderbolts of indignant Jove. Nevertheless, in the
memory of the fathers also, many observed phenomena were cor
rupted, partly by the perversity of the times, partly by the fables
of poets.
II. It escapes no one what Cicero, Livy 3 and Valerius Maximus
have handed down to memory concerning the flames observed about
the head of Servius Tullius; but the reputation of that prophetic
1 Distinguished physicist, nephew of Galvani. Born at Bologna, April 10, 1762; died at
Milan, January 17, 1834. In 1798 he succeeded Canterzani as Professor of Physics at the
University of Bologna.
Etymologically and genealogically the name Galvani is of French Keltic or Gaelic origin.
In the form of Galvain or Gauvain it was widely diffused during the early medieval centuries
through Brittany and Normandy. Thence by Keltic migration it made its way to Greater
Britain; to Lesser Britain in the form of the Irish Galvin and Gavin j and then to Scotland
in the form of Gawain. The most famous bearer of the name in this Scottish form was of
course Gawain, the son of King Lot of Lothian and Orkney, one of the most celebrated heroes
of King Arthur's Round Table. Finally at the Norman conquest of Sicily in the eleventh
century, the name and heritage were transferred to Italian soil and there became established
as Galvani. It is interesting that there is this hereditary and linguistic link between Arthurian
romance and this pioneer of electricity.
2 First of the Seven Sages of Greece, B.C. 636 to 546. He was the first to observe that
amber, when rubbed, attracts light bodies.
3 Titus Livius: Historia Rerum Romanorum: Book I., Cap. XXXIX, i. "Eo tempore in
regia prodigium visum even tuque mirabile fuit: puero dormienti, cui Servio Tullio fuit nomen,
caput arsisse ferunt multorum in conspectu."
2 DISSERTATION ON ANIMAL ELECTRICITY
fire had so spread among the ancients that Virgil 4 also celebrated in
his verses lulus, with the crown of his head surrounded by harm
less flames. From Hermolaus Barbaras and our own Aldrovandus 5
we have heard that ravens in their pernicious flight bear aloft a flam
ing beak in the midst of tempests; that eagles, at the fall of thunder
bolts are so surrounded with unwonted light that they shine gleam
ing in the sky like planets. Hence perhaps prophets have considered
that bird as sacred to Jove and minister of the thunder bolt; 6 which
interpretation was strongly approved by Guenau de Montbeillard,
who chiefly insisted on this, that the fables themselves derive their
origin from some fact.
But from all these things, electricity could be deemed not as in
nate in animals but merely communicated, whose action long before
had been expressed both by stars gleaming about the spars and
yards of sailors, and by fires falling into the night-watches of sol
diers, which Caesar 7 recalls when he reports that through the night
the spear-points of the fifth legion " burned of their own accord."
Therefore, setting aside electricity communicated to animals, we
will pursue that which is regarded as innate, first in animals gener
ally, and then in man.
III. Immediately there present themselves the celebrated experi
ments of Gordon, with which he embellished the well-known elec
tricity of the cat. For using insulating substances he collected as
much electricity as, conducted to the upper surface of vinous spirits,
produced very prompt flaming. Hartmann and Dubois, by making
light attrition, caused notable electric attraction in the feathers of
a bird which they call Kakatois (cockatoo). What shall I say of the
Torpedo which, safeguarded by its electrical explosions from injury
4 Aeneid II, 682.
"Ecce levis summo de vertice visus luli
Fundere lumen apex, tactuque innoxia mollis
Lambere flamma comas, et circum tempora pasci. JJ
5 Ulisse Aldrovandi. A celebrated naturalist of Bologna, 1522-1607 A.D. He wrote an
ornithology in three volumes, and three more treating of insects and mollusca; his botany
embraced sixty folios.
Cf. Hor. Od IV, 4, 1-4
"Qualem ministrum fulminis alitem,
Cui rex deoram regnum in aves vagas
Permisit expertus fidelem
Juppiter in Ganymede flavo."
7 DeBelloAfricano.VI.
GIOVANNI ALDINI 3
by larger fishes, converts those fleeing in consternation to its own
nutrition. The most recent observations of Walsh and Spallanzani
have made known the properties of Torpedo, ascertained by Aris
totle and Pliny. One of them recognized in it the structure of the
magic square, 8 electricity having been detected on its back from
excess, on its belly from deficiency; the other, at his preference,
prohibited concussions by interposing an insulating body, and noted
succussion not only in the Torpedo submerged in water, but also
in the foetus while enclosed in the maternal uterus. Vanderlot and
Bajonius discovered phenomena cognate to the Torpedo in the
electric Gymnotis (eels) living along the coasts of Surinam and
Cayenne. A few years from then, moreover, a family mated two
species 9 of electric fishes with itself; but if others are added by the
industry of the physicists, there will be new electric swarms of fishes,
whose incursions will be highly hostile to the swimming inhabitants
of the ocean.
IV. But there are not lacking terrestrial animals who seem to
rival to a high degree the electric virtue of the Torpedo. The cele
brated anatomist Cotunius with a knife cut the epigastrium of a live
mouse firmly grasped in his left hand, and suddenly had a very
violent concussion, which was transmitted with such force from his
arm to his shoulders and then to his head that immediately he had
to marvel at the phenomenon and throw the mouse away. But I
think the glory of the newly discovered electricity lightened for a
whole quarter-hour and more the pain incurred in his head and arms.
The industry of Vassalius and of others confirmed the observations
of Cotunius.
V. It would have been thoughtless of nature to deprive men of
the beneficent action of electric fluid, which she had granted most
abundantly to brute beasts. It had already been ascertained that
Camusius had prepared himself an electrophore, from dried nerves.
The bones of the head, on rubbing, have often shown me no slight
electricity. Saussurius, famous for many physical and mechanical
inventions, excited electricity in the living man by the lightest attri
tion: after taking a short walk, he wished to ascend an insulated
surface, and, having applied his hand to a light electrometer, was
immediately amazed at the divergent wires. Sauvagesius reports in
8 A name sometimes given to the quadrant electrometer or electroscope.
9 One of these is called "trembleur," the other is ascribed to the genus "tetrodon."
4 DISSERTATION ON ANIMAL ELECTRICITY
his treatise on hemiplegia, that the lower limbs of certain men gave
out an electric vapor after walking. Fougeroux, Bovilletus, and also
our own Laura Bassia, 10 have often noticed little flames breaking
out from human bodies, either when lingerie was being changed or
when silk garments were being donned in a very dark chamber.
When Symmerius doffed his stockings, he saw vivid electricity flow
ing from his legs: but when two silk stockings by which the same leg
was covered, one white the other black, were separated, opposite
electricity was immediately generated, so that indeed the former
became positively electric, the latter negatively. But these phe
nomena I should truly prefer to derive from friction, particularly
silk, than from native human electricity.
VI. Animal electricity has not rarely been seen to have dwelt in
intent eyes, studious of things. Bartholinus, 11 in his well-known
treatise concerning the light of animals, mentions a man whom any
one could easily recognize because more light shone from his eye
brows. Bartholinus adds that the eyes of hydrophobes have many
times become ignited, so that on that account he thinks it by no
means fabulous which the historians relate of Alexander the Great,
whom, in the midst of battle, the ardor of glory had so permeated
that his eyes also seemed to blaze. But, truly, let happier natures
pursue remote and lofty conjectures. Electricity has greatly pleased
the gravest physicists and physiologists in explaining the phenomena
of hydrophobes : they have not hesitated even from the optic nerves,
electricized by sudden rubbing, to derive distinct circles with various
colors of light, or bright points, commonly called stars, which are
excited when the eyes are struck by a sudden blow.
VII. Animal electricity has sometimes been regarded as a most
pernicious cause of some of the gravest crises of life. Hence those
very unfortunate explosions described by Masseius, Bianchinus, 12
10 Laura Maria Caterina Bassi, a learned Italian lady of Bologna, 1711 to 1778, a doctor
and professor of experimental science at Bologna University. She married a physician, Giuseppe
Verrati, and had several children.
11 Gaspard Bartholinus, a learned Swede, of Malmoe, 1585-1630, who studied at the
Universities of Copenhagen, Rostock, and Wittemberg, and became successively Professor
of Medicine and of Divinity.
Thomas Bartholinus, son of Gaspard, born at Copenhagen in 1617. He studied medicine
at Leyden; studied also at Paris, Montpellier, Padua, and Basel. He was Professor of Anatomy
at Copenhagen from 1647 to i&>if studying particularly the lymphatics, and the vulvo-
vaginal glands which were named for him. He died on December 4, 1680.
ia Francesco Bianchini, a noted Italian astronomer and antiquary, born at Verona, De-
GIOVANNI ALDINI 5
and Wilmer, which, while men were enjoying a clear sky, suddenly
brought them to horrible death, pulverized to powder; these bed
time thunderbolts, as they call them, many physicists refer to the
same animal electricity: but truly we should be less disturbed if, in
explaining so great a matter, they would not reject the association
of other forces. But it is easy for us to refrain from these conjectures,
lest, by ascribing all phenomena to electricity, confidence finally be
diminished in those in which it is really concerned. Let us therefore
pursue what belongs to our intention, those things which merely
evince the certain existence of animal electricity.
VIII. Bridonius, in a written communication to the Royal Acad
emy of London, discloses a delicate electricity of the hairs. Every
device looks to this end, that there should be two men, of whom
one sits on a conducting surface and displays to the other, who is
insulated, the countless hairs on his chest to be separated. Thereupon
the insulated man becomes as it were the conductor of an animal
electricity machine: hence from him vivid sparks streamed, whence
vinous spirit was ignited and a Leyden jar charged, which greatly
moved those who were present at the observation. But in this, two
things are particularly to be guarded against, one that no powder or
ointments be used by the hair for its nourishment, the other that
when sparks are to be sought, the experiment be done in an extremely
dark chamber, lest the brilliance of the animal electricity excited be
obscured by the external light. Although these things pertain to the
more recent theory of electric vapor, yet they have not been able
after many years to displace the sagacity of the celebrated Mairani
who had adequately explained the electricity of hairs by his ob
servations.
IX. Electric vapor, hitherto elicited, was not limited to human
integuments but also dominated widely in the internal human mech
anism. Vassalius and Volta, with the highly mobile electrometer of
Tiberius Cavallus, discovered that a large amount of electricity is
associated with the urine of man. Michael Pushkin, 13 when Tobolski
was in good health, communicated an electric spark to those who
touched him. Lassinius relates that in Florence he perceived phe-
cember 13, 1662; died at Rome, March 2, 1729. He was educated at Padua, and devoted
himself especially to the classics and mathematics* His last work was a series of observations
on the planet Venus, entitled "Hesperi et Phosphori Nova Phaenomena."
18 Younger brother of the poet, Alexander Pushkin.
6 DISSERTATION ON ANIMAL ELECTRICITY
nomena in a Russian man closely cognate to the electric property
of the Torpedo : Gaubius teaches in his pathology that he had ob
served this in a certain patient long before. Behold, transmitted
even to human beings, wonderful properties which nature seemed
to have imparted to the Torpedo alone!
X. The subjects which we have thus far pursued, great and im
portant though they are, seem nevertheless to be far distant from
the recently detected Galvanic electricity. Certainly the electro-
phores made of dry nerves or bones do not prove it, nor sparks
breaking from hairs, or limbs, or integuments. For since almost all
bodies destitute of moisture in some way become insulating, and
since skin and hairs evince a non-conductile nature, there is no
reason to wonder why some electricity arises with attrition, which
ought more truly to be called artificial than natural. In the previous
observations, Saussurius declared the power of artificial attrition,
who failed to get electric attraction in a man who was insulated by
no clothing causing attrition. But that the remaining phenomena,
which we were discussing, it should appear, are not to be confounded
with animal electricity, it should be more deeply explored, and more
diligent investigation made into Galvani's theory.
XL Now Galvani's Commentary has four parts, of which the first
and second explain the power of communicated electricity, the third
describes electricity intrinsic in animals and producing muscular
motions, and the fourth proposes some conjectures and corollaries.
As for what pertains to the first and the second part, although it
had become known to physiologists that artificial electricity was
most potent for exciting muscular motions, they had been accus
tomed to apply it to the muscles to be excited. But, what no one
had attempted before Galvani, was now accomplished by his sa
gacity and ingenuity, that we may have muscles disposed to con
traction by the mere passage of a spark, although they may be either
situated far remote from the conductor, or surrounded on all sides
with sheets of glass. And those contractions in enclosed frogs remote
from the conductor are excited by the action of either artificial or
atmospheric electricity. And yet, while Beccaria's 14 celebrated theory
14 Giovanni Battista Beccaria, celebrated Italian mathematician and physicist. Born at
Mondovi, Piedmont, October 3, 1716; died at Turin, May 27, 1781. He was Professor of
Physics at the Universities of Palermo, Rome, and of Turin, and especially noted for his
researches in electricity. He was elected a Fellow of the Royal Society of London in May,
1755-
GIOVANNI ALDINI 7
of electric vapor stood valid, the existence of intrinsic and native
animal electricity could always by strict reasoning be derived from
the action of extrinsic electricity. For muscles immersed, for ex
ample, in an atmosphere of extrinsic positive electricity, cannot
themselves escape being electrified unless they find the opposite
electricity, or exude electricity introduced into them; while this is
happening, muscular motions are excited. Therefore communicated
electricity does not itself produce the contraction, but, disturbing
from its equilibrium the electricity in the muscles, conduces to the
production of contraction. So that from the first and the second
part of the Commentary we learn how often the electricity in muscles
is itself disturbed and moves the muscle.
XII. But if perchance to anyone the proposed reasoning should
seem too presumptuous, let him not therefore despise the experi
ments on which it depends, or especially on that name, which first
showed Galvani the distinguished pathway of discovering intrinsic
animal electricity. Therefore there is no reason why we should seek
from selected conjectures that which the third part of the Com
mentary vindicates on its own right by new observations, and which
is supported and demonstrated by experiments. Hence it will readily
appear that to the same term of animal electricity, which we have
used above, ought to be added hereafter a new force and signifi
cance according to Galvani J s discoveries. For he himself is our
authority that only that should be considered true animal electricity
which is spontaneously excited in warm or cold-blooded animals,
with no approach of artificial electricity, no attrition, and no per
cussion, which accompanies the final functions of life, and which
has between muscles and nerves an easy and calculated course, flow,
and circuit. But to this animal electricity is entrusted that noblest
duty, that it should supply the functions of the animal economy and
accomplish the muscular movements, of which the former could
easily be inferred from the affiliated phenomena of the Torpedo and
other animals, but the latter is wholly a new consequence of Gal
vani 's observations.
XIII. But all experiments finally come down to this: that, if all
action of extrinsic electricity be excluded, if the nerves and muscles
are intact and only a metal arc is applied, vigorous contractions
occur, which fail completely, if one end of the arc is wrapped in an
8 DISSERTATION ON ANIMAL ELECTRICITY
insulating covering. But those precautions which we provide for
ourselves for assisting the action of artificial electricity, the same
augment to a remarkable degree the power of animal electricity also.
It is truly amazing how much various metallic armatures placed on
nerves and muscles assisted Galvani to extract animal electricity.
Not merely one, but a twofold, electricity dominates in the animal
machine, by excess and by defect, and if, by an artificial arc, they
are brought into an equilibrium, then muscular motions cease. In
living animals the lack of an artificial arc is supplied by animal
humor, suitable in the first instance to convey electricity and bring
it to an equilibrium. But if this principle, which flows through
friendly conducting bodies, whose too rapid excursion is checked by
insulating bodies, which obeys the law of equilibrium, if it is not
electric, what will be hereafter the bodies in which we think the
electric principle resides?
XIV. But electricity cannot be propagated through bodies of
different conductivity, without experiencing some difficulty of
transit. Hence Galvani was aided by armatures prepared from differ
ent metals, chiefly for the extraction of animal electricity. To him,
scrutinizing the more intimate cause of so great a phenomenon, it
seemed that he should have recourse to certain as it were chemical
properties of electric vapor. The more recent physicists consider
electricity harboring in bodies just like a fixed fire, latent heat,
phlogiston, or caloric. In their opinion a certain electricity is present,
which contributes as an element to the intimate composition of
bodies, and cannot produce its own effects unless it is freed from the
bonds of closest connection and even of established affinity: hence
in electric vapor phenomena occur analogous to those which Wilkie,
Blake, and Crawford have recently brought forward concerning
latent fire and the varying aptitude of bodies for containing heat.
Truly the diversity of metals, which is so potent in augmenting
contractions, confers great probability on alleged suspicion. Leaves
of gold-foil, prepared with other metal armatures combined, not
rarely excite little or no electricity in animals. But this very varied
faculty itself, which metals have for receiving and exciting electric
vapor, what else does it indicate, if not that bodies are so prepared
by their own nature to receive electricity into themselves diversely?
How indeed, if two bodies are endowed with the same capacity, as
they say, is warmth in equal degree established at an equilibrium in
GIOVANNI ALDINI 9
both? So, if homogeneous metals are used, that is no reason why the
electricity should betake itself to one more eagerly than to the
other, so that on that account, no effort being devoted to equilib
rium, no more violent contraction also should arise.
The highly ingenious Thouvenel 15 seems to apply his mind to the
proposed conjectures, for he reports at the same time that he has
very often observed animal electricity excited in men, who, in ac
cordance with his well-known method, were standing in metal mines.
But obviously it is difficult to define to what metal you would assign
the foremost part in evolving animal electricity. Nevertheless the
illustrious Volta, 16 guided by the most accurate observations, de
vised a definite classification of metals, which he reduces to three
groups: the first includes mercury, gold, silver, and platinum; the
second iron, bronze, and copper; and finally tin and lead.
XV. But the study of experimentation in animal electricity was
not limited to the confines of Bologna but, spreading more widely
in every direction, extended far to foreign Academies also. So that
animal electricity which we have pursued above first in brute beasts,
then in man, now again in the same order presents itself to be ex
plained by the observations of Galvani. Birds, fishes, very many
reptiles display electricity conspicuously.
If an eel is cut transversely, as the most expert observations of
Eusebius Valla and Mesinus report, and the spinal cord armatured,
immediately the tail trembles vehemently for thirty minutes, then
with perceptibly weakened motion, and finally comes to rest when
forty -five minutes have not yet elapsed: the armatured head of an
eel gave sluggish but longer contractions, which appeared for fifty
minutes.
In two tenches, with the spinal cord armatured near the head, the
fins were moved five or six times, but after two minutes afforded no
15 "Metals, and also mines, have proper or spontaneous atmospheres of electricity, which
differ among themselves by their intensity, and are even opposite in relation to their de
terminations, effluent or affluent, centrifugal and centripetal, positive and negative, or mixed:
and consequently mines and metals ought not to be considered solely as simple conducting
bodies, or conductors of communicated artificial electricity, but as true motor means, ex-
citators or condensers of spontaneous or natural electricity, a property which they possess
also to very different degrees." Letter from Thouvenel to AmorettL
"Count Alessandro Volta of Como. Born February 18, 1745. Died at Paris March 5,
1827. Professor at Como and Pavia. Inventor of the electrophore, the electroscope, the con
denser, and the voltaic pile.
IO DISSERTATION ON ANIMAL ELECTRICITY
motion. The wings of a chaffinch were slightly contracted for three
minutes, but not so the legs. In a newborn cat, motion was obtained
only in the forelegs for a quarter of an hour. In a dog stricken to
death with a pinch of pear-powder, the four legs having been pre
pared and insulated, contractions were excited when a metallic arc
was applied : the hyoglossus and genioglossus muscles trembled vio
lently, but the laryngeal muscles, being prepared with the well-
known armature, far less. Lizards and turtles afford equal
phenomena; then insects also, and almost all kinds of animals were
subjected to the same observation with no different result.
XVI. We recalled that vipers had not yet been tried for first
examination, and we were perhaps principally attracted by this,
because from their peculiar structure they seemed to promise the
most electricity : the outcome did not deceive or fail our preconceived
expectation. Their integuments having been reflected, the vipers,
indued along the vertebrae with a tinfoil armature, produced vigor
ous muscular motions with a metallic arc. But the natural move
ments of vipers, and the violent spontaneous contortions excited in
the whole body, seemed to afford some suspicion and ambiguity in
animal electricity. Therefore, in order that I might determine
whether the excited motions were really electric, I cut the spinal
cord transversely in several places, and having made an armature
on the nerve-filaments, which are very numerous along the verte
brae, I saw constant muscular movements, which lasted a long time,
if the animal moisture were maintained. That I finally remedied,
so that the armature close to the vertebrae was somewhat extended
outside them by an insulating body; and from this it resulted that,
when an arc was applied to the tin armature and to the silver plate,
vigorous contractions occurred from intact nerves and muscles.
When we practised the same method in the country, we transferred
to the cut section of a dead snake, whose length exceeded two feet.
But if the vertebrae were armatured and an arc applied, not one,
but repeated, and as it were perpetual, contractions arose most
violently.
XVII. But, not to go too far afield, I will mention here the no
blest invention of Volta, whereby he applied a harmless method of
safeguarding the life of any animals and at the same time of experi
menting] with electricity. Hereafter, therefore, for any comparison
of animal electricity, there will be no need of sacrificing any victims,
GIOVANNI ALDINI II
or of reflecting integuments and separating nerves with bloody
hands: it will be sufficient that spry, living frogs should sit on a silver
plate, indued along the vertebral column with a tin armature. For
when an arc is applied, contractions immediately are most vigorous.
We placed frogs on a silver plate, with a silver armature also applied
along the vertebral column; no contractions arose: and the same
result occurred when a living frog was equipped with a double
armature of tin-foil to his nerves and to his muscles.
XVIII. But it must be thought that the electric principle, that
it may be easily understood from those things which we shall soon
submit, was not added by accidental causes, but was intentionally
implanted by nature: and we see that the power of this principle is
so great that poisons themselves can quickly destroy life, but can
by no means extinguish animal electricity. Vallius shut up several
animals in various containers, so that he compelled them to inhale
the more pernicious gaseous fluids; sometimes he employed inflam
mable, sometimes nitrous or other mephitic gas; never was animal
electricity destroyed. One gas, contaminated by combustion of sul
phur, proved very noxious to animal electricity, and this perhaps on
account of the injuries which the elements of the muscle fibers had
sustained while it was acting.
Moreover, in some frogs, killed by the violent shock of a Leyden
jar, no changes in animal electricity occurred; but it always sur
vived when opium, powdered nicotine, or arsenic was administered
to frogs.
Galvani also several years later pursued the influence of opium
on animal electricity in a Dissertation which he delivered in the
Academy of the Institute of Sciences. Frogs, as is gathered from this,
when opium is administered either in the stomach or in the ab
dominal cavity or even introduced within the cerebrum, after a
great lethargy is excited, were affected with violent convulsions,
either from a slight tremor of the surface upon which they were
resting or from the contact of some body. These phenomena also
(which is indeed surprising) were not lacking, when the head was
cut off before the administration of the opium.
XIX. But it is pleasant to disclose to what end the physicists and
physiologists have undertaken so many labors and ingenious at
tempts. For since man is the chief of all animals, and since previously
so many victims had been sacrificed principally for the sake of dis-
ia DISSERTATION ON ANIMAL ELECTRICITY
covering his electricity, it was worth while that we should have
human electricity explored and revealed in fact and not by conjec
ture. Therefore to Galvani nothing was more important than that
with surgical dexterity, in the public hospital of Saint Ursula, he
should subject an amputated arm and foot to his experiments.
Wherefore an armature was placed on exposed nerves and muscles,
so that the nerves communicated with mercury, the muscles with
tepid water. When a metal arc was carried from a muscle to the
nerves vigorous contractions suddenly arose; but it was ascertained
by experiment that it is not nerves, but that by its mere contact
with the nerves, the same fairly strong contractions are excited,
which very thing had been detected also elsewhere in the lamb, in
the calf, and in other animals, especially the warm-blooded. But in
order that it might become known to Galvani that the cause of those
muscular motions was contained in electricity, he armatured the
nerves sometimes with glass, sometimes with resin, sometimes with
substances woven of silk: immediately all contraction was arrested.
Again he had recourse to the customary armature, and applied the
metallic arcs to the insulated nerves, and, to the utmost admira
tion of those who were present, saw the digits of the foot and the
hand, as often as the arc was applied, not merely contract, but relax.
It ought not to be passed over in silence that our author had obtained
more notable contractions, particularly when he applied armature
to the smaller nerve branches. But contractions of the foot far sur
passed those which were observed in the hands, either because the
feet possess more notable nerves or because the hand tested had
suffered more damage from longer disease.
XX. The fortunate outcome of surgical operations in the Hospital
brought a persistent patient, suffering from an inveterate ulcer in
his foot, to such a point that, changing his plan, he surrendered his
foot for amputation with surgical dexterity. Hence a new oppor
tunity was given of testing animal electricity. Therefore, following
custom, since we had previously debated together the method of
undertaking the experiment, I betook myself to Galvani to the
Hospital where, from the beginning of our observations, the thing
turned out contrary to our expectation. For when the nerves and
several muscles had been exposed, and various kinds of armature
had been tried, not only on the larger but also on the smaller nerve-
GIOVANNI ALDINI IJ
trunks, contractions were lacking, so that I wondered and almost
complained at so great variation from experiments previously under
taken. Meantime it was reported that that form of disease had ex
isted in the foot for seventeen years, that the foot, almost wholly
consumed by horrible emaciation, had lost almost all motions, along
with sensation: and already there were concretions here and there,
rough and very hard, and livid integuments, and the whole aspect
of the foot was such that those professors of surgery who were then
present, having taken consideration of all these things, thought that
animal electricity was not to be expected. Nevertheless, although so
many obstacles had arisen, there still persisted in my mind some
hope of observing electricity, which I could not cast away unless
first all ways of testing had been thoroughly explored, and the thing
had always turned out the same way; and I did not regret the
decision I had taken.
For when a layer of callous and fatty substance 17 had been re
moved from the sole of the foot, a nerve from the common nerve of
the foot 18 presented itself relatively free from injury: moreover,
when this nerve was armatured, vigorous contractions occurred
there to the nearest toes, (just as Galvani had noted), on the mere
application of a metallic arc to the nerves. Moreover we placed the
armatured nerve first on mercury, next on a silver surface, next on
gold always very vigorous contractions arose; it is indeed remark
able how much metals of this sort contribute to the assistance of
animal electricity. These observations having been made, I again
summoned with a more felicitous outcome the companions of my
experiment, whom I had previously dismissed; nay, while I was
greatly admiring the animal electricity, I drew the reflected integu
ments back into place, so that they covered the separated muscles
and nerves, and I took care that, by sprinkling rags with water, the
internal moisture of those parts should be preserved as much as
possible, so that thence it might be permitted to learn the durability
of animal electricity. Wherefore, after two hours had elapsed, I be
took myself again to the Hospital and, the armature having been
arranged, it was possible for some weakened contraction still to be
seen, which, gradually languishing, was shortly extinct.
17 Presumably and probably the plantar aponeurosis.
18 Medial plantar branch of the tibial.
14 DISSERTATION ON ANIMAL ELECTRICITY
XXI. Sulzer 19 an industrious man, had already noticed many
years ago that, if two sheets of different metal were alternately
applied on the tongue, a certain taste is produced, like that which
accompanies the sulphate of iron; and he thought that the metal
dissolved by the tongue claims for itself no part in this. That phe
nomenon, as the times went, it was endeavored to explain by a
certain vibration excited, of one metal, or of the other, or even of
both, which, striking the nerves of the tongue, produced some sensa
tion in taste. The illustrious Volta first of all referred Sulzer's ob
servation to the theory of animal electricity, and embellished it so
that he seems almost to have made it his own. Moreover, almost for
this reason, there arose an investigation which subsequently illumi
nated a most useful truth. Namely nerves, joined to conducting
bodies, pour out an electric vapor which, if it should be restored to
the muscles to which it was going, will excite either a contraction or
some impression. Therefore nerves should be sought in man which
lie so extrinsic that they can easily be armatured with metallic foil:
in Sulzer's observation, the tongue afforded these, which, by its
moisture, provides a most convenient path for latent electricity.
Hence, if tin-foil is fitted to the tip of the tongue and a silver sub
stance to its dorsum, when an arc is made between both armatures,
electricity is produced there, which excites only the most delicate
vapor, sometimes distinct of flowing acid, sometimes even it imitates
a disagreeable sensation: this experiment can most conveniently be
done by carrying a silver body, covered with tin, from the dorsum
of the tongue to its tip.
XXII. We ought not to pass over here the ingenious suspicion,
which has arisen or rather been renewed, which had been already
advanced before against Sulzer's observations. Truly, although the
power of the saliva for dissolving many substances is great, it is
very doubtful whether by chance it would join to itself any particles
which would excite the sensation of a definite taste. In order that I
19 Johann Georg Sulzer, a Prussian-Swiss philosopher and professor of aesthetics. He
was born at Winterthur, Switzerland, October 5, 1720; and died at Berlin, February 27,
1779. His chief work is his "General Theory of the Fine Arts." In his "New Theory of the
Pleasures," he says: "If one joins two pieces, one of lead and the other of silver, in such a
way that the two edges make the same surface, and if one approximates them on the tongue,
one will perceive from them some taste, fairly approximating the taste of sulphate of iron.
Whereas each piece separately gives no trace of this taste. The only probability is that from
this junction of the two metals, there occurs some solution of one or of the other, and thaf
the dissolved particles insinuate themselves into the tongue." 2
GIOVANNI ALDINI 15
might avert as much of that suspicion as was in me, after applying
the customary armature to the tip of the tongue, I applied a metal
arc interrupted with insulating substance: but rarely slight, and
generally no taste arose, which on the contrary, merely considering
the saliva dissolving metal, would always have been expected. While
I was meditating these things, I learned from a most welcome mes
senger that the illustrious Volta, by a new and most ingenious ex
periment looked forward to the security of his observations; for he
accomplished the production of tastes, even though all communica
tion of the tongue with metal was cut off,
Therefore he immersed the tip of the tongue into a level of water,
in which he had placed a scrap either of tin or of paper covered with
tin : when a metal arc was carried from the middle of the tongue to
the tin layer, the sensation of an acid taste was excited, which con
tinued to be felt, as long as the contact lasted. That, in the pro
posed experiment, the certain action of electric vapor might be better
confirmed, we substituted oil of almonds for water: when the arc
was employed, according to custom, no taste arose. Hence it seems
that it can be inferred that the tongue perceives the taste not of
dissolved metal but of the electricity running out through it.
XXIII. Moreover, the diversity of metals (as we have carefully
noted) produces great varieties in striking upon the organ of taste.
Armatures, prepared from silver and from tin, are most suitable for
producing tastes. With homologous metals, the action of animal elec
tricity is either diminished or wholly prevented: wherefore, if a silver
armature is applied to the tip of the tongue and to its dorsum, no
taste is excited; the same thing happens, if you use tin on both sides.
But by experimenting, we discovered that this is least suitable for
exciting the impression of taste, that the arc should extend from the
armatured tip of the tongue to the dorsum. For if from either the
arm or the foot immersed in water, or merely from the water-level
in which they are, an arc is made to the tip of the tongue covered
with tin, vivid taste is immediately excited; but perhaps it will be
even more vivid, if the whole animal machine is immersed in water
and a metal arc employed, which by its thickness and length in
some way invites animal electricity, and can drain it more con
veniently. But, leaving these of ours, let us revert to the most illus
trious observations of Volta.
XXIV. Great phenomena have followed the taste excited in the
1 6 DISSERTATION ON ANIMAL ELECTRICITY
corollaries have derived. For it was ascertained that, by changing
the armatures in turn, the tastes are changed also, so that some times
the taste becomes not acid, but bitter and burning, which formerly
came very near an alkaline nature. These things having been per
ceived, Volta readily changed to this opinion, so that he thinks it is
completely confirmed by the new experiments that there resides in
metals the power not merely of conducting but of exciting electricity.
Wherefore now, indeed, and deservedly, a distinguished man is to
be congratulated, because, if I may say so, he has amplified the
domain of animal electricity, although he has applied it not to per
forming muscular motions but also to producing sensation. For the
nerves which serve not only motion, but also sensation, obey animal
electricity, so that on this account the mind, with its own safety as
a judge, excites either motion or sensation. Hence Volta, having
removed the entire tongue from a lamb, and made a double arma
ture, and applied one to the nerves at the root of the tongue, the
other to the corresponding muscles, as soon as an arc was applied,
obtained very prompt muscular motions. These were the experi
ments of animal electricity instituted in brute beasts and in man,
which anyone will easily understand differ widely from those which
had preceded the industry of Galvani.
XXV. In the fourth part of Galvani's Commentary, he reasons
from certain and explored facts to probable conclusions and con
jectures, prepared with all sagacity and industry. To anyone weigh
ing carefully the experiments of the first and second part, it will be
clearly convenient to explain the remarkable influence of atmos
pheric electricity on the animal economy.
Moreover, as Bartholinus teaches, nature seems to have used
two media particularly for communicating electricity to the animal
economy. First she causes that the universal integuments of the
human body should abound with innumerable pores, by which elec
tric fluid may be communicated to animals, whether it were from
excess in the atmosphere or from deficiency in the body. Further
she provides that, by means of respiration, a new supply of elec
tricity is constantly taken to the lungs, where, as if having found a
convenient secretory organ, it is extracted from the air, with which
it was combined.
XXVL Moreover, in accordance with the varied ratio of equilib
rium whereby internal animal electricity may be related to extrinsic
communicated electricity, it is necessary that the influx of atmos-
GIOVANNI ALDIHI IJ
pheric electricity should be varied. Hence it will appear why, when a
great storm has arisen in heaven, or immense rains have fallen, some
times the animal machine becomes more active, sometimes in cer
tain patients the symptoms of their malady become more severe.
And it will not seem surprising, as reported by Woodward, that
certain men have existed, who, before thunderbolts, seemed to suffer
immense anguish, and felt their precordia oppressed, and were even
compelled to vomit. Beccaria relates that he knew a certain man
named Maceas, who, when the sky lightened and thunder rampaged,
was seized with most distressing attacks of epilepsy. "Hence lethargy
is easily perceived," says Gardiner, "on certain definite days in
which artificial electricity is excited with great difficulty." For lassi
tude, sadness, melancholy, and hysterical manifestations, at certain
definite times especially indicate and openly demonstrate that all
nervous diseases have relationship with the atmosphere. But the
influx of atmospheric electricity is not always harmful and to be
feared. The more abundant transpiration of communicated elec
tricity produced can be beneficial, and the prompter and more ex
peditious excursion of the humors can be of the greatest advantage,
to the animal economy. Hence, with a serene sky and placid elec
tricity, we also enjoy, as I may say, a certain most welcome alacrity
of our powers, which we do not experience when lower electric clouds
hang over us.
XXVII. Now it is extremely difficult to define and determine
whether the action of atmospheric electricity thus far considered
derives merely from one law of equilibrium, or from other causes
also. Mahoney introduced a new sort of rebounding electricity, which
nature had previously demonstrated by the conspicuous phenomena
of thunderbolts. It is stated in meteorological histories that men
have often been destroyed by a thunderbolt which they were watch
ing at some distance as it roared in heaven. In Bennet's most delicate
electrometer we have most conveniently observed rebounding elec
tricity, with the physicist J. B. Venturius, in different metallic
leaves placed under it, whose further remarkable properties he so
pursued that he easily transferred it to explain phenomena which
are propounded in the first and second part of Galvani's commen
tary. With other experiments also, initiated in the same Bennet's
electrometer, he thinks he can determine the reason why the contact
of a metallic body should move inherent electricity in animals.
XXVIII. But with new knowledge of animal electricity hereafter,
1 8 DISSERTATION ON ANIMAL ELECTRICITY
and investigation of certain symptoms, some light will necessarily
arise for the cure or palliation of certain diseases. Tetanus, epilepsy,
convulsions, various diseases of the nerves, as Galvani notes, exhibit
many phenomena which demand an understanding of electricity.
Surely, if electric fluid produces muscular motions, if the whole
animal machine is primarily operated by its action, it is clearly
understandable why, in either excess or deficiency of electric powers,
various differences of health should arise. But these things will be
perceived by the more sagacious physicians, to whom they pertain.
XXIX. Galvani 's theory seemed to produce some vicissitudes in
Haller's 20 theory of irritability. For electricity, which to the Hal-
lerians was merely an external stimulus, now becomes intrinsic in
ourselves. For muscles constitute the most delicate electrometer of
all, to which a moving cause is always attached by law and institu
tion of nature. Therefore what the Hallerians assume by the term
of irritability should be defined. For if they mean nothing else but
a new phenomenon of nature, or property inherent in fibres, whereby
elements approach one another, then there will be no conflict be
tween the systems of Galvani and of Haller, but future correlation
may be expected. For Galvani not only conceded that property to
be inherent in muscular fibres, but considered it so necessary that,
in its absence, wherever an arc was applied, you could not excite
animal electricity. But if, by chance, to the Hallerians irritability
is a new power inherent in fibres and producing muscular motions
by itself alone, then surely one cannot acquiesce in their opinion,
unless first they demonstrate the existence of irritability, and them
selves prescribe definite laws, without which its true power cannot
be understood: all which truly they are confident they can accom
plish without difficulty, who demand the sole action of animal elec
tricity. But already we have made sufficient statement about these
things elsewhere.
XXX. But although, up to this time, very little exploration had
been done, as to whether animal electricity should be regarded as a
stimulant, or as the effective cause, of muscular motion, it was
nevertheless always established that the mind, in making contrac-
20 Albrecht von Haller, most eminent of Swiss anatomists, biologists, and physiologists;
born at Bern, October 16, 1708, and died there December 17, 1777. He studied at Basel,
Leyden, and Tubingen; was professor at Gottingen from 1736 to 1753; and practised in Bern
from 1729 till his death. He was thrice married, and left eight children: he was also a philoso
pher and a poet.
GIOVANNI ALDINI 1 9
tions, employs it as the handmaid of its authority, which surely had
not been demonstrated before Galvani.
Sauvage and Bonnet, 21 illustrious men, had indeed suspected that
electric fluid prepares muscular movements, chiefly because they
had perceived that vigorous contractions are excited in muscles by
artificial electricity. I remember also that in our Anatomical Theatre
my uncle once and again so contended for the power of electric fluid
in producing muscular motions that he seemed already, even at that
time (as if he divined the outcome), to be striving for that in order
that a hypothesis very dear to him might be converted into an ap
proved thesis. But though all authorities granted their praise, there
was no one, interested in physiological matters, who did not desire
a more abundant confirmation of the truth. There were not lacking
also those who applied all condemnations of hypotheses on elec
tricity, perhaps not noting that other physiological opinions ad
vanced were also hypotheses. Meanwhile, although at first nature
offered difficulty to the sedulous investigator, yet when questioned
more and more times, she responded to his wishes and diligence with
unexpected cumulative reward of his antecedent labor. Finally bright
day shone on Physiology and on Galvani, when he was able not only
to produce and explain animal electricity, which he had formulated
in his own mind, but to see it with his own eyes, handle it, and
direct it where he wished.
XXXI. But when Galvani's Commentary had barely been pub
lished, an occasion of illustrating the theory of animal electricity
presented itself most opportunely. For a studious youth, who had
begun to be intensely fond of animal electricity, insistently de
manded from Galvani that when, in accordance with his established
plan, he had decided to demonstrate Neurology publicly, he should
undertake in his lecture also to explain and illustrate the new sys
tem. Hence with a great multitude of auditors the physiological
exercises were held, to which were added the experiments which
illustrated the proposed part of the theory. Galvani never dissimu-
latingly avoided the accusations which had been made against ani-
21 Charles Bonnet, eminent Swiss naturalist and philosopher, born at Geneva, March
13, 1720; died at Genthod, May 20, 1793. He studied law, and in 1743 became a LL.D. and
a Fellow of the Royal Society. But he devoted his life to study of the natural sciences, and
wrote many books in these disciplines. Of nerve fluid he writes: "The physiologists, who
believe it analogous to the ether or to electric fluid, base their belief on facts and curious
experiences, which all appear to testify in favor of the electric nature of nerve fluid.*'
2O DISSERTATION ON ANIMAL ELECTRICITY
mal electricity, but exposed them candidly in his public lecture, and
estimated them with modest criticism, which was prompted not by
disparagement of another's industry, but solely by love of truth.
But I, since at that time I was most gratefully assisting my beloved
uncle in the public performance of experiments in Physics, could
not refrain from asking him, in my own name and that of the others,
that, should an occasion again present itself of publishing his Com
mentary, he would himself amplify and enrich it with the more
recently performed experiments and proposed conjectures. Since he
could not undertake this, detained by other business, he consented
that I should do it, and kindly communicated many data, which
furnished the argument of added notes to the Commentary. More
over, it was most acceptable both to gratify Galvani, to whom I
owed most, and at the same time to look forward to augmentations
of the theory of animal electricity.
XXXII. Finally, in the Fourth Part of his Commentary, in order
that he might leave nothing untried, Galvani prepared muscular
fibres and absolutely confirmed his hypothesis, both by its simplicity
and by its felicity in explaining the more difficult phenomena of
muscular motion. But what behoves them who profess to be lovers
of truth, and really are, is that each should not arrogantly trust too
much his own opinion, but be ready to relinquish it easily, if only
he perceives another more probable. And this I mention, not merely
because I think their counsel should be approved who, when they
apply themselves to investigating the laws of animal electricity, if
perchance they encounter any offense of obscurity, immediately
condemn and reject, with a more severe precipitate judgment, every
thing which proves its certain existence. For if the repute and in
tegrity of philosophic opinions were brought into conflict, when only
a slight doubt is proposed, we should have very few or none of those
theories which are the moderators and guides of human under
standing. Wherefore they seem better to have provided for their
name and fame and for the utility of physiology who judged that
their minds should be not downcast by the empty fear of difficulties,
but invited to glory by the sweetest reward of prospective praise.
If the fear of contradiction had from the beginning deterred the
illustrious men who first thought out the circulation of the blood,
we should have lacked that noble discovery, and many things which
are now clearly revealed in Physiology would still have lain in dark
ness.
Commentary Concerning the Effects of Electricity
on Muscular Motion
by
Luigi Ga/vani
Concerning the Effects of Electricity
on Muscular Motion
In my desire to make that which, with no inconsiderable expendi
ture of pains, after many experiments, I have succeeded in discover
ing in nerves and muscles, so far useful that both their concealed
properties might be revealed, if possible, and we might be able more
surely to heal their diseases, nothing seemed more suitable for ful
filling such a wish than if I should simply publish my results, just
as they are, for general judgment. For learned and eminent scholars,
by reading my discoveries, will be able, through their own medita
tions and experiments, not only to amplify and extend them, but
also to attain that which I indeed have attempted, but perhaps have
not fully achieved.
It was also my desire not to publish this work in a crude and barely
incipient form, even though not perfect and complete, which per
haps I should never have been able to do. But since I realized that
I had neither time nor leisure nor ability sufficient to accomplish
that, I preferred rather to fall short of my own very reasonable
desire than to fail the practical value of the work.
I thought, therefore, that I should be doing something worth
while, if I reported a brief and accurate account of my discoveries
and findings in the order and relation in which partly chance and
fortune presented and partly diligence and industry revealed them
to me; not so much lest more be attributed to me than to fortune,
or more to fortune than to me, but that either I might hand on a
torch to those who had wished to enter this same pathway of experi
ment, or might satisfy the honest desire of scholars who are wont to
be interested in things which contain some novelty either in origin
itself or in principle.
But to the description of the experiments I will add some corol
laries, and some conjectures and hypotheses, primarily with this
purpose, that I may smooth the way for understanding new experi
ments, whereby, if we cannot attain the truth, at least a new ap
proach thereto may be opened. The affair began at first as follows :
Part One
THE EFFECTS OF ARTIFICIAL ELECTRICITY ON
MUSCULAR MOTION
I dissected and prepared a frog, as in Fig. a, Tab. I, and placed it
on a table, on which was an electrical machine, Fig. I, Tab. I, widely
removed from its conductor and separated by no brief interval.
When by chance one of those who were assisting me gently touched
the point of a solgel to the medial nerves, DD, of this frog,
immediately all the muscles of the limbs seemed to be so contracted
that they appeared to have fallen into violent Jgflij; ognvulsipns.
But another of the assistants, who was on hand when I did electrical
experiments, seemed to observe that the same thing occurred when
ever a spark was discharged from the conductor of the machine,
(Fig. i, B).
He, wondering at the novelty of the phenomenon, immediately
apprised me of the same, wrapped in thought though I was and
pondering something entirely different. Hereupon I was fired with
incredible zeal and desire of having the same experience, and of
bringing to light whatever might be concealed in the phenomenon.
Therefore I myself also applied the point of a scalpel to one or other
crural nerve at a time when one or other of those who were present
elicited a spark. The phenomenon always occurred in the same man
ner: violent contraction in individual muscles of the limbs, just as
if the prepared animal had been seized with tetanus, were induced
at the same moment of time in which sparks were discharged.
But fearing lest these very motions arose rather from the contact
of the point, which perchance acted as a stimulus, than from the
spark, I again tested the same nerves in the same way in other frogs,
and even more severely, but without any spark being elicited at
that time by anyone; but no motions were seen at all ^ Hence it oc
curred to me that perhaps for the induction of the phenomenon
both the contact of some body and the passage of a spark were
simultaneously required.fWherefore I applied the edge of the scalpel
again to the nerves and held it motionless, both at the time when a
spark was being elicited and when the machine was perfectly quiet.
But the phenomenon appeared only when the spark was produced.
LUIGI GALVANI
We repeated the experiment, always employing the same scalpel:
but not without our surprise, sometimes, when the spark was pro
duced, the aforesaid motions occurred, sometimes they were lacking.
Aroused by the novelty of the circumstance, we resolved to test
it in various ways, and to experiment, employing nevertheless the
same scalpel, In order that, if possible, we might ascertain the causes
of the unexpected difference; nor did this new labor prove vain; for
we found that the whole thing was to be attributed to the different
part of the scalpel by which we held it with our fingers: for since the
scalpel had a bone handle, when the same handle was held by the
hand, even though a spark was produced, no movements resulted,
but they did ensue, if the fingers touched either the metallic blade
or the iron nails securing the blade of the scalpel.
Now, since dry bones possess a non-conductile, but the metallic
blade and the iron nails a conductile nature, we came into this sus
picion, that perhaps it happened that when we held the bony handle
with our fingers, then all access was cut off from the electric current,
in whatever way it was acting on the frog, but that it was afforded
when we touched the blade or the nails communicating therewith.
Therefore, to place the matter beyond all doubt, instead of a scal
pel we used sometimes a slender glass cylinder H, Fig. a, wiped clean
from all moisture and dust, and sometimes an iron cylinder G. With
the glass cylinder we not merely touched but rubbed the crural
nerves, when the spark was elicited, but with all our effort, the
phenomenon never appeared, though innumerable and violent sparks
were elicited from the conductor of the machine, and at a short dis
tance from the animal; but it appeared when the iron cylinder was
even lightly applied to the same nerves and scanty sparks elicited.
f Hence it appeared to us clearly established, what we had suspected
to be true, that contact of a conducting body with the nerves is also
required in order that the phenomenon should occur| But when both
the body by which the nerves were touched, and the man who
touched them, could be available, we applied the iron cylinder G to
the same nerves, without touching it with our hands, that by this
means it might be determined whether the phenomenon was to be
ascribed to the man and the iron cylinder, or to the latter alone.
When things were thus disposed, no motion of the muscles occurred
when a spark was produced. Therefore, in place of the cylinder, we
employed a very long wire, KK, to see whether in any way that
l6 EFFECTS OF ELECTRICITY ON" MUSCULAR MOTION
PQ
<
H
LUIGI GALVANI 2/
would replace the lack of the man, or not; and again there were con
tractions of the muscles on the passage of the spark.
From these observations it was clear to us that there is required
not only the application of a conducting body to the nerves, but also
a certain magnitude and extension thereof, for the production of the
phenomenon. Hereafter, for the sake of perspicuity, not of brevity,
let us be permitted to call such a conductor a nerve-conductor.
Moreover, we attached to the extremity of this conductor a frog
by means of a small hook fixed into its spinal cord, Fig, a, and some
times placed the frog opposite the machine, sometimes placed its
conductor so that the frog was now near the machine, now far dis
tant from it, and therefore now the feet, now the prepared nerves,
were turned towards the machine, which had the conductor now
before now behind it; nevertheless contractions were always ob
tained equally.
We investigated moreover whether the phenomenon would be
obtained in prepared animals, from a machine situated far distant,
and this employing very long nerve-conductors. Moreover, the trial
was so conducted that when an iron wire, 150 feet long and more,
was employed, nevertheless, when a spark was produced, contrac
tions of the muscles occurred, even at so great a distance from the
machine.
We arranged an experiment in this way. We suspended an iron
wire, EEE, Fig. 3, by a series of silk threads and, as the physicists
say, insulated it. One end we attached similarly by silk threads to a
nail driven in the wall, F; the other we conducted far from the ma
chine the length of the wire into various other rooms. To this, at
point C, we attached another iron wire, B, to whose extremity a
frog was attached; and for convenience enclosed the frog in a glass
jar, A, the bottom of which was filled with some conducting material,
like water, for example, or very fine lead shot, whereby a better
experiment resulted. But when a spark was produced from the con
ductor of the machine, surprisingly the headless frog moved at so
great a distance and jumped vigorously about. The same thing hap
pened if a frog outside the glass jar was attached in the same way to
conductor EE, and far more quickly if there were attached to its
feet some conducting body which communicated with the earth.
Having ascertained the situation in an insulated conductor, we
explored what would happen with one not insulated.
28 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
For this purpose, we attached the same iron wire to various hinges
of doors of chambers of our house, which were six in number, other
things having been prepared as before: smaller contractions, but
some in a prepared frog, appeared, when a spark was elicited.
These observations having been made, I resolved to investigate
also whether the effect of such electricity would act and diffuse itself
in all directions and in a circle. Therefore, having distributed various
nerve-conductors circularly around the conductor of the machine at
no short distance therefrom, and having attached a prepared frog
to every single one of them, and having produced a spark, at one and
the same time, not infrequently, the individual frogs moved, espe
cially when the conducting body, as in the previous experiment, was
attached to the feet of individual frogs, and most strongly when it
was extended as far as the ground which was easily accomplished,
either by a long metal wire attached to the individual feet of frogs,
or if the frogs were grasped with the fingers.
But when we discovered the use and necessity of conducting bodies
attached to the feet, it filled us with the desire to undertake other
experiments concerning this matter; and, when these had been per
formed, it was determined that conducting bodies attached to mus
cles, for the purpose of obtaining contractions, were either sometimes
alone sufficient without nerve conductors, or at least certainly with
no small influence thereon; and the more, the larger they were and
the more they excelled in power of conduction; but most, if they
communicated with the earth; but at least they were as powerful as
those we were accustomed to attach to nerves.
These conductors we will hereafter call muscle-conductors, that
they may be conveniently distinguished from those which we have
called nerve-conductors.
Now, indeed, we saw no contractions ensue when a spark was
produced, even when we attached its conductor to each of the
muscles, if the nerve-conductor, extended far from the machine,
were intercepted by any non-conducting body, as if it were carefully
prepared partly from conductile metal substance, partly from non-
conductile substance, like glass or resin or silk, as if the conductor B,
Fig. 3 were not attached to conductor EE at point C, but were sus
pended in a silk sling D; a new and indubitable demonstration that
electricity flows through such conductors.
But we tested the fact not only by interception but also by total
LUIGI GALVANI 29
interruption of the conductor, and with the extremities of the inter
rupted conductor placed at a minimal distance from one another:
there was no manifestation of any phenomenon at all.
But we endeavored also in some other way to interrupt the free
passage of electricity through the conductor. We placed a prepared
animal on an insulated surface, but did not, as before, connect its
nerve-conductor either with the nerves or with the spinal cord, but
placed it on the same surface in such a way that its extremity was
distant from them several lines, sometimes even an inch; contrac
tions resulted when a spark was elicited, they occurred also in limbs
on the conducting surface when the nerves were placed at the same
distance on an insulated surface or held elevated between the fingers,
whether a short or a long nerve-conductor were employed, and
whether the animal were near to or far from the machine. But they
were completely lacking if the nerves and their conductor, separated
from them as above, lay on a conducting surface.
And we did not fail to investigate whether this, which might be
electricity, freely pervading not the surface merely but the substance
of the conductors, nevertheless would excite the contractions of
which we have often spoken. Therefore we wholly covered and in
vested, except for its extremities, the iron wire which constituted the
nerve conductor with an insulating material, namely common wax,
or sealing wax, or pitch. But, when a spark was produced, contrac
tions occurred, as in the free conductor.
Moreover, these individual facts having been investigated and
confirmed by a long series of experiments, it was possible not only
to ascribe the phenomenon of such contractions to electricity, but
also to note the conditions and as it were certain laws by which it
was governed.
Muscular contractions of this sort, then, seemed to us, within
certain limits, to vary directly with the strength of the spark and of
the animal and especially the extent of the nerve-conductors, but
inversely with the distance from the conductor of the machine.
Likewise these contractions generally appeared to us greater when
the animal was placed on the same table as the machine and the
table was covered with oily pigment, or when the animal, removed
from the table, was laid on an insulating, rather than on a con
ducting, substance.
I have said that it had seemed to me that a direct proportion was
3O EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
preserved in the contractions, but only within certain limits. For
when, for example, a certain extension of the nerve-conductor has
been found which is sufficient to produce the effect, if you diminish
this, the contractions are not diminished but fail; but if you increase
it, the contractions grow stronger, but only until you reach a cer
tain extension, beyond which, however much you extend the nerve-
conductor, they increase barely or not at all: and the same can be
said of other elements of the stated proportion.
But indeed, so great was the observed capacity of the spark de
rived from the conductor of the machine for exciting muscular move
ments, that it seemed to us that much greater contractions were
promised from the electric flame which breaks out when the circuit
is overloaded. But the thing turned out altogether differently; for
not without our amazement, in the animal prepared in the usual
manner no motions ensued.
But now, these experiments having been made in positive elec
tricity, as they say, it seemed to remain for us to make similar tests
also in negative. First, therefore, we insulated the electrical machine
and its operator. He held in his hand an iron cylinder to which we
approximated the frogs provided, as was necessary, with their con
ductors; the frogs were placed on a glass surface, in order that no
neighboring bodies might give them any electricity. Then the opera
tor of the machine, with the iron cylinder which we have mentioned,
industriously elicited sparks from the neighboring objects: we then
saw contractions occur in the prepared frogs, just as they occurred
with sparks elicited from the conductor of the non-insulated machine.
Moreover, we tested negative electricity in another way, which
was as follows. At a certain distance from the negative surface of a
Leyden jar we placed the nerve-conductor C, Fig. 4; then we elicited
sparks Fig. 5 from the charged surface, as the physicists say, or from
that which was endued with positive electricity. The frogs moved
in the same way as when positive electricity was employed; they
moved also when the iron wire, which constituted the nerve con
ductor, was at some distance from the external surface of the jar,
and when it was wholly enclosed in a long glass tube and the frog
itself guarded in a glass jar, if the open end of this tube touched the
aforesaid external surface of the jar. Moreover, the same contrac
tions were obtained, whether the spark was elicited from the crook
of the Leyden jar at the same time when the said jar, as they say,
LUIGI GALVANI 3!
was being charged, or in the same place in which it was charged, or
elsewhere, and far removed from the machine.
These phenomena, moreover, occurred when the frogs were
equipped not only with a nerve-conductor, but merely with a muscle-
conductor: in a word everything was confirmed in this experiment of
the jar, as in the former of the machine, if the prepared animal could
receive no electricity from the external surface of the jar, or from
neighboring bodies, or from any other possible source.
But we wished also in another way to test electric surfaces nega
tively, and by eliciting sparks from them, to investigate such con
tractions; therefore I placed a prepared frog on the upper surface of
the square to which the electricity of the machine was constantly
flowing, and elicited a spark from the inferior surface, both when the
machine was quiet and when it was rotating. Rarely, though some
times, when it was quiet, but then only from quiet of the machine;
but never when rotating, did the customary contractions of the
muscles fail to occur.
These experiments having been made by means of the electric
machine, we also called to the experiment electricity of an electro-
phor, that we might omit no kind of electricity exhibiting a spark.
Therefore we elicited a spark from the shield of an electrophor, and
the customary phenomenon of muscular contractions presented it
self, not at as great distances as when the spark was elicited from the
conductor of a machine, but at very short distances; moreover the
contractions themselves were very slight. Although, indeed, after so
many experiments, there seemed to us scarcely any doubt about the
effects of electricity, and scarcely any about the cause of the phe
nomenon, nevertheless nothing occurred to us more suitable for con
firming the thing more and more than to apply the most delicate
electrometers to animal conductors.
To these, therefore, we adapted a small electrometer constructed
after the manner of the justly celebrated Volta , whose straws, that
they might be more suitable for the experiment we covered on one
side with very thin silver-foil: when the experiment was performed,
when the insulated conductors of the machine were in rotation, the
straws not infrequently were separated one from another, but they
often came together again on the passage of the spark; but when
they were free, not least in rotation of the machine, the straws mu
tually receded one from another, and on extortion of the spark pro-
32. EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
duced little leaps and vibrations which seemed to indicate some
passage of electricity through the conductors of the animal at the
time when contractions are excited at the extortion of a spark.
Now indeed, that the thing might be put beyond ail doubt, we
have striven in various ways to cut off all access for electric fluid of
the machine in any way acting both on the animal and on his con
ductors. First, therefore, 1 enclosed the animal in a glass jar, then
in one with a perforated wall, near which was an electrical machine,
and into this foramen, which pierced the entire thickness of the wall,
I inserted a glass tube so that a nerve-conductor, passing through
the inserted tube, so fitted the orifice of the jar, artificially closed
with glue, that it passed from the opposite surface of the wall and
hung down into the next room. When a spark was elicited from the
conductor of the machine, muscular motions ensued.
Conversely also I placed the animal and his conductor, with the
conductor in the jar where first the animal was, and the animal
where first the conductor hung; then I placed everything in the same
arrangement as before, and elicited a spark, and the same move
ments ensued.
But although by this kind of experiment every pathway for elec
tric fluid of the machine seemed cut off, nevertheless I devised and
constructed a little machine, Fig. 6, which was far simpler and more
convenient than the apparatus hitherto described, and which could
easily be placed at various distances from the (large) machine, and
within which not only the animal, but also both the nerve-conductor
and the muscle-conductor, could easily be enclosed and concealed.
Now the little machine is of this nature. It is compdsed of two
glass jars, of which one rests upon the other. In the upper jar is the
nerve-conductor, which, for the sake of convenience, can be made of
small lead shot, which can serve as muscle-conductor, since the
animal, standing in them with his feet, has them as it were attached
to his muscles.
The animal in this situation both is easily restrained and has
communication with the conductor of the superior jar through his
spinal cord by means of an iron wire which both is attached to the
cork stopper of the same jar, and projects in its cavity, and is sur
rounded and covered with lead shot.
One must beware of this kind of stopper, lest, when the upper
jar is inverted, that it may be superimposed on the other, the lead
LUIGI GALVANI 33
shot fall out; and lest the same jar easily become separated from the
lower, and the electric fluid find a way for itself through the cracks
which may easily remain between the mouths of both jars, their lips
are attached and stuck together by a certain special glue made of
wax and turpentine, firmly but nevertheless so that the jars can be
separated and joined again in accordance with desire and oppor
tunity.
Now when this little machine is placed on the table on which is
the electric machine, at a certain distance from the conductor of the
same, and a spark is produced, movements are seen, not merely the
same but more vigorous than when the animal and his conductors
are exposed to the open air; and the laws, which were indicated
above for the muscular movements were maintained in the given
proportion. These things having been observed, I would readily
have forsaken my first opinion, whereby I considered the electricity
of the conductor of the machine, in whatever way or manner excited
in the extortion of the spark as the active origin and cause of these
muscular movements, unless I had been recalled to the same opinion
both by experiments previously performed and by a rising suspicion
that the phenomenon was chiefly to be ascribed to electricity of the
interior surface of the glass acting on the animal and its conductors
at the time of discharge of the spark; in which suspicion, indeed, I
was wholly confirmed not only by other experiments subsequently
instituted, but also in the first by the movements of the electrom
eter located in the same little machine. For the very light shot and
the wires, of which the electrometer was composed, changed position
immediately when the machine was turned, and were restored again,
when sparks were elicited, into their former position and contact.
Now, indeed, these and other things having been performed and
ascertained, that seemed at last to remain which promised the great
est usefulness in our experiments, that we should institute them also
in living animals.
This therefore we did with the crural nerve, not dissected inside
the abdomen, lest the animals might easily die, but exposed in the
thigh and separated from adjacent structures and drawn outside the
muscles, and the conductor applied to it; contractions ensued on the
passage of the spark in the corresponding leg alone, only less, as it
seemed to us, than in the dead animal.
But since in our individual experiments, hitherto described, the
34 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
animal and the machines and conductor communicated one with
another through the intervening atmosphere, we wished also to ascer
tain what would happen if this communication first were interrupted
and then finally restored.
First I accomplished it as follows: arranged under a glass jar, as
in Fig. 6, 1 placed a little machine along with a prepared animal and
its conductors at a short distance from an electric machine; then I
elicited a spark, and motions occurred according to custom.
I then placed this same jar, along with an enclosed little machine,
under another much larger, and this under another still larger: again,
when a spark was elicited, similar motions ensued, though feebler
the greater the number of recipients and the thickness of their walls.
After this, I cut off all communication of air between the animal
and the electric machine. Namely, I placed the little machine, in
which was the animal, in the receiver of a pneumatic machine, in a
place moderately distant from the conductor of an electric machine;
I perforated the upper jar of the little machine, in order that the air
might be evacuated from it by repeated exhaustions: then, some
times when the air was exhausted, and sometimes when it was not,
I elicited a spark: contractions occurred in each case, nor, as it
seemed, were they appreciably dissimilar.
Now then, electricity acting through a spark having been tested
in such various ways, we investigated with diligence and labor
whether it exercised its control also by other effects and means on
muscular motion. Sometimes it was possible to observe muscular
contractions, if the nerve-conductor, B, Fig. 3, was placed as near
as possible to the conductor of the electric machine, then the shield
of the electrophore raised from the resinous surface, or if the same
shield were transferred close to the same conductor, when the elec
trophore was far distant from the same conductor, without any
spark being elicited.
These experiments were all performed in animals which are called
cold-blooded. These things having been tested and discovered, noth
ing was more in my desires than to perform the same or similar
experiments in warm-blooded animals, as for example in hens and
in sheep. The experiment having been tried, the result was the same
in the latter as in the former. But there was need of a different
preparation in the latter; for it was necessary first to expose the
crural nerve, not inside the abdomen, but externally in the thigh
LUIGI GALVANI 35
itself, and to separate it from other parts and bring it to the surface,
then apply the conductor to it, and then elicit the spark from the
conductor of the machine, with the leg either attached to the living
animal or resected from it as soon as possible; for otherwise, if the
customary manner of preparing frogs were employed, the phenome
non was wholly lacking, perhaps because the power of self-contrac
tion of the muscles was lacking beforehand, which that long and
complex preparation can release.
But indeed, in this kind of experiments, whether in warm or in
cold animals, there are some things at the end, and these peculiar
and, as I think, not unimportant to note, which never presented
themselves to us. One was that prepared animals were more suitable
for these phenomena, the more advanced they were in age, and also
the whiter their muscles were and the more they were deficient in
blood, and therefore perhaps the muscular contractions were
prompter and easier and could be excited much longer in cold than
in warm animals; for the former, in comparison with the latter,
have more dilute blood, more difficult to coagulate, and therefore
flowing much more easily from the muscles : another was that pre
pared animals, in whom these electric experiments were undertaken,
decay and rot much more quickly than those who have suffered no
electric force: finally that even if the phenomena which we have
described thus far as occurring did so in the way we stated, animals
prepared for experiment fail differently. For if the conductors are
applied not to the dissected spinal cord or to the nerves, as we have
been accustomed, but are applied or even attached to the brain or
the muscles, or if nerve conductors are extended or prolonged, or
if nerves according to custom are in the least detached from sur
rounding parts, the contractions are either none or very slight. Many
accepted things certainly, which we have discovered from these
experiments, we refer chiefly to this method of preparing and sepa
rating nerves.
Part Two
THE EFFECTS OF ATMOSPHERIC ELECTRICITY
ON MUSCULAR MOTION
Having discovered the effects of artificial electricity on muscular
contractions which we have thus far explained, there was nothing
we would sooner do than to investigate whether atmospheric elec
tricity^ as it is called, would afford the same phenomena, or not:
whether, for example, by employing the same devices, the passage
of lightning, as of sparks, would excite muscular contractions.
Therefore we erected, in the fresh air, in a lofty part of the house,
a long and suitable conductor, namely an iron wire, and insulated
it, Fig. 7, and to it, when a storm arose in the sky, attached by their
nerves either prepared frogs, or prepared legs of warm animals, as
in Fig. 20, 21, Tab. IV. Also we attached another conductor, namely
another iron wire, to the feet of the same, and this as long as possible,
that it might extend as far as the waters of the well indicated in the
figure. Moreover, the thing went according to our desire, just as in
artificial electricity; for as often as the lightning broke out, at the
same moment of time all the muscles fell into violent and multiple
contractions, so that, just as the splendor and flash of the lightning
are wont, so the muscular motions and contractions of those animals
preceded the thunders, and, as it were, warned of them; nay, indeed,
so great was the concurrence of the phenomena that the contrac
tions occurre<^ both when no muscle conductor was also added, and
when the nerve conductor was not insulated, nay it was even pos
sible to observe them beyond hope and expectation when the con
ductor was placed on lower ground, Fig, 8, particularly if the light
nings either were very great, or burst from clouds nearer the place
of experimentation, or if anyone held the iron wire F in his hands
at the same time when the thunderbolts fell.
Moreover, the phenomenon occurred whether the animal was
exposed in the fresh air, or, for the sake of convenience, had been
enclosed in a suitable jar, as in Fig. 7, or kept within the room. It
occurred also although the nerve-conductor was at some distance
from the nerves themselves, particularly with lightnings either more
violent or nearer, as we said occurred in artificial electricity when
36
LUIGI GALVANI 37
the sparks were either stronger or extorted nearer the animal. Finally
that worthy of notice occurred, that not merely by one contraction
of muscles was the whole thing manifested in the lightning as in the
spark, but by many, succeeding one another as it were in one mutual
moment of time, of which the number of thunders seemed to corre
spond to the number which a thunderbolt is wont to produce.
Now, indeed, such contractions were produced not merely with
lightning but in a stormy sky, with clouds passing over the almost
removed conductors they arose for the most part spontaneously;
and when this had happened, both the electrometers gave no slight
signs of electricity, and not rarely sparks could be elicited from the
conductors raised high in air, differently from when contractions
were obtained with lightning-flashes; for then more often no sparks
were elicited, and more delicate electrometers hardly aroused any
suspicion of electricity.
Now experiments of this kind were undertaken not only in dead
but also in living animals, and in both the phenomenon appeared,
and none of those things was omitted which we have discovered in
artificial electricity, but all for the most part occurred in the same
way. At first sight, indeed, it seemed that this considerable differ
ence existed, that the prepared frogs which, with a suitable conduc
tor, were enclosed in a little glass machine, Fig. 6, Tab. I, separated
from the conductor of the electric machine by an interval, on the
passage of the spark were violently disturbed, as we said, but, when
lightning burst from the clouds, were wholly quiescent; perhaps
either because, if any electricity were conveyed from the electric
cloud to the little machine by means of the conductor, it was very
slight, and occupied a very small part of its surface, so that it was
not adequate for inducing contractions, or perhaps because none
was carried to the same little machine; just as for the most part,
for the same reason the same contractions are lacking on the passage
of the spark, if the little machine is placed, not near the electric
machine, but near that end of the electric conductor, EE Fig. 3,
Tab. I, which is far distant from the same machine.
Upon diligent investigation of the circumstance, on this account,
the manner of action appears similar between artificial and atmos
pheric electricity; perhaps for obtaining these contractions within
the little glass machine, it is necessary that the electric atmosphere,
either wholly or for the most part, should surround the same ma-
38 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
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LUIGI GALVANI 39
chine; but, from what has hitherto been stated, it seems to be far
removed from the position of the little machine and from the ex
periment.
But not merely the phenomenon having been explored, but its
laws also having been subjected to examination, we have ascertained
that the same are maintained in no dissimilar manner in atmos
pheric, as are maintained in artificial, electricity.
Now, indeed, the effects of storm electricity, as they say, having
been investigated, not of thunder and lighting alone, it occurred to
us also to test what sheet lightning and northern lights would pro
duce in animals prepared in the customary way. Therefore we
adapted our animals to an atmospheric conductor not only during
lightning but during northern lights. But no contractions were ever
then produced, perhaps because either such coruscations do not
depend on electricity or, if they do, either in too remote a place,
or they occur for some very different reason than thunderbolts.
But these are questions for the physicists.
Part Three
THE EFFECTS OF ANIMAL ELECTRICITY ON
MUSCULAR MOTION
The effects of stormy atmospheric electricity having been tested,
my heart burned with desire to test also the power of peaceful,
everyday electricity.
Wherefore, since I had sometimes seen prepared frogs placed in
iron gratings which surrounded a certain hanging garden of my
house, equipped also with bronze hooks in their spinal cord, fall into
the customary contractions, not only when the sky was lighting,
but also sometimes when it was quiet and serene, I thought these
contractions derived their origin from the changes which sometimes
occur in atmospheric electricity. Hence, not without hope, I began
diligently to investigate the effects of these changes on these muscu
lar motions in various ways. Wherefore at different hours, and for
many days, I inspected animals, appropriately adjusted therefor;
but there was scarcely any motion in their muscles. Finally, weary
with vain expectation I began to press the bronze hooks, whereby
their spinal cords were fixed, against the iron gratings, to see whether
by this kind of device they excited muscular contractions, and in
various states of the atmosphere, and of electricity whatever variety
and mutation they presented; not infrequently, indeed, I observed
contractions, but bearing no relation to varied state of atmosphere
or of electricity.
Nevertheless, since I had not inspected these contractions except
in the fresh air, for I had not yet experimented in other places, I
was on the point of seeking such contractions from electricity of the
atmosphere, which had crept into the animal and accumulated in
him and gone out rapidly from him in contact of the hook with the
iron grating; for it is easy in experimentation to be deceived, and to
think one has seen and discovered what we desire to see and dis
cover-
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 fixed in his spinal cord, behold the same contractions and
the same motions ! Likewise continuously, I tried using other metals,
4 o
LUIGI GALVANI 4!
in other places, other hours and days; and the same result; except
that the contractions were different in accordance with the diversity
of metals, namely more violent in some, and more sluggish in others.
Then it continually occurred to me to employ for the same experi
ment other bodies, but those which transmit little or no electricity,
glass for example, gum, resin, stone, wood, and those which are dry;
nothing similar occurred, it was not possible to observe any muscu
lar motions or contractions. Results of this sort both brought us no
slight amazement and began to arouse some suspicion about in
herent animal electricity itself. Moreover both were increased by
the circuit of very thin nervous fluid which by chance we observed
to be produced from the nerves to the muscles, when the phenome
non occurred, and which resembled the electric circuit which is
discharged in the Leyden jar.
For, while I myself held in one hand a prepared frog on a hook
fixed in his spinal cord, and manipulated him so that with his feet
he rested on a silver box, with the other hand I touched with some
metal object the surface of the same box on which the frog rested
with his feet, or his sides, and beyond expectation I saw the frog
fall into no slight contractions, and indeed as often as I employed
the same kind of device.
Having made these observations I asked Rialpus, a Spaniard, a
very learned man, formerly a Fellow of the Society of Jesus, who
was then rusticating with me in the villa of the most excellent and
noble gentleman, Jacob Zambeccari, I asked him, I say, that as in
other experiments he was very kindly accustomed, so in this he
would afford me a helpful and assisting hand and hold the frog, as
I myself did formerly, while I myself touched the box again, both
for convenience and in order that I might change a little my mode
of experimentation. But, contrary to expectation, the contractions
failed; I continued the experiment as before, and performed it alone;
and immediately they returned.
This moved me to hold the animal myself with one hand, as be
fore, and with the other the hand of Rialpus and to ask him that he
himself with his other hand should either touch or strike the box in
which the appearance of an electric circuit was produced: imme
diately the same phenomenon of the contractions occurred, not with
out our pleasure and wonder, because it was again lacking, if we
removed our hand, and appeared again if the hand were replaced.
EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
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LUIGI GALVANI 43
But although it seemed that these things could all be demon
strated as an electric extension of the nerve fluid through the human
chain, nevertheless, in order that we might more and more confirm
a thing so great and concealing so much novelty, we wished that
not by the clasp of hands alone but through some intermediate
body, either insulating, like a glass cylinder, or conducting, like a
metal cylinder, Rialpus and \ should constitute the chain; but, the
experiment having been made, we beheld, not without pleasure,
that the phenomenon occurred when a metal cylinder was em
ployed, but failed altogether when glass was employed or when it
was touched in vain or when the box was struck with heavier blows
of the conducting body; so that on this account we considered it as
ascertained that electricity of this sort excites contractions, in what
ever way it may ultimately do this.
But, in order that I might put the thing more in the open, it was
most opportune for me to place the frog on an insulating surface,
namely glass or resin; then to employ either the whole arc or the
conducting arc or in part the non-conducting arc, one end of it
with a hook fixed to the spine; the other end applied either to the
muscles of the leg or to the feet. But when the experiment had been
done, we saw the contractions performed when the conducting arc
was employed, Fig. 9, but fail completely when we used the arc
partly conducting and partly insulating, as in Fig. 10. The conduct
ing arc was of iron wire, but the hook of brass wire.
These things having been observed, it seemed to us that the con
tractions which we have said occurred in frogs placed on a metal
surface when a hook in the spinal cord was pressed towards the same
plane, ought to be repeated by a similar arc whose ends should be
borne in some way by a metallic plane, and hence it should result
that contractions should not be excited in frogs placed on any in
sulating surface, provided the same devices were employed alto
gether.
This opinion of ours, if I judgq correctly, was clearly confirmed
by a not inopportune phenomenon casually observed: for if a frog
is held in the fingers so suspended by one leg that a hook fixed in
the spinal cord touches a silver surface and the other leg freely falls
into the same plane, Fig. 11, Tab. Ill, as soon as this same leg touches
the surface itself immediately the muscles contract, wherefore the
the leg rises and is drawn up, but soon relaxes of its own accord and
44 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
again falls to the surface, and as soon as it comes in contact with it,
is again elevated for the same reason, and so it continues thereafter
to rise and fall alternately, so that, like an electric pendulum, the
same leg seems to imitate the other, not without admiration and
pleasure on the part of the beholder.
It is easy to see how conveniently and aptly this phenomenon
can be repeated, taking turns on the supporting surface with each
arc most fit for the aforesaid circuit, while it calls the free leg to the
same surface, but to the circuit wholly different, at the same time
that the other leg recedes from it. These are neither doubtful nor
obscure signs of the metallic surface bearing alternate arcs.
But it can hardly be said what is the capacity and aptitude of
this surface for exciting muscular contractions, that namely whereby
contractions may be obtained, both great and frequent, sometimes
even constant for a long time, not only if the hook fixed in the spinal
cord is either pressed against the metallic surface itself,, or rubbed
against it, but also at the same time that the hook itself touches the
same surface, and if it afterwards touches it, some of its contacts
with the surface are changed, as if you lightly strike either the sur
face on which the animal is, or the bodies on which the same plane
rests. But concerning the kind of arc which the metallic plane car
ries, so much for the present.
But before our discussion leaves the use and capacities of the arc,
we do not wish to omit this about its capacity and I almost said
necessity for demonstrating this kind of muscular contractions as
conveniently as possible, that the same are obtained, and often,
more clearly and promptly not merely with one but with two arcs
also, disposed and employed in such a way that one extremity of
one arc is applied to muscles, one extremity of the other arc to
nerves, and the two remaining extremities are brought to mutual
contact, or if necessary are touched alternately, Fig. ia. In which
this peculiarity is observed: that electricity of this sort, incuding
contractions, is not to any appreciable degree diffused or dissipated
either by contact of the hands with either arc or by repeated con
tacts of the arcs with parts of the animaL
But that is also peculiar and worthy of notice when the strength,
particularly of prepared animals, languishes, around the arc-con
ductors or conducting surfaces, it befell us very often to observe
that various and multiple metal substances are very effective both
LUIGI GALVANI 45
for obtaining and for increasing muscular contractions, and indeed
far more than one and the same metallic substance. So, for example,
if the whole arc were iron, or the hook iron and the conducting sur
face likewise iron, very often the contractions will either fail or will
be very scanty. But if one of them were iron, for example, and the
other bronze, much more if it were silver (for silver, in comparison
with other metals, seems to us preferable for conducting animal
electricity), contractions will occur continuously and far greater and
far longer. The same thing happens when one surface of an insulat
ing plane is separated in two places, and equally covered with dis
similar metal foil, as for example, if, in one place, you employ tin
foil, in another, brass-foil, contractions will occur as much greater
as possible than if each place were covered, or, as they say, arma-
tured, with one and the same metal, even silver-foil.
But, indeed, this sort of a circuit of nervous fluid, like electric
fire, having been detected, this seemed the twofold consequence,
that both this or a dissimilar, or rather contrary electricity produces
this phenomenon, as it were duplex, either in a Leyden jar or that
electricity in the charged arc through which it discharges its electric
fluid like a circle; for the movement of electricity cannot be held as
a circuit by the demonstrating physicists, except in restoration of
equilibrium, and either solely or chiefly between contrary electrici
ties. Moreover, in one and the same metal there lay concealed those
opposite by nature which seemed contrary to observations: there
fore it remained that each resided in the animal. Nor did I have any
suspicion in experimenting that any kind of electricity could have
been ascribed to animals, I attached the bronze arc covered with
silver leaf to the glass cylinder, which I held in my hands, when I
applied the arc itself to animals; when this precaution was em
ployed, contractions nevertheless occurred.
These experiments having been performed in the fresh air, the
thought entered my mind, what would happen to the electricity of
an animal, if I should submerge the animal himself under water:
this therefore I did, and according to custom applied to him the
extremities of an arc, one with an iron hook to the spinal cord, the
other to the feet: contractions occurred just as in the fresh air.
But this peculiarity presented itself to me in this experiment,
that if either with the same arc or with any other conducting body
I merely touched the hook in the spinal cord of the animal lying
46 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
under the water, immediately contractions occurred; which I my
self referred to the water transmitting the arc in turn. Therefore
I immersed the animal not in water as before, but in oil, to see
whether contractions occurred just as under water, or were wholly
lacking. Then I applied the same conducting body to the hook in
the spinal cord as before; the contractions wholly failed, the oil
being wholly unequal to taking turns with the conducting arc, a
thing which confirmed me not a little in my preconceived opinion.
These things having been ascertained and noted, it seemed to me
that I could best proceed without any delay to find that double and
opposite electricity in the prepared animal itself, and that either
one has its location in muscle, the other in nerve, or both in either,
as the physicists affirm in the Tourmaline Stone. With all zeal,
therefore, I began to seek and investigate this location; and first
what kind of electricity nerves present. Therefore to the spinal cord
of one of the headless frogs, which I had recently prepared in as
large number as possible, having been killed for experiment, I
closely applied a cylinder, now glass, now made of sealing-wax; but
never at first application did muscular movements occur; but they
were observed when another was employed, generally at a distance
of four or more lines, provided the vertebral tube and had been
covered with tin-foil, as we shall say below. In place of the glass
cylinder, we often used the disc of the electric machine, driven by
numerous revolutions, in order that we might ascertain whether the
greater supply of electricity which was collected in the disc would
excite those muscular contractions which the cylinder could not,
but the experiment had the same result; not the slightest motions
occurred in the muscles.
Therefore the nerve-electricity in the experiments will be positive
since the physicists demonstrate that only between opposite elec
tricities can known effects and motions be obtained.
Then we turned our mind to investigating the electricity of mus
cles : therefore we undertook the same experiments in these as in the
former; but it was not possible to observe any movements in the
muscles when either positive or negative electricity was employed.
Therefore we returned again to nerve-electricity, which was con
forming to our experiments; and in exploring the same with sealing-
wax we used the same devices, whereby we were burned while we
tested it with the extortion of a spark. Nearly the same phenomena
LUIGI GALVANI 47
of contractions appeared, except that those were much less which
were produced with sealing-wax, than those with a spark, corre
sponding to the strength of the electricity. The utility of the con
ductors was the same also, and their laws the same, and clearly the
muscular motions appeared in the same way.
But since nothing seemed to be more suitable for discovering so
obscure and difficult a thing, namely the location of each electricity,
than to increase and apply the electricity, I therefore began to medi
tate sedulously concerning the method of accomplishing this, and,
following analogy, this method presented itself first, that I should
cover the nerves in which electricity seemed to prevail, and whose
nature we had ascertained, with some metal foil, preferably of tin,
no less than the physicists are accustomed to accomplish in their
magic square and Ley den jar, Fig. 9, Tab. III.
With a device of this sort, it is amazing how much stronger mus
cular contractions grow, so much, indeed, that even without an arc,
but with a single contact of a body of any nature, either conducting
or even non-conducting, with armatured nerves, contractions ap
peared, provided only that they had been recently prepared and
that their strength was maintained; so that the arc, and the strength
and utility of other devices, proved far greater; that finally contrac
tions became more violent and longer and fairly constant in animals
vigorous before section, even if either the arc is removed or the body
whereby the armatured nerves are touched.
What more? Such was the power and capacity of this device in
increasing and augmenting the strength of this kind of electricity,
that a circuit which barely, and not even barely, appeared when
hooks and an arc were employed, emerged happily and promptly
in a tadpole, not only through two men, but even sometimes through
three and more, constituting, as it were, an electric chain, and mus
cular contractions were excited, especially in summer time, in older
animals with pale muscles, and when a storm threatens in heaven.
Moreover, in prepared animals, if the denuded cerebrum and de
nuded spinal cord are covered in some part with the same metal
foil, when the arc was employed according to custom, contractions
both vigorous and prompt then began to appear, which, however,
without this kind of device, I had previously striven in vain to ex
cite with the arc or in any other way.
Moreover, the effect of tin-foil applied to nerves having been
48 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
found so great in augmenting animal electricity, I decided to try
also what the same foil would do in muscles; but contractions were
not seen to assume much increase, nay even, when the thing was
tested more often, we finally noticed this, that some increase of con
tractions occurred if only with these parts, the muscles also were
covered with the same layer of tin, and the arc applied to the arma-
tured places.
Not only were the contractions extended by metal foil applied to
the denuded spinal cord, but also by having the vertebral column
covered with the same, applied not only externally in the back to
its muscles, but internally in the abdomen, and especially in the
region where the nerves emerge. And it did not matter if at first you
had covered those parts and the nerves with much foil or with little,
for it was sufficient if you should cover it with any, and should apply
one extremity of the arc to it and the other to the muscles. But in
place of the metal foil we employed with equal utility an electric
amalgam, or sprinkled the nerve with its powder, or applied to the
nerve a pastille made of the same powder with oil. But if we used
any other metallic powder, iron, for example, or brass, even in the
same way, there was scarcely any increase of muscular motions.
Now, indeed, having found the reason why this sort of electricity
assumed so much increase, we then sought its location with more
eagerness and confidence. Hence now a nerve, now a muscle being
covered with the same foil, we drew out from the animal first the
muscle with the corresponding nerve and placed it on an insulating
surface, and applied an arc to it according to custom; we likewise
did the same both in an intact muscle, and in a divided muscle,
namely we enclosed one part of it in metal foil, then applied one
extremity of an arc to the armatured part of the muscle, the other
extremity to the bare muscle; but barely, and not even barely, were
we permitted by these attempts to arrive at any of those things
which we were seeking.
This only we noticed: in the muscle with its nerve brought out
side the animal, far fewer contractions took place than if they had
remained in their natural positions; moreover, in the intact muscle,
though they were scanty hitherto, that they became much slighter,
nay, hardly occurred at all; but nevertheless not rarely some, if one
extremity of an arc were applied to an armatured place on a muscle,
the other to an adjacent and bare surface of the same muscle; but
LUIGI GALVANI 49
when the experiment was tried otherwise, none occurred: also that
it likewise happened, but with much more difficulty, in the internal
substance of a muscle; but that contractions arise far more easily and
promptly if the arc were applied in the same way to an armatured
nerve; nay, if the small extremity of an arc, in place of any other
conducting body, were called into use, and partly an edge of metal
foil and partly a bare nerve were touched by it.
These tests we made concerning the investigated location of ani
mal electricity, by which it is established that the fact, which could
not be sufficiently illustrated by experiments, must be largely com
mitted to conjecture.
Now let us pursue some matters which, as we diligently investi
gated this kind of electricity, presented themselves to us as worthy
of attention; among which this was foremost: that that excited by
common electricity always acts, as we have warned, at a distance of
several lines, but by itself alone not even at the shortest distance,
but always requires actual contact in order that it may exercise its
effect. But we see that greater contractions can often be obtained
more certainly and promptly, if the extremity of the arc is applied
to the very edge of a metallic layer covering nerves or muscles, than
if to the flat surface thereof; likewise if to the extremity of a hook
than if to the other parts thereof: whereby it appears that animal
electricity does not exactly imitate common, ordinary electricity,
whose peculiar nature it is to choose and follow angles and points.
These facts, so obvious and clear, to my judgment, about elec
tricity in muscles and nerves, gave us additional courage that we
should more studiously investigate more and more data about the
same. Hence first, in place of the aforesaid metal foil, we covered
both nerves and muscles in some part with insulating material,
namely silk-web, oil in which pitch was dissolved and wholly im
bued, to see whether contractions would be wholly lacking, when
the arc was employed, or not: they failed completely. But it was
necessary to employ the silk web, and to prepare it in such a way
that it was adequate to insulate contractions, because easily, in the
conducting animals, it became imbued and moistened with lymph,
and not oil alone, because it so yielded place to the extremity of the
arc that it came into altogether absolute contact with the under
lying part.
Then we investigated whether this kind of electricity followed the
5O EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
theory and nature of common electricity in this, that it made itself
an easier way through certain conducting bodies, and through others
a more difficult one.
But we see it follows almost exactly; and first, as the former, so
the latter makes its way more happily through metals than through
wood, but among metals most happily through gold and silver,
more feebly through lead and iron, particularly if the latter is cor
roded with rust, so that if either an arc, or surfaces substituting for
an arc, were plated, and particularly with silver, or, which is more
convenient, covered with very thin silver-foil, the phenomena of
contractions would appear both far more clearly and far more
promptly than if the same had been constructed either of lead, for
example, or even of iron.
But having investigated the power of conduction in solid bodies,
we also explored the same in fluids, and the thing came out the same
way; namely we found that this kind of electricity makes its way
very readily through aqueous fluids, but is wholly blocked and re
tarded by oily fluids. In order that we might investigate this, we
used small glass tubes, which we closed at one end with some mate
rial through which we passed a metal wire, namely silver or brass,
and passed it so covered with tin-foil that by one part it would be
free inside the cavity of the tube, and by the other would be pro
longed far from it; but the tubes we filled with material suitable for
the experiment, namely sometimes aqueous, sometimes oily, and by
a similar device closed them at the other extremity, and equipped
them in the same way with a similar metallic wire. Things being
thus arranged, we used tubes of this sort so that they constituted
either a whole arc, by bending the metallic wires, or part of an arc
whose extremities, according to custom, were applied to an animal.
When these tubes were employed, Fig. 14 Tab. Ill, no contractions
occurred when they had been filled with oil, but only when they had
been filled with water.
Now, nothing seemed to conduce more to deriving utility from
these experiments than to investigate diligently also the faculty of
insulation or of conduction in different parts of animals. The ex
periment having been made we have ascertained that all parts of
dissected animals freely conduct and transmit conveniently this
kind of electricity, perhaps on account of the moisture by which
they are washed, either by nature or in sections and preparations;
LUIGI GALVANI 5!
for if various and recently dissected parts, such as muscle fibers,
cartilages, nerves, bones, membranes; or fluids, as blood, lymph,
serum, urine, received on a glass plate, or enclosed in the aforesaid
tubes, are applied to preparations, and especially to armatured
nerves, and then to the same parts one end of an arc is adjusted,
and muscles are touched by the other, then contractions as surely
occur as if the same arc-end had been applied to the nerves them
selves. Moreover, we ascertained that the same thing happens if
things are arranged as it were in the opposite way, and the experi
ment undertaken with the aforesaid parts, not nerves but muscles
being fitted, but with one extremity of the arc adjusted to the same
parts, and the other to the armatured nerves. But we see the thing
is otherwise, particularly if those solid parts have not recently been
dissected, but are dry by nature or by art. And indeed the phe
nomenon does not appear solely in those parts artificially arranged,
but also in the same either located hitherto by nature in the animal,
or by reason certainly deviating little from the natural; for if one
extremity of an arc is applied to insulated nerves, particularly arma
tured, and the other touches any other part of the body, intactly
and naturally constituted, which ultimately responds to muscles
supplied by the same nerves, the phenomenon almost always oc
curs, just as if the same extremity of the arc were applied to the
muscles themselves; but not without some surprise we saw the same
thing occur, both with nerves and with muscles first cut and sepa
rated from the circuit, then joined again in some artificial way. For
if frogs are prepared in the customary way, and their vertebral col
umn covered with tin-foil and their limbs divided with a knife so
that each limb remains joined only to its own corresponding nerve,
and then one limb removed far from the other, Fig. 15, Tab. Ill,
then one extremity of an arc applied to the same vertebral column,
the other to muscles, or only to the foot of one leg, then only the
muscles of the same leg will move and contract.
But if the same limbs are carefully joined again so that they come
into mutual contact, and the arc applied in the same way and to the
same leg, then all the muscles of each leg will move and contract.
Moreover exactly the same thing happens when the vertebral col
umn is split, with the spinal cord along its axis, and then the parts
of the divided column spread apart with their corresponding nerves,
but the limbs joined as they are by nature; the muscles of only one
52 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
limb fall into contractions when one extremity of an arc is applied
to only one of the aforesaid parts of the vertebral column, the other
to the corresponding leg; but the muscles of each leg fall into con
tractions when the parts of the divided spinal cord are again joined
artificially, and the arc applied by one of its extremities to either
limb, and the other to the same conjoined parts: finally exactly the
same phenomena occur either with the intact trunk of a prepared
animal, or with the trunk divided through the middle sagitally from
top to bottom, provided the divided parts are artificially and care
fully joined and brought into mutual contact, Fig, 16, Tab. III.
It does not seem that these phenomena can be sufficiently fitly
explained except by the interposed moisture of the parts affording
access and passage to the outflowing animal electricity. Will they
be able to throw any light on the hitherto obscure cause and reason
for the cooperation of nerves? Would that wiser physiologists would
investigate this sometime! But perhaps nothing is more suitable for
demonstrating powers of cooperation than if the crural nerves are
prepared according to custom, and the spinal cord and head remain
intact, and the upper limbs intact in nature and position.
For then, if either the crural nerve or the vertebral column is
armatured, and the arc applied partly to the armatured part of the
crural nerve and partly to the corresponding limb, not only the lower
limbs contract, but the upper ones move also, the eyelids move, and
other parts of the head move, so that on this account, the electric
fluid, aroused by nervous contact of the arc, for the most part flows
from the indicated place of the nerves to the muscles, but partly
also through the nerves seeks the higher regions and is carried as
far as the brain, and seems to carry such effect into it that thence,
for whatever reason, motions of other muscles are excited.
But truly, although it would hardly seem permissible to doubt
about animal electricity, confirmed both by experiments and by
factors of analogy and reason, or about its presence and motion in
nerves and in muscles, or about its exit either from the former, or
from the latter, or from both, and about its free excursion through
applied conducting bodies; and although we realize that fortune
and industry have granted us no small fruit of our experiments, in
that to us first perhaps they have revealed whereby to place the
said electricity clearly before the eyes and to derive it from the ani
mal and, as it were, to handle it with our hands; nevertheless, to
LUIGI GALVANI 53
confess the truth, the thing is not yet completely demonstrated and
absolute in all respects, nor does it seem to us to have passed suffi
ciently out of the realm of opinion, unless we might be permitted
also to ascertain the mode and reason, way and manner, whereby
the same phenomena of contractions might be obtained without
either nerves or muscles being touched in any way or by any sub
stance.
We feared lest perhaps these phenomena might in some way be
ascribed to some mechanical irritation either of the arc or other in
struments, and that therefore it was not sufficiently established by
these experiments themselves concerning the very tenuous electric
fluid flowing out through nerves and inducing muscular contrac
tions. Moreover, it occurred to me to try whether, with the nerves
attached to one surface of the magic square, as the upper for exam
ple, and the muscles to the lower, Fig. 20, or the opposite, as in
Fig. 13, and with one extremity of the arc applied to the former,
the other to the latter, surface, in a place far removed from the dis
placed parts of the animal, contractions would occur or not. For by
this sort of experiment I easily learned whether the fluid flowing
out along the nerves had been electrical and the contractions had
originated and started from its passage from the nerves to the mus
cles, whether it was the same as if I had applied the arc to muscles
and nerves without its being possible for any suspicion to arise about
mechanical stimulus being applied to them. But, the experiment
having been made, we saw, not without some delight, that contrac
tions occurred, without occurring by the same method, if glass or
resinous surfaces armatured after the fashion of the physicists had
been placed in one and the same plane, provided they had been
separated by some distance from one another, so that the nerves
were in one of those surfaces, the muscles in the other, and there
had been no communication between them through an intermediate
conducting body, Fig. 18. Moreover we observed that by this de
vice contractions occurred without either nerves or muscles having
been covered with metal foil in the customary method; and we
finally noticed that they occurred if, for example, the spinal cord or
the nerves were placed under water in one jar, the feet in another,
and then, according to custom, the arc applied by its extremities to
both surfaces of water, Fig. 19.
This moreover, furnished us occasion to investigate what would
54
EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
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LUIGI GALVANI $$
happen, if the muscles were placed on an armatured glass surface,
the spinal cord in its own tube and joined to its nerves on a con
ducting surface, either connected by a hook or else armatured ac
cording to custom; what then would happen, if the experiment were
otherwise arranged, namely with the spinal cord placed on the glass
plate, conducting to the muscles, and the arc, as in the preceding
experiment, applied to two opposite places, of which one should
look towards the spinal cord, the other towards the muscles; what,
finally, if both the cord and the muscles should be laid out on one
and the same armatured surface. Truly the contractions were more
languid, and were excited with more difficulty, when the muscles
lay on the glass surface and the spinal cord on the conducting plate;
but on the contrary they became more violent when the spinal cord
was placed on the glass plate and the muscles on the conducting
plate; but sometimes of their own accord they became far more
vehement and longer, appearing without any use of the arc, and as
if recurring, if both muscles and nerves had lain on the same arma
tured glass surface, especially if either light percussion or motion
had been made on the armatured glass surface, so that those trunks
of animals were seen to have fallen into the severest spasticity.
But if anyone compares these phenomena with those which we
said occurred at first, when namely the muscles and the spinal cord
were located on one and the same conducting plate, and contrac
tions were excited either by pressure of a hook against the same
plate or by other indicated means, he will easily understand that
these were then far less than when similar ones were produced on
an armatured glass surface: truly no trifling argument that animal
electricity is dissipated less by conducting bodies than is common,
ordinary electricity; nevertheless that it is dissipated, and that it
is restrained and accumulated by insulating bodies no less than the
former, which, if I judge correctly, will appear far more clearly in
the subsequent experiments.
For before removing my hand and solicitude from these experi
ments, I wished to investigate whether the same phenomena of con
tractions would occur not only on glass or resinous but also on mar
ble or highly polished surfaces, that I might forsooth remove that
doubt which was often observed in my mind, whether the contrac
tions, which I myself used to repeat with animal electricity, pro
ceeded rather from the electricity of an armatured glass or resinous
56 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
surface. Therefore the same experiments were undertaken with ar-
matured marble surfaces as with glass and resinous, and all turned
out the same way, but more languid contractions occurred, so that
those devices had to be employed whereby the effects of animal elec
tricity exciting contractions are augmented. Hence it was often
necessary to equip one surface of one marble plate, or part of it,
(for it is the same, whether you employ two plates, or one divided
into parts by means of armatures), with one metal, tin for example
or silver, and the other with bronze or gold-leaf, in order that con
tractions might occur; perhaps because animal electricity, like com
mon and ordinary, is wont to be checked less readily by marble than
by vitreous or resinous substances.
But this ought not to be passed over in silence, because if the arc
should have one extremity of insulating material, and then that
should be applied, as above, to the armatured plates, it excites no
contractions at all; but they are excited, if either the same extrem
ity, or other insulating body, be applied to armatured nerves, or to
the spinal cord, as we have already suggested.
But having observed the phenomenon in dead frogs and in dis
sected nerves, we were impelled to try the same in living frogs also,
both with intact and with dissected nerves. Therefore, the integu
ment having been reflected and the crural nerve exposed and arma
tured, where it advances completely bare, namely below the place
of the leg which can be compared to the ham, we applied the arc
as usual both to the same nerve and to the muscles of the leg;
contractions occurred not infrequently; but they always occurred
when the nerve was dissected and armatured and laid on an arma
tured glass surface, and then the arc applied either to the nerve,
or only to the same surface, and to the muscles, in the same way as
before; but contractions were lacking, wholly or in great part, if
the plate on which the nerve lay was conductile and had been
insulated in no way: so that it seemed thence to be established that
the mode of action of animal electricity is exactly the same both in
living and in dead animals.
Having had so many, and I think not obscure, indications of the
effects of animal electricity, I wished to find out whether, as we
noted to occur in ordinary and extrinsic electricity, the customary
preparation of nerves and their diligent separation from other parts
contributed anything to collecting and manifesting its powers.
LUIGI GALVANI 5/
Moreover I found that it contributes a great deal. For if with only
the cranium or the vertebral column opened, and the rest of the
animal intact, the cerebrum or the spinal cord was covered with
its own tinfoil, and then one extremity of an arc was applied to an
armatured portion and the other to a leg, some contractions oc
curred in the upper limbs, but none or scarcely any in the lower;
but imperceptibly and gradually others appeared, according as the
animal was denuded and exenterated, and nerves were more and
more separated from adjacent parts, until finally, when all the
nerves were isolated and free and surrounded only with bronze-foil,
they appeared great and violent, with the same arc and the same
method employed, so that it seemed established thence that per
chance paths and some access lie open for animal electricity from
the nerves to the contiguous parts either through moisture or
through lymphatic or blood-vessels accompanying the nerves; and
when these are dissected, the nerves are free, and while they remain
insulated, electricity prepared for motion, flowing to the armatured
place, either wholly or in great part, and completing its circuit
through muscles and nerves by means of the arc, produces the con
tractions far greater than before their preparation.
But that a new phenomenon of this sort exists seems no slight
argument for animal electricity: and perhaps some suspicion may
arise thence that the acceleration of blood and circulation of humors
in the muscular motion depend either principally or in some part
on electricity itself, flowing from the nerves to the vessels and
making inroad into their humors: and surely, if there were room
for this conjecture, perhaps some explanation might emerge thence
why in old men, in whom many vessels coalesce, i.e. become oc
cluded from arteriosclerosis, the electricity, hastening more abun
dantly along the nerves directly to the cerebrum, not infrequently
injures the latter seriously, and for this reason also renders old age
more susceptible to both paralysis, and apoplexy, and other dis
eases of this sort. But of these we will speak elsewhere.
But nothing seemed to us to conduce more to deriving some util
ity from our experiments than diligently to transfer to warm
blooded animals also those which had hitherto been tried in the
cold-blooded.
For I readily realized, if those things which I had discovered had
pertained only to cold-blooded animals, that I had discovered only
58 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
certain of their properties, perhaps hardly associated with any util
ity: but if the same things could be found also in the warm-blooded,
I was shown great hope that the result would be that I might ac
complish not a little towards a little more revealing, if not clearly
explaining, the essence and nature of muscular and nervous powers;
which perhaps without some increase could not be of utility both
to physiology and to medicine.
Moreover, the experiments having been performed, in birds and
in quadrupeds, not once but again and again, not only the principal
phenomena appeared, according to desire, as in cold-blooded ani
mals, namely frogs and turtles, but they both appeared more easily
and were far more conspicuous. It was possible also to observe this
peculiarity in both the living and the dead animal, Figs. 20 and ai,
for example that in a lamb or a chick, with a crural nerve dissected
and covered with metal foil and extended on an armatured glass
surface, contractions were obtained without the device of an arc,
but solely by the contact of some conducting body with the same
surface; but they are never obtained when the nerve is extended on
a metallic surface, unless an arc is applied to the animal according
to custom.
What more fitting, what more certain, than that it should be
demonstrated that animal electricity is diffused to contiguous bodies
by the nerves, and, not otherwise than common and ordinary elec
tricity, is accustomed to be arrested by insulating and dispersed by
conducting substances? These are the things which we have ascer
tained by experiment.
But finally we wish the reader warned that animal electricity,
discovered by us, just as in many other properties, so chiefly in its
inconstancy, variety, and as it were renewal after a certain time,
corresponds not a little with common electricity. For the contrac
tions differ greatly, particularly those occurring in this last part of
the experiments, not only in accordance with the different kind of
animals, but in accordance with the varied nature, age, condition,
and strength of each of them; so that in some they occur very strong
and promptly, feebly in others, and hardly perceptible: they differ
likewise in accordance with varied seasons of the year, and even with
the condition of the sky itself.
For in summer time and with a sky threatening thunder and light
ning, the contractions are accustomed to be stronger and prompter,
LUIGI GALVANI 59
than in winter and with a calm sky, although then we have observed
that the force with which they are excited in the animal is extin
guished more quickly; they are stronger likewise and prompter in
the older than in the younger; in the more active than in the more
sluggish animal; finally in the exsanguinated and pale than in those
filled with blood, and with red muscles.
Moreover, in one and the same prepared animal, there are con
tractions now scanty, now strong, sometimes even none; and some
times they occur at initial experiments; sometimes after many trials*
Moreover this so great variety of effects or contractions occurs not
only at great but also at brief intervals of time*
Finally, diminished after a certain time and certain respite, con
tractions augment, sometimes as if voluntarily, and grow stronger,
nay failing they are also restored as if voluntarily, when other ex
ternal causes and associated phenomena are barely or not even
barely changed, as it appears, not otherwise than as the electricity
seems to be refreshed and restored through rest and quiet at a cer
tain time in the magic quadrant or Leyden jar, dissipated by re
peated experiments.
But that those who have devoted themselves to this kind of ex
periments may the better recognize the use and utility of the arc,
it aids to note this, that with failing contractions which, especially
with armatured nerves, are sometimes excited at the outset by the
sole contact of any conducting body, if then they have recourse to
the use of the arc, they will see the contractions restored anew; but
if they wish to adapt the same arc to the armatured surfaces of a
plane, then let them call it into use either continuously or a little
after the preparation of the animaL
Moreover, we give this advice with this purpose, lest anyone, in
repeating these experiments of ours, in estimating the force of con
tractions and of electricity, should either deceive himself or think
that we have been deceived; for if these same experiments are tried
many times, he will find out many times also the phenomena which
we have produced by trial and experience.
Part Four
CONJECTURES AND SOME CONCLUSIONS
From what is known and explored thus far, I think it is sufficiently
established that there is electricity in animals, which, with Bar-
tholinus and others, we may be permitted to call by the general
name of animal electricity. This, if not in all, yet is contained in
most parts of animals; but manifests itself most conspicuously in
muscles and nerves. The peculiar and not previously recognized
nature of this seems to be that it flows from muscles to nerves, or
rather from the latter to the former, and that it traverses there
either an arc or a series of men or any other conducting bodies which
lead from nerves to muscles by a shorter and quicker way, and flows
most speedily through them from the former to the latter.
From this, moreover, two consequences seem chiefly to ensue,
namely, that the electricity in these parts is, one positive, as we may
believe, the other negative, and that one is wholly distinct in nature
from the other; for when equilibrium is established, there is no
motion, no excursion of electricity, no phenomenon of muscular
contraction.
But forsooth, it is difficult to define in which of the designated
parts one electricity resides, in which the other; whether, for exam
ple, one in muscle, the other in nerve, or both in one and the same
muscle, and from which part it flows. In this obscurity of things,
however, if it is permissible to have an opinion, my mind inclines
towards placing the location of both kinds of electricity in muscle.
For to obtain muscular contractions grant that it is generally
necessary to apply one extremity of the arc outside of muscles, the
other to muscles, as we have said; but it does not seem to follow
thence, because nerves are rich in intrinsic electricity, that there
fore one kind has its seat in them and the other in muscles; just as
in a Leyden jar, although it is customary that one extremity of the
arc should be applied to the external surface thereof, the other to
its conductor, in order that the excursion of electricity may be made
from one to the other, nevertheless it cannot be inferred therefrom
that the electricity which is produced in the conductor is peculiar,
and unlike that which collects within the bottom of the jar; nay
60
LUIGI GALVANI 6l
even it is established that that looks altogether towards the internal
and charged surface, and that both electricities, although contrary,
are contained in the same flask.
Wherefore, if the great number of contractions obtained
in the prepared animal be considered, for which surely the small
quantity of electricity contained in the small part of the nerve
remaining in the prepared muscles is adequate; if, moreover, the
many arguments be considered which are sought from the animal
functions, which openly declare that the nerve fluid, already demon
strated by us is electric and flows freely and swiftly through the
nerves; if finally the obvious and simple explanation of the phe
nomena from each electricity be sought residing in the muscle itself:
it will not seem beside the point, as we shall show hereafter, that
the muscle should be the proper seat of the electricity investigated
by us, but that the nerve performs the function of a conductor.
These things being admitted, it would perhaps be a not inept
hypothesis and conjecture, nor altogether deviating from the truth,
which should compare a muscle fibre to a small Leyden jar, or other
similar electric body, charged with two opposite kinds of electricity;
but should liken the nerve to the conductor, and therefore compare
the whole muscle with an assemblage of Leyden jars. Moreover
that a double and opposite electricity can occupy one and the same
muscle he will readily grant not contrary to the truth who has con
sidered that a muscular fibre, although at first sight very simple,
nevertheless is composed of diverse solid and liquid parts, which
produce in it no slight variety of substance: certainly the sensation
which is present at every point of the fibre warns us clearly that
nerve substance is found in it altogether different from muscle. And
indeed, although, at whatever point of the fibre, this nerve sub
stance neither constitutes the nerve, nor is obvious to the eyes, but
is diagnosed by sensation alone, what prevents us from conjecturing
that it is in some part different from the substance of visible nerve,
or disposed in a different way, and that therefore it has an electrical
nature; but that it is extended as a conducting nerve beyond the
muscle fibre? But perhaps this will appear more clearly from that
which we shall say a little later about nerves,
But much less easily could he deny double electricity in one and
the same muscular fibre who should see that it is neither difficult
nor without some sort of truth that the same fibre should have
62 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
external and internal surfaces opposite one another, either having
observed a cavity, which some assign to it, or from diversity of sub
stances, of which we have said it is composed, which cannot be with
out various holes and surfaces of the muscular substance.
Finally, if anyone turns his mind even for a short time to the tour
maline stone, in which recent discoveries seem to suggest that a
double and opposite electricity is found, he will perceive a new rea
son derived from analogy, whereby a hypothesis of this sort is ren
dered not altogether vain. But, however the circumstance is, we
have seemed to observe so much agreement of causes and of phe
nomena between the eruption of electric fluid from a Leyden jar
and our contractions, that from this hypothesis and comparison we
have barely and not even barely been able to withdraw our mind
and restrain ourselves from deriving both the former and the latter
from a similar cause.
For particularly by employing three devices, electricity breaks
from the internal surface of a Leyden jar; namely by the contact
of its conductor with some highly conductile body, by the apposi
tion of an arc, and by the production of a spark from the conductor
of an electric machine, as we have most recently observed.
Moreover, with these three devices we have already seen con
tractions of muscles obtained: namely by contact of an armatured
nerve which we have made a muscle conductor; by the application
of an arc by its extremities both to the same nerve, and to the
muscle; and finally by the passage of a spark.
But just as among those devices, more apt and stronger than all
for promoting the eruption of electricity from a Leyden jar is the
arc, so we have already seen that it is more suitable than all for
exciting muscular contractions: likewise, just as, unless the conduc
tor projects beyond the orifice of the jar, and especially extends
beyond that on which rests and in which is contained the conducting
material inside the jar, the use of the arc can do hardly anything
to induce these muscular contractions, if the nerves were resected
close to the muscles ; as we have already demonstrated.
But now with respect to the production of a spark, the similarity
proceeds even farther than we have hitherto explained; but in order
that it may be rightly understood, we have noticed that, when by
chance it was made dark, we have observed a luminous pencil to
gleam continuously from the pointed conductor of a charged Leyden
LUIGI GALVANI 63
jar and then after some time to fail spontaneously. But after it
failed, if the jar were placed at a certain distance from the conductor
of the machine and a spark elicited from the same conductor, again
the same pencil appeared at the very moment of time when the
spark was produced, but soon vanished, and so the produced spark
alternately arises and is extinguished. It is a pencil of this sort
which, tested and investigated by us in various ways presented a
new and not inconsiderable argument for the analogy already pro
posed.
For as a pencil of this sort appears at the passage of a spark,
contractions are excited, as we suggested; moreover, just as if a
conducting body, especially one communicating with the earth, be
applied to the external surface of the jar just at the time when the
same pencil either fails or languishes at the passage of the spark,
the spark, again elicited, continuously revives and is restored; so,
if the same conducting body be applied to muscles, we have already
suggested that the contractions of muscles were either restored when
failing or augmented when languishing, while sparks were being
elicited. Likewise, in order that that pencil may appear, when a
spark is produced, whether the conductor faced the machine of the
jar or were in the opposite region; so then, as we have said, contrac
tions occur, whether the nerves and their conductors were from the
region of the machine, or in the opposite direction. But when the
tube is either glass or resinous, if that part of the conductor be oc
cluded, which projects beyond the orifice of the jar, the pencil fails
at the passage of the spark, not otherwise than as contractions fail
when nerves are enclosed in the same tube, although the rest of the
animal is freely exposed to the air.
Moreover, just as, if the jar is placed inside another glass vessel
covered externally with metallic foil, a failing pencil is restored and
revived, when languishing, by sole contact of the exterior of this
vessel, while a spark is being elicited; so if the jar, in which is the
animal, be placed within the same vessel, as in Fig. 3, Tab. I, con
tractions languishing, at the passage of a spark, revive by contact
of the same vessel; and if they cease, they arise again.
But as all appearance of that electric pencil vanishes at the pas
sage of a spark, either if the conductor of the internal surface does
not project, or even if it does, if another conductor is added to it,
and this is extended as far as to the external surface of the jar; so,
64 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
as we have stated, contractions cease on the passage of a spark, if
either the nerve does not project beyond the muscles corresponding
to it, and the contiguous parts, or if it does project, if another con
ductor be applied thereto, which is directed as far as to the muscles
or to their conductors.
But indeed, although this hypothesis and comparison present no
slight appearance of truth, nevertheless there are some things which
seem not slightly to oppose them. For either nerves are of an insula-
tive nature, as some surmise, and cannot then perform the function
of conductors ; or they are conductive: and how then could it be that
the electric fluid should be contained within them and not be per
mitted to escape and diffuse to neighboring parts, not without great
detriment surely of muscular contractions?
But this inconvenience and difficulty will easily be met by him
who imagines the nerves so constituted that they are hollow within,
or composed of some material suitable for conveying electric fluid,
but externally they are either oily or are fused with some other sub
stance which prevents the effusion and dissipation of the said elec
tric fluid running through them. Such a structure indeed, and that
composition of the nerves, will bring it about that they can perform
both functions, namely of conducting the neuro-electric fluid and
at the same time of avoiding the effusion thereof, and will be ad
mirably accommodated both for the animal economy and for ex
periments; if indeed the animal economy seems always to demand
animal spirits forced within the nerves; but experiments demon
strate that the nerves consist chiefly of oily substance.
For not only a large amount of oil is obtained by distillation from
nerves, and far greater than from muscles, but as a greater quantity
of inflammable gas was produced from them by us by a newer
method than it was ever possible to elicit from any other part of the
animal, and this gas was of such a nature that, when ignited, it
emitted a more vivid, purer, and long-lasting flame than the inflam
mable gas derived from other parts is wont; surely this is no slight
indication of more abundant oily substance in nerves.
Nor indeed will this non-conducting substance in nerves, which
seems to be a safeguard lest the electric nerve fluid should be dis
persed, not without severe detriment, be an impediment lest the
same fluid, running out through the intimate conducting substance
of nerves, when there is need, should go out from the same nerves,
LUIGI GALVANI 65
for the accomplishment of contractions, and should be transferred
very swiftly through the arc to the muscles according to its custom
and nature.
For just as, although the conductor of a Leyden jar is covered
with wax, nevertheless, if an arc is applied to it, an explosion is ob
tained, if either the layer of wax were thin, or, though thicker, were
yet covered with a thin metallic foil, provided it does not pass cer
tain limits of thickness, as we have often found; so, from a nerve
made in the same way by nature and armatured by art, electric
fluid can escape and produce contractions.
Let us therefore be permitted to follow a not improbable hypothe
sis of this sort, which however we will immediately discard, as soon
as either learned men dissent from it, or the discoveries of physi
cists or new experiments undertaken in respect to it have demon
strated another more suitable.
Now a few things about the nature of animal electricity chosen
from those which it is permissible to infer from the described experi
ments. This electricity, then, has some things in common with arti
ficial and with ordinary electricity, some things with that of the
torpedo and other animals of this class.
Things in common with ordinary electricity are: First, free and
easy passage through the same bodies through which common elec
tricity is accustomed to pass, namely through metals, among the
foremost, and, among these, through the more perfect and nobler,
such as gold and silver, then through the less noble, namely copper,
iron, tin and lead, moreover through the imperfect metals, such as
antimony, and finally through minerals; likewise free and easy pas
sage through water and moist bodies; more difficult passage through
stones, earth, and wood; finally, interrupted and completely cut off
through glass, resin, and oily substances: wherefrom it results that
if metals are laid on an insulating plane, it is inevitable that common
and artificial electricity $hould accumulate in them, and they would
be wont to produce far greater effects, namely to excite more violent
and longer contractions, than if the same metals communicated
freely with other conducting bodies.
Second, the choice, in excursion, of a shorter and quicker way, an
arc, for example, or angles, or points.
Third, a double and opposite nature, namely one positive, the
other negative.
66 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
Fourth, daily and hourly constant attachment to muscles not
otherwise than common electricity is wont by nature to electric
bodies.
Fifth, spontaneous restoration, not lasting a short space of time.
Sixth, distinct increase of power by employment of the device of
a so-called armature made of the same metal with which the physi
cists are accustomed to surround resinous and vitreous bodies.
Properties in common with electricity of the torpedo and other
animals of this class are chiefly these:
Namely, as it were, a sort of circulation of electricity from one
part of the animal to another, and this either through an arc or
through the fluid itself of the arc alternately, as the physicists have
observed. Whereby forsooth it is established that such a circulation
is characteristic, not of the torpedo alone or of similar animals but
perhaps of animals generally when our devices are employed. More-
ever, as in the latter so in the former, there are absent both sensa
tion of a relatively gentle breeze, and attraction or repulsion of very
light bodies, and finally indications of the slightest motion in elec
trometers hitherto invented.
But even our animal electricity has this in common with this
kind of electricity, that it requires no previous device, friction for
example, heat or other things of this sort, by which it should be
excited, but it is ready as if by nature and continually prompt, and
is produced on contact alone.
Nay, so great promptness for action is in this electricity of ani
mals, which we have experienced, that if the vertebral column is
allowed to be touched by an insulating body in a place where it is
armatured, not rarely contractions are produced, particularly if the
animal has been recently slaughtered and prepared. Moreover, they
often occur if the same insulating body is so pressed against metallic
foil that the contact of the foil with the nerve emerging from the
vertebral column is either augmented or changed, but I know not
whether this can be affirmed concerning the torpedo's electricity.
Moreover, this one thing seems particularly proper and peculiar
of the torpedo and cognate animals that at their will and pleasure
they can direct electricity outside the skin, and expel it so that it
completes its circulation outside the body, and with such quantity
and force that it exhibits a spark, if we heed the physicists, so that
it produces a concussion and violent sensation and sometimes makes
LUIGI GALVANI 6/
such an impact on the animalcules that fall into the path of its cir
culation, that it either kills or stupefies and terrifies them. But per
haps in animals of this class this indicates more abundant quantity
and force, not really a different nature; and perhaps some time,
devices can be found whereby effects of this sort can be obtained in
other animals also.
Moreover, electric circulations of this sort, discovered and de
scribed by us in other animals, not only their strength and relations
but also their ways and instruments, perhaps will be able to shed
some light on the same circulation in the torpedo and cognate ani
mals, and again from more diligent discussion and observation of
these animal organs which are fitted for this function, these of ours
will be able to receive light. The instruments perhaps will be simi
lar, and the terminals of the electric circuit, namely muscles and
nerves, the same.
These things concerning the nature and character of animal elec
tricity: now a few things concerning its source. This I should think
to be not dissimilar from that which physiologists, up to the present
time, have indicated for animal spirits, namely the cerebrum. For
though we have indicated that electricity is inherent in muscles,
yet we do not concur in the opinion that it emanates from them also,
as from its proper and natural source.
For since all nerves, both those to the muscles and those which
go to other parts of the body, seem to be altogether the same, as in
kind so in nature, who will rightfully deny that all carry fluid of the
same nature? But already we have shown above that electric fluid
is carried through the nerves of muscles; therefore it will be carried
through all: therefore from one common source, namely the cere
brum, they will drain it, from the source and origin of all: for other
wise there would be as many sources as there are parts in which
nerves terminate; and although these are very different in nature
and construction, they do not seem suited for the elaboration and
secretion of one and the same fluid.
Therefore we believe it equally true that electricity is prepared
by action of the cerebrum, and that it is extracted from the blood,
and that it enters the nerves, and that it runs through them within,
whether they are hollow and free, or whether, as seems more prob
able, they carry a very thin lymph, or some other peculiar similar
thin fluid, secreted, as many think, by the cortical cerebrum. If this
68 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
prove so, the obscure nature of animal spirits, long sought in vain,
may perhaps appear clearly. But as things are, certain no one of
those hereafter, I think, after these experiments of ours, will call
electricity into doubt. And although, led merely by reason and by
some observations, we first brought this into our public Anatomical
Amphitheater, and many illustrious men had already mentioned it
before, yet never might we think fortune sufficiently favorable to
us to grant to us perchance first to handle it, as it were with our
hands, lurking in the nerves, and to draw it out of the nerves, and
almost to place it under our eyes.
With these premises and indications, I now turn for the first time
to those things which pertain to some explanation especially of the
muscular contractions which are obtained by our experiments,
thence to bring forward those which pertain not only to natural
and voluntary motions, but also to involuntary and pathological,
in order that some approach may be opened to utility of our observa
tions, if indeed it may be permissible to transfer these data of ours,
as not without cause we think, from animals, and especially from
the warm-blooded, to man.
Now from the experiments performed, this fact emerges without
difficulty, that there is a swift and violent excursion of neuro-elec-
tric fluid through the muscle to that nerve whereby chiefly muscular
contractions and motions are excited.
But in what way an excursion of this kind of electricity causes
and induces contractions, whether, for example, by some mechanical
irritation and stimulus striking either the nerves or the muscle fibre
and, as they say, exciting the irritability thereof, or, by the custom
and character of common electric vapor 9 exciting a peculiar and
violent attraction between the particles composing, for example, a
muscle fibre, by its swift excursion through it, so that, as they
mutually approach one another, the fibre becomes shorter; or
whether, as is easier to believe, it is acting for some other reason
not yet understood, is a very difficult thing to be known, and very
much involved in darkness. More and more experiments under
taken on this subject may perhaps bring some light some time.
But now that first comes into question, in what way and from what
causes does such an excursion of electricity from the muscles to the
nerves occur in the experiments described, which will not be difficult
to find under the hypothesis previously described.
LT7IGI GALVANI 69
In the first place, therefore, I should wish it carefully noted that
two things are either chiefly requisite, or certainly highly conducive
to exciting muscular contractions, about which we have heretofore
discussed.
First, namely, something which shall attract the neuro-electric
fluid from the muscle to the nerve and instigate it to exit; then
something which shall receive it as it goes out from the nerve and
either take it back and as it were restore it to the muscles or conduct
it elsewhere and dissipate it. Indeed, if one or the other of that con
ditions is lacking, the phenomenon of contractions will be lacking
also.
Now the things which invite and as it were force neuro-electric
fluid from the muscle to the nerve seem to be chiefly these: namely,
the suddenly removed equilibrium between the internal electricity
of muscles and nerves and the external electricity of bodies com
municating chiefly with nerves; moreover, irritation of the same
nerves; contact of some body, principally conducting, either with
the same nerves themselves or with conducting bodies communi
cating with the same nerves; finally, as it were, some disturbance of
the substance, or friction of the slightest sort, as when, by simple
percussion of the plane on which the prepared animal is lying, con
tractions are excited.
Moreover, it is clear that stimuli of this sort can finally be re
ferred partly to disturbed equilibrium, partly to some kind of im
pulse into nerves, even if very slight.
But the electric fluid, running to a nerve for these reasons, will
be received by some conducting body, which will transfer it from
the nerves to the muscles, if it was produced from the former to the
latter by use of the electric arc; but it will convey it elsewhere, if
it has communicated with nerves alone, or with bodies touching
nerves, and if it has a certain magnitude.
But, these things having been noted and determined, I come to
the explanation of the muscular motions which we have observed,
and first of those which are obtained at the extortion of a spark.
For at the passage of a spark, electricity breaks out both from the
layers of air surrounding the conductor of the machine and from the
nerve-conductors communicating with the same layers; and negative
electricity results on account of them. Hence the intrinsic positive
electricity of muscles runs to the nerves both with its own strength
yo EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
and with strength from extrinsic electricity, more abundant whether
you borrow it from artificial or natural, as received from their con
ductors, and flowing through them, failing both in them and in the
shortly hitherto mentioned layers of air, it will renew the electricity,
and establish itself at equilibrium therewith; not otherwise than as,
in a Leyden jar, the positive electricity of the internal surface in the
production of a spark, flows more abundantly to the conductor of
the former, for the same reasons, and goes out therefrom, just as
the form of a luminous electric pencil openly declares.
Hence it is understood without difficulty whether there is utility
or necessity in the nerves of conductors for receiving and transfer
ring electricity and their constant ratio and proportion with muscu
lar contractions.
Similar seem to be the cause and reason of the muscular contrac
tions which are obtained, on the passage of a spark, in an animal
enclosed in our little glass machine: for the intrinsic electricity of
the muscles seems to flow to the internal surface of the glass through
the nerves and their conductors on account of the same law of equi
librium, so that forsooth as much electricity collects at the internal
surface of the glass as had been removed from the external surface
by passage of the spark.
The reason and cause of the phenomenon seems the same also in
the contractions which occur when the conductors of prepared ani
mals are applied to the external surface of a Leyden jar, or near it,
when a spark is elicited from the conductor of the internal surface.
Indeed, so aptly and clearly is the phenomenon explained by this
law of surfaces and of equilibrium, that I should not easily blame
him who explained also by the same law those contractions which
are obtained in the extortion of a spark from the conductor of an
electric machine, and who should consider the same conductor as a
double surface in the surrounding layers of air, one an internal con
ductor, the other external as regards the animal.
But whether it happens for this or that reason, or any other, no t
yet known, no one will doubt that the causes and reasons of the
phenomenon are the same in those contractions which we said occur
in thunderstormy weather; for at the cast of thunderbolts the same
thing is seen to befall the layers of air surrounding the electric cloud
as befalls those which surround the electric machine.
Finally, there is no one who does not see that, from the same law
LXJIGI GALVANI /I
of equilibrium between the positive electricity of muscles and the
negative electricity of sealing-wax, those contractions easily take
their origin which we said occur when the same rubbed wax is ap
plied to nerves, but fail when rubbed glass is applied; likewise that
from the same law of equilibrium those contractions also derive
which we have already warned will occur when the shield of an elec-
trophore is raised from its resinous surface.
But I come now to those contractions which are excited either by
an arc, or by the contact of conducting bodies with nerves, or by
irritation of the same nerves, or in other ways which we have indi
cated above; and indeed no one has even briefly considered what of
animal electricity pertains to them, how we have referred its nature
and character, without easily understanding how those are devices
suitable and adapted for attracting the positive internal electricity
of the muscles to the nerves, and receiving it and, as we have stated,
for negatively transferring it to the external electric part of muscles.
But, these things being once admitted, it may be enquired how it
is that, if a nerve is even touched briefly by some insulating body,
as happens sometimes if it were armatured, it is irritated by the
same or, if you prefer, by artificial electricity, nevertheless con
tractions appear.
For then indeed there is present both contact and impulse which,
though perhaps slight, could recall neuro-electric fluid to the exte
rior of a nerve: but the body which should receive the same fluid
and either conduct it elsewhere for the sake of equilibrium, or re
store it much more to the muscles, seems to be wholly lacking.
But if the phenomena described are accurately weighed, and the
nature and character of neuro-electric fluid considered, which is
accustomed to find free access and a ready way for itself only
through conducting bodies, and to hasten swiftly from nerves to
muscles, perhaps not even then will the conducting body of an arc
seem necessary as an alternate; forsooth, the fluid and moist external
parts of nerves, or particularly their thick and hard membranes,
or both, will be able to perform this function. Hence perhaps with
the cranium open and the cerebrum exposed, and likewise the spinal
cord removed from its vertebral column and bare, no contractions
of muscles, as we have said, are excited, even if an arc be applied;
but they are excited, if the same be equipped with metallic foil,
which goes far towards taking the place of the missing membrane;
/2 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
but it happens otherwise, as we have warned in nerves which, al
though nature has covered them with thick membranes outside the
cerebrum, it is always useful, though not necessary, to provide with
metallic foil. But if you compare the metallic foil, with which we are
accustomed to cover nerves, as it were to part of the arc, and recall
to mind what we reported concerning the utility of multiple arc
substance in augmenting contractions, perhaps those of the con
tractions which, as we have already said, seemed to occur only on
contact, you will generally repeat from the arc also which is as it
were composed partly of metallic foil, partly of the already men
tioned conducting substances of nerves.
But if these things be granted, perhaps some approach will be
opened to explaining the muscular motions which occur in the living
animal, and which we now advance to consider. For what pertains
to voluntary motions, perhaps the mind, with its marvelous power,
might make some impetus either into the cerebrum, as is very easy
to believe, or outside the same, into whatever nerve it pleases,
wherefrom it will result that neuro-electric fluid will quickly flow
from the corresponding muscle to that part of the nerve to which
it was recalled by the impetus, and when it has arrived there, the
insulating part of the nerve substance being overcome through its
then increased strength, as it goes out thence, it will be received
either by the extrinsic moisture of the nerve, or by the membranes,
or by other contiguous conducting parts, and through them, as
through an arc, will be restored to the muscle from which, as we are
pleased to think, it previously flowed out, from the positively elec
tric part of the same, through impulse in the nerve.
Perhaps in no dissimilar, though less difficult way, if I am any
judge, the occurrence could be hastened in involuntary and unusual
movements, namely if sharp and stimulating agents irritate the
nerves, or the spinal cord, or the cerebrum, and at the same time
summon the neural fluid, so that, having been received by the
conducting parts, it is finally restored to the muscles as if through
an arc.
But in accordance with the different power and faculty of the acid
humors for stimulation and conduction, the contractions also will be
dissimilar; likewise in accordance with the different location which
they will occupy in the nervous parts.
For it is easy to understand, when humors of this sort are poured
LUIGI GALVANI 73
out of the vessels and subside between the surface of the nerve-sub
stance and its investments, that contractions then ought to become
more violent and longer; because then, forsooth, the effused and the
stagnant acid humors will not only irritate the nerve more severely,
but will also constitute, as it were, a more suitable kind of armature
and arc for the neuro-electric fluid.
Hence, in the more severe rheumatic affections, and particularly
in nervous sciatica, in which, according to Cotunius, the humor
stagnates between the sheath and the surface of the nerve, not only
are the pains more severe, but there are wont to be severe and con
stant contractions of the muscles of the affected joint, so that often
the said joint may remain either long or permanently contracted.
Hence perhaps even such violent, such long, so readily and at brief
intervals recurrent, and generally fatal contractions of the muscles,
or convulsions occur when acid and perverted humors stagnate either
within the cerebrum and the pia mater, or within the pia mater and
the dura mater, or within the cerebral ventricles, or within the
surface of the spinal cord or of the nerves and their investments, as
generally happens in tetanus, in which disease it becomes chiefly
noteworthy that at first nearly all the muscles fall into very severe
tonic contractions, although sometimes only one nerve may be
affected for a short time, as in the tetanus which sometimes follows
the puncture of a nerve; then it is noteworthy that the muscles re
lapse into the same contractions, both spontaneously and often only
and when by a slight tremor or percussion of the bed, or surface on
which the bed of the patient is resting. But we have already seen
something similar happen, in prepared and armatured animals in
whom it is permitted that an arc should be applied briefly to one
crural nerve, nevertheless all the muscles not only of one limb, but
of both, fell into tonic contractions, and sometimes recurred into
them spontaneously, either from a mere tremor, or from percussion,
of the surface on which the animals were lying, so that on this ac
count these experiments of ours on this disease and its peculiar symp
toms seem, if not to have discovered the cause and reason, at least
to have injected some suspicion into the doctors.
Now, indeed, these theories concerning contractions of muscles,
both gentle and natural, more violent, and pathological, having been
postulated and considered, it was inevitable that there should be
presented to my mind as it were a new cause and reason for the
74 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
opposite faults, namely paralysis and others, namely the already
explained arrested circulation of neuro-electric fluid, either from
muscle to nerve, or from nerve to muscle.
First, perhaps, it might happen, if a substance of oily or other
insulating nature should beset part of the nerve; second, if a similar
material should involve either the external moisture of the nerve,
or the membranes themselves, or some other parts, through which
the neuro-electric fluid performs its already indicated circulation;
but if the effusion and congestion of this material is promoted by
acid and especially by corroding agents, the substance and texture
both of the nerves and of the cerebrum may be injured. But although
perhaps it seems possible that these things may have some truth,
particularly in those paralyses and apoplexies which invade patients
slowly and step by step, yet, in those which attack them in a moment
of time, it seemed that a far different cause of the phenomenon must
be considered.
While I was revolving these and similar ideas in my mind, there
was presented to me as it were a new cause not only of apoplexy but
of epilepsy, derived chiefly from those things which are often ob
served to occur when artificial electricity is employed in animals.
For just as when artificial electricity is industriously directed
either against the cerebrum, or against the nerves, or against the
spinal cord, for example by means of the conductor of a Leyden jar,
if it rushes into those parts with a certain quantity and force, it
irritates them and throws the animals into violent convulsions ; but
if it injures and violently impairs their substance with a far greater
quantity, it renders the same animals paralytic or apoplectic, or, if
it were more violent, destroys them: so I conjectured that animal
electricity could do the same or similar things in man, especially if,
as common electricity is wont, especially if it should seize and
promptly add to itself those delicate elements whereby far greater
power might be added to it; of which sort would be what come under
the name of acid elements, whatever those might be; and so I thought
that now epilepsy, now apoplexy could be induced by thus con
taminated animal electricity hastening through the nerves either
from the muscles or from other parts to the cerebrum and rushing
into it, according as its force and impetus into the substance of the
cerebrum were more or less, and its contamination more or less
LUIGI GALVANI 75
severe. For It seemed that the excursion and impetus of animal
electricity could be violently summoned through the nerves to the
cerebrum by the quantity and quality of the depraved humors stag
nating in the said brain, and stimulating and injuring the brain it
self or the nerves, or finally, to pass over other things, by any great
and sudden mutation of atmospheric electricity, especially if its con
version from positive to negative is made abruptly, perhaps not
unlike that which we conjecture both the conductor of the electric
machine and the electric cloud to produce in the surrounding at
mospheric layers, either at the extortion of a spark, or at the crash
of a thunderbolt.
Now thus far I assumed that no one failed to see how the causes
reviewed could exercise their forces more violently, promptly and
easily, if acid and stimulating materials were clinging in the cere
brum, than if in the nerves; for in the former they may well desig
nate those diseases as idiopathic, but in the latter as symptomatic:
and moreover diseases of this sort will be also far more severe, and
will occur more readily, if animal electricity, and contaminated at
that, is in excess in the body and particularly in the muscular and
nervous parts. Hence I reflected that diseases of this sort are par
ticularly prevalent in old men, because in them a more abundant
supply of contaminated animal electricity seems to accumulate, both
on account of their intermitted labors and exercises, and because of
the dryness of the parts induced by old age, and primarily the
density of the oily substance of nerves, and finally because of the
diminished insensible perspiration by which so great an amount both
of electricity and, of acid and delicate principles is carried outside the
body; so also I conjectured that these fatal diseases prevail for the
same reason especially when those more severe storms and changes
of weather are threatening, in which there is wont to be a greater
quantity of electricity in the atmosphere, or a little afterwards; for
at that time more electricity is found in animals, so that the con
tractions described, then occurring more often and more promptly
and more violently, seem clearly significant. For these and for other
reasons, then, immoderately increased and contaminated animal
electricity seemed with such force and impetus to be able to rush
and flow into the substance of the cerebrum in a moment of time
that in the same moment of time it injured its structure severely,
/ EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
and ruptured vessels, whence both paralysis constantly and easily
followed and humors were poured out, and having been shed and
stagnating, as often happens, were found in sections of corpses.
These and other things used to come into my mind about the
cause and the manner of invasion of these diseases; but at the same
time I realized that hypotheses of this sort could incur many and
grave difficulties among learned men and perhaps their reprehension
for many reasons, and particularly because they oppose the opinion,
common and accepted in the schools, namely that muscular motions
are performed by an excursus of nerve fluid from the cerebrum to
the muscular parts, not from the latter to the former. But if anyone
among other things should recall to mind that aura, as it were, which,
ascending to the cerebrum either from the lower limbs, or from the
stomach, or from the lower abdomen, epileptics easily and very often
feel and accuse at the moment when they are seized with convul
sions; if then he should consider that sometimes the progress of this
disease is arrested, if a noose or tourniquet is applied to the leg,
which, as it were, impedes and intercepts the way: if anyone, I say,
turns his attention to all these things and to our experiments, he will
easily pardon us, if we have descended to these conjectures. But
these things, as I was saying, I was, as it were, imagining in my
mind, chiefly with this purpose, that they might be recalled to con
sideration by the most learned scholars.
A cause having been suggested, not only of natural but also of
pathological contractions, and the cause of paralysis having been
sought chiefly in the ascertained nature of animal electricity, there
seem to remain some things which should be touched on concerning
the treatment of these diseases.
And in the first place it seems that this can be derived from our
experiments, that, whatever remedies are employed for removing
those diseases, and even electricity itself administered externally,
all these things, if they are going to do any good ought to exercise
their effect chiefly on animal electricity, and either increase or
diminish it or change it in some other way. Which electricity, there
fore, and its status the doctor should have chiefly before his eyes in
treatment.
Therefore, omitting other remedies, whose effect on electricity of
animals diligent investigation and use will reveal and disclose some
day, I immediately turn to the administration of external electricity,
LUIGI GALVANI //
and, in order that the thing may proceed more clearly, I will con
sider it first in convulsive and rheumatic contractions of muscles,
then in paralysis.
But before all, a threefold faculty and function in applying arti
ficial electricity to the human body, in my judgment at least, comes
under consideration; first, namely, that which can be called, as it
were, extemporaneous, and which continuously exerts action on parts
of the human body which are exposed to it, as when it acts through
a spark, and especially through an electric thunderbolt, as it were,
when a Leyden jar is discharged; second, when electricity produces
its action not continuously but successively and with the passage of
time, combined perhaps, and almost I had said with chemicals, com
bined especially with the fluid parts of the animal body, as that
electricity which the younger physicists call balneal; finally at length
that which draws electricity from the animal, as when negative
electricity, as the same physicists call it, is employed.
Let us now consider briefly these individual functions in the dis
eases mentioned. Now as for what pertains to convulsive contrac
tions of muscles, anyone easily sees that, in our hypothesis, these
generally derive either from exuberant and contaminated animal
electricity in the muscles, which, for most trivial causes is summoned
from the muscles to the nerves and to the cerebrum, or particularly
from acid and stimulating principles striking either the brain or the
nerves, or, as often happens, from both causes. If the first, it seems
that positive electricity, as they say, could scarcely, and not even
scarcely, afford any benefit, but rather more injury, in whatever way
administered; but negative electricity, as is obvious, might be of
no slight advantage. But if it were the second, the physician can
promise himself some benefit from positive electricity, if this is arti
ficially directed to the affected nerves; for this can, by its own power,
repel and remove acid principles from the nerves.
On account of these things, the differential diagnosis of convul
sions and their causes should be diligently attended to and investi
gated by the physician: and although perchance both causes may
often be present, nevertheless it should be sedulously considered
which of them is more powerful, and although this is difficult, yet
not all hope is to be abandoned that sometime we may be able at
length nevertheless to accomplish this. Since, for example, there
/8 EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
ent or slightly previous amount of electricity in the atmosphere, and
our experiments prove how much this augments the powers and
effects of electricity.
Moreover a quantity of this sort can be explored and diagnosti
cated by the device of atmospheric electrometers, and also by the
appearance of the clouds, by the time and season of year, by the
tempests of heaven, by the qualities of winds, by the phases of the
moon, and by other signs handed down by illustrious physicists, and
foremost by Bartholinus and Gardiner. Besides these, an excess of
electricity in us can also be indicated by a certain unwonted speed
and alacrity of motions, especially of the eyes, deriving from no other
obvious cause, combined with the greatest variety and inconstancy.
Likewise perhaps suspicion might be moved by those very muta
tions which artificial electricity is accustomed to produce in us,
namely unwonted internal warmth, increased secretions and excre
tions, as of bowels, urine, saliva, sweat, insensible perspiration,
rapidity, magnitude and vibration of the pulses, moreover the use
of foods in which the idioelectric or insulating principles are con
tained, as of aromatous, oily, and spirituous liquors, especially if
perhaps no other causes of these mutations are apparent. Certainly
these are generally accustomed to precede especially the more severe
convulsions, and other affections of the nerves, such as epilepsy,
mania, and others similar.
Moreover, the opposite could warn us clearly of negative or de
ficient electricity. But, indeed, if there were any indications of per
verted or contaminated electricity, they will perhaps be furnished
by some of the discomforts of patients and symptoms of diseases,
which to the doctors are wont to signify the power and prevalence
of acid principles. But let it suffice to have touched upon these, that
another way may be open to investigate and diagnose the varied
status of animal electricity.
But as for what pertains to rheumatic contractures of the muscles,
since these generally take their principal origin from acid and stimu
lating material settling in nerves, it is easy to surmise that in them
almost individual methods of administering positive electricity could
be useful, employed, however, in the following order and plan; that
first that method should be employed which is called "through the
bath", for collecting more abundant electricity in the muscles; then
that which is administered through sparks; finally that which is
LUIGI GALVANI 79
administered through concussion; so that first, forsooth the stag
nating humors may be attenuated by the mechanical and repellent
force of electricity, and then more easily removed from the affected
part by increased impulse.
And no less, for the same reason, could negative electricity also
be advantageously applied in the affected part, particularly by our
method, namely by the extortion of a spark either from the con
ductor of an electric machine or from a Leyden jar, particularly if
the affected part is applied to its conductors, of which some incline
to the machine, others communicate with the ground, which method
could perhaps be rendered more useful, if either large Leyden jars
were employed, or many of them attached to one common conductor,
or larger electric machines, such as in our times are constructed
without difficulty; or much more, if a way should be found whereby
it is possible to direct and impel animal electricity from certain
muscles to certain nerves. For it escapes no one that, of those which
we have suggested, by this method a more vigorous excursion of
animal electricity is promoted particularly through the affected
nerves, most suitable, as it seems, above others, as an aid for dis
lodging, dissolving, and expelling from the nerves principles stag
nant and impacted in them. Hence perhaps muscular motions, which,
as we have said, perhaps arise from the excursion of electricity from
a muscle to the nerves, are accustomed to afford no little benefit
and relief in rheumatic affections, and the more, the more vigorously
the affected parts are moved, even if with some inconvenience and
pain.
But if this new method of administering negative electricity should
be combined with some utility, either in these diseases or in others,
how much greater benefits shall we be able to promise from at
mospheric electricity, if, as we have suggested in artificial electricity,
the affected parts by their own conductors are cautiously and pru
dently adjusted, for example, to the raging thunderbolts and light
nings: was this perhaps the reason why limbs, either contractured
from an early age or paralyzed by disease, have recovered their
natural flexibility, strength, and power of spontaneous motion after
thunderbolts have fallen not far from the patients?
But as to what concerns the treatment of paralysis, I see the sub
ject full of difficulty and danger; for it is difficult to diagnosticate
whether a disease arises from damaged and impaired structure of
8O EFFECTS OF ELECTRICITY ON MUSCULAR MOTION
nerves or of brain, or from insulating material blocking either the
internal parts of a nerve or others whereby we think that the circu
lation of electricity in us is performed. If it can do little good, and
perhaps artificial electricity could do much harm, in whatever way
administered; if the latter, it seems that it could afford some utility,
either for dislodging insulating material, or for augmenting the
strength of animal electricity. But some time perhaps use and ex
perience will reveal the whole subject. But now in closing let us
touch on some neither trivial nor useless conclusions from our
experiments.
From these, then, it seems to be established that both artificial
and atmospheric electricity have far greater power over muscles
and nerves than was hitherto recognized; and that from their
strength especially as great a faculty passes into animal electricity
as in our experiments it was seen that animal electricity has for
motion and to promote its exit from the muscles and its speeding
passage along nerves, and to excite violent contractions of the
muscles.
Moreover, with these things recognized, there is perhaps greater
access than it before seemed could lie open for newly discovered and
more useful methods of administering electricity than those hitherto
ascertained, or for disclosing the causes of agreement between the
vicissitudes of atmospheric electricity and of our own health, and
between some diseases and the sudden changes of the former.
Moreover such experiments seem to suggest that, in the passages
of thunderbolts and of sparks, not only atmospheric, but perhaps
also terrestrial, electricity flows back towards heaven. Or indeed
does it result from this reflux that, when great storms arise in heaven,
mutations and vicissitudes occur in the atmospheric air, not only
on account of principles of diverse kind which it transfers from
various regions of heaven, but also on account of those which it
transfers with itself from earth into the air, if the electric fluid pos
sesses this property, which very many physicists concede to it, that,
of the bodies through which it passes, it expels and dissipates some
of the more subtle principles, but removes others and joins them
to itself? But let the physicists chiefly attend to these matters!
But when such a reflux of terrestrial electricity into the atmos
phere occurs, it could claim for itself either a large, or certainly no
mediocre part in those swifter and great increases of plants which
LUIGI GALVAN1 8 1
the illustrious Gardiner observed after lightning and thunder, and
ascribed particularly to atmospheric electricity associated with
vapors*
Finally, since such contractions of muscles which we have said
occur under storms in heaven afford, as it were, a new and not un
certain indication of atmospheric electricity and its effects on the
animal economy, these could perhaps conduce no little towards re
vealing, not so much causes for earthquakes, as effects in the same
economy; so that on this account it seems not useless to investigate
these same things when earthquakes are raging.
But let there be a limit to conjectures! And now the end.
These were chiefly the things which I communicated to the most
learned men as ascertained about the effects of both artificial, and
atmospheric, and tempestuous, and natural, electricity on muscular
motion which is subject to the will, in order that they might some
time bring about that utility which has been most in our desires.
But what things pertain to the effects of these electricities on
natural motions, on circulation of the blood and secretion of the
humors, these things we will publish as soon as possible in another
commentary, when we have found a little more leisure.
Two Letters of
Bassano Carminati and Luigi Gafoam
Letter from Don Bassano Carmlnatl
Public Professor of Medicine in the University of Pavia,
to Doctor Luigi Galvani, Bologna
I have delayed until now to thank you for the precious gift which,
through the courtesy of our mutual friend, Don Mariano Pontana,
you have made me of the dissertation containing your beautiful,
original discovery on the natural and spontaneous electricity of
animals; I have delayed, I say,until now, in order to offer you, with
my own most sincere congratulatlons,those also of other of my cele
brated colleagues, and especially of Spallanzani, of Barletti, of Volta,
of Rezia, and of Malacarne, who feel with me all the importance of
this your marvellous discovery, and load you with deserved praises.
But if, through divided motive, I have not been among the most
solicitous to congratulate you, I shall perhaps have at least the merit
of imparting to you before anyone else the favorable judgment of
your observations and experiments which has been given by one of
the best judges whom I know in such matters, that is to say our most
distinguished knight and my celebrated colleague, Signor Volta,
to whom first I communicated your dissertation, confident that he
would not fail to repeat your principal experiments, to vary them,
to make new ones, and to carry farther than would otherwise have
been possible the researches on a point so fertile of consequences
most important in the physical history of the animals. Now he has
communicated to me some results of his experiments made in these
last eight days since he began to occupy himself with them; and I
make haste to report it, flattering myself that in amends I am doing
a gracious thing, opportune to bring into greater light a discovery
which does so much honor to all Italy.
And first as to artificial electricity applied to frogs prepared in
various ways, either cut up or entire, he has observed that their
sensitivity, or irritability, is remarkable in all cases, though varying
according to the different preparations : being greater in the decapi
tated than in the entire frog, especially when a needle is driven into
the dorsal spine and the electricity made to pass through this route
to the extremity of the hind legs: much more after the frog is cut in
such a way that only the legs remain and these attached to the spine
by the two crural nerves, everything else being removed; and incom
parably more still, if this spine and parts of the said nerves are
85
86 LETTERS OF CARMINATI AND GALVANI
covered with delicate metallic foil. Up to this point, then, his experi
ments agree with yours, which are found by me, and by others, most
accurate, and described with all frankness and with greater elegance.
But the most illustrious Signor Volta has wished to proceed to
determine and reduce to degrees and measure the force of the elec
tricity required in all these cases to excite in muscles the contrac
tions and the movements of your descriptions. He has found, then,
that, for the live and intact frog, an electricity that is barely spark
ling suffices, and that it raises the electrometer quadrant of Henly
eight or ten degrees, and even less suffices of the electric charge of
the Leyden jar, that is, five or six degrees, placing the frog in the
circuit of the discharge. When the frog is decapitated, with the
needle fixed in the aforesaid manner, there suffice of the electricity
of a simple conductor, if this is reasonably large, three or four de
grees of the same electrometer, or less of the charge of a Leyden jar.
When, then, the frog is prepared in the manner already indicated,
so that the dorsal spine is connected with the legs only by the crural
nerves diligently exposed, a current so weak that it does not move
the quadrant electrometer even one degree, and a phial electrometer
of Cavallo only eight or ten degrees (with pendula of straw after
the manner of the same Signor Volta) is sufficient to produce the
customary convulsions in the frog. And employing the Leyden jar,
one or two degrees of this same delicate electrometer suffice. But
still there is no respect to the sensibility of the animal, when they
are wrapped as above, both spine and parts of the nerves, with
metallic foil: then less than one tenth of a degree of this same elec
trometer, which may be the charge of a rather large Leyden jar,
produces the effect of convulsing all the muscles of the animal thus
prepared.
But how shall one measure so imperceptible a current, which does
not even perceptibly move such an electrometer with most delicate
little strips of gold foil, after the manner of Bennet? Here our Signor
Volta has recourse to his electrical condenser in the English Trans
actions for the year 1782, and particularly to that of a sort of glove
or cap applied to the smooth head of the phial electrometer men
tioned: which new device he has described and explained diffusely
and elaborately in his letters on electric meteorology, published in
the Journal of Dr. Brugnatelli of Pavia, entitled Physical Library
of Europe^
1 Volume I, 1788.
LETTERS OF CARMINATI AND GALVANI 87
Such a weak current of electricity, and entirely Imperceptible to
every other test, producing such manifest effects In the prepared
frog, constitutes it an electrometer ten times more sensitive, at
least more sensitive with gold foil, for the charges of a strong con
ductor and of Leyden jars.
Having reduced to this minimum the artificial electricity, which
can convulse the frog, Signor Volta concludes that at these limits
and moderate degree of force spontaneous electricity acts, or rather
intrinsic animal electricity of the animal, when prepared In the same
way; its muscles contract and go into convulsions, by simply apply
ing one end of the arc conductor to these muscles, and the other end
to the metallic armature of the nerves. Starting from this idea, I
thought that he would be able to discover in what part in this little
electric machine, or rather Leyden phial, lies the excess, and in what
part the deficiency, of electric fluid, despite the inability to show it
directly with any electrometer; and he believes that this has been
achieved.
I thought to apply the Leyden jar charge at such prodigious weak
ness as eight or ten hundredths of a degree, entirely imperceptible,
as if he said to every electrometer to apply it, or the positive part,
to the nerves, and the negative part to the muscles; and now, in a
contrary sense, with the idea that where the excess of fluid in the
prepared animal was on the side of the nerves and the deficiency on
the part of the muscles, the concussion would not ensue from this
application to both terminals, nerve and muscle, of homologous
electricity, (as no discharge follows testing in the same way two
Leyden jars), and on the contrary would follow application of the
contrary electricity.
The result corresponded in many tests made in these past two
days on three frogs, and especially in one; that is, they had con
stantly the customary contractions and convulsions, the hook of a
Leyden jar applying the charge internally by excess to the nerves,
and the body of the same jar to the muscles; and none operating
inversely. On the contrary, the phial being negatively charged, con
vulsions occurred on applying the hook to the muscles and the body
to the nerves, and not inversely.
Of course this was true always when the charge of the phial was
so weak that it exceeded either none or little the ten hundredths of
88 LETTERS OP CARMINATI AND GALVANI
a degree indicated above: since, when it was four or six times greater,
it produced the effect in whatever way it was applied. From these
beautiful and delicate experiments, Signor Volta concluded that the
deficiency of electric fluid exists on the part of the nerves, not the
excess, as you had believed you could advance on other conjectures.
Therefore, our distinguished Signor Volta wishes the contrary of
your opinion, which is not yet held as a settled thing, because based
on experiments of the utmost delicacy, made by him in number,
but not yet repeated as much as he would wish.
Meantime, while the above celebrated physicist attends to these
experiments on frogs, that they may be perfectly reasonable and
easy to perform, let not others among us cease to experiment on
other animals, including warm-blooded; and already are verified the
tests made by yourself on birds and quadrupeds. Those of my own
Institute are now proposing some experiments, which can be of very
useful application to medicine, on the action of poisons and of drugs,
especially of those which are called medicinal and heroic.
To do these experiments I have already made suitable arrange
ments with Signor Volta; and so, after having conferred with him
about it, I have already performed a trial of experiments directed
to determine the action of opium, of camphor, of musk, of snake-
venom, of cherry laurel, of bitter almond, and others, with regard
to exalting and abating animal electricity, applying these materials
now to nerves and now to muscles, now in substance, and now by
means of infusion, holding the animal for some time immersed, either
intact or deprived of some parts. Within a short time I shall perhaps
be in position to communicate to you the principal results of these,
my researches.
We purpose still to investigate what may be the electric action
of nerves on other parts than the muscles, that is on membranes and
on vessels; and in what manner it modifies the circulation of fluids,
the secretions, and other things; if indeed in this we have not been
already forestalled by you, as supposes our most esteemed friend,
Don Mariano Fontana, who esteems you as much as I, who do not
allow myself to be surpassed by anyone in the honor of being, with
the most distinguished consideration and greatest respect, yours.
Pavia. 3 April, 1792.
Letter from Doctor Luigi Galvani to
Professor Don Bassano Carminatl
I have finally written out, in some manner, amid the scarcity of
time in which I live daily, the few considerations pertaining to the
experiments of the illustrious Signor Volta which I promised you
in my latest. I beg you to submit them to the sagacious discernment
of so illustrious a philosopher, to whom I entrust them and on whose
judgment will depend principally their fate. They are expressed
roughly and in confusion; in such a manner, that is, as the brevity
of time and my scanty ability have permitted. But whereas he be
lieved them not entirely useless, you can embellish them with the
elegance of your style; therefore I consecrate them wholly to you.
The learned author, then, as you advise me, has measured the
quantity of artificial electricity which, in a frog prepared and arma-
tured in the manner proposed by me, suffices to produce muscular
contractions, and has found this to be the tenth part of a degree of
what is necessary to render it sensible to the most delicate elec
trometer, and thence he draws two beautiful conclusions: one is
that the frog prepared in a similar way is an electrometer ten times
more sensitive and delicate than any yet invented, and even than
his own most delicate ones; the other is that a similar minute quan
tity of animal electricity will suffice to produce natural and spon
taneous movements in the aforesaid animal; thence there comes by
legitimate deduction the prodigious force which extrinsic electricity
must have, whether it be terrestrial or atmospheric, in animals and
thence in man, and therefore he had not yet sufficiently learned what
and how great changes occurred to infer this either in one or in the
other.
In short, in a very brief time he has shed no little light on the
most interesting point of the influence of terrestrial and atmospheric
electricity on our actions, and on the alterations and diseases which
frequently afflict us; and in other animals he has no little encouraged
the doctors to continue the use of artificial electricity, making them
hope, with every reason, no small advantage.
He has made other beautiful experiments concerning the seat of
the excess and of the deficiency of this animal electricity, referred to
muscles and to nerves.
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He has applied to the animal a Leyden jar charged on the internal
surface, first in such a way that the hook corresponded to the nerves
and the external surface to the muscles; then the opposite, and that
in order to apply electricity from them according to my opinion,
homologous in the first case, contrary in the second, I having sus
pected that the external part or surface of the muscular fibre is nega
tively electric and the internal positively, of which the nerve is like
the conductor, invested with insulating material, to hinder the too
easy and harmful dissipation of the electricity.
He having therefore observed that in the first case, when, that is,
the hook is applied to the nerve, the contractions occurred, and not
otherwise when the aforesaid hook is applied to the muscles, he
began to suspect that the excess of that animal electricity is on the
external surface of that muscle, the deficiency in its internal sub
stance, to which the nerve corresponds, otherwise they would have
been produced from homologous electricity, which is contrary to the
established laws of physics concerning the same electricity.
Such just reasoning, founded on physical laws, and deduced from
experiments by so accurate an experimenter and excellent a philos
opher, you see well cannot but deserve my true approbation and the
prompt change of my opinion, I certainly having no other goal in
my researches than the pure and simple truth, with which alone can
be joined that utility which I desire that some day these my re
searches and conjectures, such as they are, may bring.
I will beg you only to submit to the consideration of the learned
philosopher this my doubt, I know not how important: that is,
whether the contractions produced in case of applying the hook of
the flask to the nerve could have been derived either totally or in
part from the irruption into the same nerve, and thence into the
internal surface of those muscle fibres, from the irruption, I said,
of the electric fluid of the jar itself used in the experiment? For al
though in my hypothesis there ought to be two electric currents,
that is the animal, or that of the internal surface of the muscular
fibres, to which the nerve-conductor corresponds, and the artificial,
that is, that of the hook, and although, I said, there ought to be
between them these homologous electricities, yet it will be perhaps
difficult that they should have been equal in every thing, both in
quantity and in strength; but it will seem also sufficiently likely
that the artificial current of the jar, though very slight, should have
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overcome the natural electricity of the nerve, that is, that of the
internal surface of the muscular fibres. Thence a part of the elec
tricity of the hook will have had to pass through the conducting
substance of the nerve to the internal surface of the muscle fibres to
render this electric on an equality with the internal surface of the
jar, and therefore the effect, that is, the contraction, will have been
a product not so much of the electricity existing in my sense within
the internal part of the muscular fibres as it is much more of that of
the jar added to it, mediating the application of the hook to the
nerve.
If the courteous Signer Volta agrees with me in this, it would not
prove difficult to explain the lack or smallness of the aforesaid con
tractions on applying the hook to the muscles, be it either to the
external surface of the muscle or, I would say, of the animal phial:
since, in such a state of things, the artificial electricity applied to
the aforesaid external surface will surely have determined the exit
of the animal electricity contained on the internal surface of this
phial, but will not have been able to join it. This supposed animal
electricity, as seems likely, in its quantity and energy being no little
inferior to the artificial, considering singularly the dissipation of it
which it seems must occur necessarily and continuously in the cut
ting and preparation of the animal, it will not cause surprise if it
has not been sufficient to produce the sensible effect, which the arti
ficial produced, or has not been able to produce it, except very slight
and far inferior.
From which it results, I believe, that if the artificial electricity
increases and this is applied equally to the muscles of the prepared
frog, then determining it by the laws of the charge and discharge
from the surfaces, there will go out from the muscle through the
nerve a greater amount of natural electricity and with greater force;
this is then sufficient to excite the contractions, or be they muscular
motions, as I have proved many times by experiment; having con
stantly observed that a quantity of artificial electricity almost mini
mal suffices to induce contractions when it is applied to the nerve;
it does not suffice when it is applied to the muscle. Therefore it
would seem that, notwithstanding the beautiful experiments under
taken by the illustrious Signor Volta, to the contrary, the hypothesis
could prevail of excess in the internal parts and surfaces of the muscle
fibre, of deficiency in the external.
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But even though the most illustrious Signor Volta should be will
ing courteously to grant me this, I shall not therefore remember his
experiments without great appreciation for their great utility; while
the same could conduce, assuming the aforesaid conjecture of the
animal flask, to the clarification of a most interesting point of physi
ology, what is the physical cause of voluntary motions? and of one
of the most difficult phenomena to understand in whatever system
thus far invented concerning muscular motion. In fact his experi
ments will clearly demonstrate that the electric fluid can have
muscular motions directly not only from the muscle to the nerve but
starting from the nerve to the muscle, or be it from the brain to the
muscle, and can occur not only through the means of the discharge,
but again by means of a forced and impetuous overcharge of the
supposed muscular phial: this being admitted, who does not see how
happily successful is the explanation of voluntary muscular motions?
To excite these, the mind needs only, from the brain where it
resides, with its marvellous and incomprehensible power and com
mand to determine a greater quantity of animal electric fluid, col
lected in the brain, through the nerve-conductor to the muscle, or
else perhaps to give a greater impulse to that which naturally exists
in that muscle; the contractions then will occur no otherwise than
they did with the most illustrious Signor Volta, when he added to
the animal electricity of the nerve a little bit of artificial electricity
and in consequence increased the impulse and the action of that
which was static on the internal surface of the muscular fibre, in a
sort of inertia and of idle equilibrium. But when electricity attaches
itself to a surface of a Leyden jar, it goes out from the opposite
surface by the law of equalization and of equilibrium of the two
surfaces, and as much goes out from one as attaches itself to the
other; therefore, attracting the same in the supposed muscular
phial, as much neuro-electric fluid as will run from the brain through
the nerve to the internal part, or be it surface, of the muscle, so
much of it will go out from the opposite surface, or be it external
part, of the same, that it is already always irrigated with conducting
fluids, suited to disperse it and carry it out of the body, and thence
there will always be room for a new supply and charge; in my sup
position, the nerve, so much more than being a conductor of the
animal jar, invested with insulating material, will never give place
LETTERS OF CARMINATI AND GALVANI 93
naturally to spontaneous discharges, which sometimes follow through
union with atmosphere in the artificial jar.
Admitting such a constant ingress and egress of the said neural
fluid from the muscle by known and constant laws, who does not
see quickly that it is easy to explain it, how constantly the aforesaid
fluid runs to the muscle without any of it accumulating therein
either in excess or in a way which should impede the addition of a
new supply, either naturally flowing from the brain to the same
muscle, or determined there by the mind, a phenomenon which
certainly in none of the systems hitherto invented is easily under
stood.
The experiments of such illustrious professors, and the easy ex
planation of such difficult phenomena, induce me for certain very
willingly to change my opinion concerning the action of the mind on
nerves, and the direction of the animal electric fluid in voluntary
motions; the more, because some experiments tried by me a little
while ago seem to confirm this same direction from the nerve to the
internal surface of the muscle, and the demonstration seems not less
suitable than the opposite to excite muscular motions.
I have presented, as I mention in my little work, the feet of the
prepared frog to the external surface of a Leyden jar charged in
ternally, and have observed that the contractions occur at the
extraction of the spark. I have then, moreover, in a dark place at
the external surface of the same jar, likewise reversed the external
surface of another small jar similarly charged, out from which sprang
the conductor with its point bent in the opposite direction to the
aforesaid surface, and I have seen that at the extraction of the spark
from the former, the luminous tuft of the conductor of the latter
went out instead of reviving, as follows when the aforesaid con
ductor is reversed at the external surface of the jar indicated.
Such disappearance of the luminous tuft demonstrates that, in
the act of extraction of the spark from this jar, the electricity of the
other is forced into a retrograde motion and to direct itself no longer
from the cavity to the conductor, as it did when the vanished tuft
reappeared at the extraction of the spark, but certainly with the
opposite direction, that is, from the conductor to the cavity of the
same flask. It would have taken this opposite direction more easily
and more promptly, if there had been near the point of the aforesaid
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conductor such a conducting body as communicated with the
ground; while then the electricity of the earth, determined by the
same law of equilibrium of the surfaces to the internal surface of the
same flask, entered through the aforesaid conductor to betake it
self to the same surface. The same thing, it seems, must also happen
to the electricity of the animal flask, whence occur the contractions
when its external surface reverses itself, or be it the feet at the ex
ternal surface of the flask, from which the spark is extracted, and
they are greater and stronger if there is near its conductor or the
nerve, in the act of extracting the spark, a body similarly communi
cating with the earth.
It seems that the same ought to occur if the air contiguous to the
aforesaid conductor contains much electricity, or else if there be
nearby some body which can supply some. Thence perhaps are ob
tained sometimes the aforesaid contractions, if there is near the feet
of the animal a cylinder of powdered sulphur, and they are also and
at such times greater if there is applied simultaneously to the ex
posed spinal cord a glass cylinder similarly excited, although they
do not occur with the sole application of that glass cylinder although
well rubbed; since by means of the negative electricity of the sul
phur the electricity flowing from the spinal cord is compelled to
return to the internal surface of the muscle from which it departed;
and the electricity is determined, be it by the air or by the glass,
to make its way into the spinal cord, and thence much more to com
pel the retrograde motion of that animal electricity.
Whence it results that the same being repelled by two forces
towards the said internal surface, the effect is too great, and thence
arise those contractions which we said are stronger; which after
wards fail on the application of the activated glass alone to the
spinal cord, perhaps because, dealing with homologous electricity,
there can enter into the spinal cord only that small portion of vitre
ous electricity, which overcomes the animal electricity, and that
with difficulty, remaining by nature strongly adherent to the glass.
Thence it is that in case of employing sulphur and activated glass,
to make the aforesaid contractions much more perceptible, in the
manner described, it helps a great deal, before trying the experi
ment, to armature both the spinal cord and the muscles with tin
foil, and to apply to them any metallic conductor; on the contrary,
so great is the strength of this armature that then the contractions
LETTERS OF CARMINATI AND GALVANT 95
are obtained by applying to the aforesaid muscle conductor the
powdered sulphur alone, and that very likely because the discharge
from the external surface of the muscles takes place more easily,
and because of a prompter return of the animal electricity to the
internal surface of the muscle through the nerve, and an easier in
troduction into it of whatever electricity is found in the contiguous
air.
From the outcome and result here expounded, if I do not explain
and express myself ill, it is clearly understood that muscular con
tractions can be produced by natural electricity in the living animal
from three different causes: first from a violent overcharge of the
muscular cell induced by the powers of the mind, and this seems to
occur in voluntary motions; second from a forced overcharge, as
when, by some external agent or irritation, the aforesaid electricity
is determined to descend forcibly and violently from the brain to
the muscles, as in reflex motions, and I call this action an overcharge,
assuming that some charge, as seems very likely, is in the muscle
constantly and naturally; third and finally from a charge equally
violent and forced, as will occur when some external agent, applied
to the nerve or to the brain, determines the electricity of the in
ternal surface of the muscle to ascend through the nerve and go back
to the external surface of that muscle.
Given these three causes, it seemed to me that I saw open a wide
field for the felicitous explanation, not only of voluntary motions,
but also of unnatural and violent ones; and of various nervous
maladies and their causes, as also of their relations to terrestrial and
atmospheric electricity, as I shall endeavor to demonstrate in an
other little book of mine which I shall publish as soon as possible,
when pressing occupations do not forbid me.
Therefore, before adopting the explanation and the theory of the
overcharge principally in voluntary motions, I desire that you and
the illustrious professor should judge if ever he could render it sub
ject to any question that it is founded on principles less certain
than those on which is based the theory of the charge, and that it
needs more suppositions than the other; while I recognize the afore
said opinion as founded on the action of an extrinsic and artificial
electricity, whereas this is based on the action of an electricity purely
intrinsic and natural, it is proper and reasonable to suppose, in the
former, that the artificial electricity acts on the nerve in the same
96 LETTERS OF CARMINATI AND GALVANI
manner as the natural, but is not wholly the same; for although it
appears very similar, yet it is not demonstrated, but there remains
room for suspicion that the artificial electricity acts in the manner
of a stimulus and determines the natural to discharge; and it seems
likely, whatever difference of nature there happens to be between
them, through some mutation, or I would say preparation and
modification, that the aforesaid common electricity derives from the
animal machine; whereas in the hypothesis of the discharge there
is no need of any such supposition, but it is sufficient to assume that,
as natural electricity acts in animals dead and artificially prepared,
so it acts in the living; a supposition which, although it is certainly
daring, is nevertheless, as everyone sees, common to both hypotheses.
Moreover the phenomenon of the perennial influx of neuro-electric
fluid from the brain to the muscle through the nerve, without either
the muscle or the nerve remaining full of it to excess, and without
access ever being denied to a new quantity of the same fluid coming
up, it is easy to understand that in a state of quiet of the muscle it
is explained with equal felicity whether on one or on the other hy
pothesis, because the felicity of such explanation springs from the
supposed structure of the muscular fibre like a Leyden phial, which
is equally common to one and the other conjecture. Moreover, in a
state of motion of the same muscle, where this succeeds in the dis
charge of the muscle fibre, it would certainly not impede a new
afflux of the aforesaid neuro-electric fluid to the muscle, but would
render it much more active and abundant, the supposed muscle cell
finding itself, after the motion, charged either wholly or in part.
These reflections, whatever may be their value, render me at
present undecided to which of the two hypotheses the preference
ought to be given, until your judgment and that of the distinguished
author and of your other illustrious colleagues have determined me
more to one than to the other, to which sagacious judgment I submit
both these and all the other reflections hitherto communicated to
you, and on that my opinion and conjecture will always depend
somewhat.
This morning in our Hospital of Saint Ursula, in which the Pro
fessor of Surgery is the learned and my most distinguished colleague
Doctor Gaspar Gentili, excellent master of surgery, I tested, with
my customary devices, an amputated leg and arm, immediately after
the operation, in the presence of the aforesaid professor and other
LETTERS OF CARMINATI AND GALVANI 97
physicians and men of learning, and the flexor muscles of the thumb
and of the adjacent digits were seen to contract, both of the hand
and of the foot, and in consequence the aforesaid digits to move.
The device which I employed was to place a good part of the leg
and of the foot, denuded of their integuments, immediately in warm
water, and then to armature the corresponding nerves of the indi
cated muscles with tin-foil close to their entrance into the same; then
I applied a little conducting metal cap, and singularly of silver, and
I applied it in such a way that with one part it touched the edge of
the tin-foil, and with another the portion of nerve uncovered or
some contiguous part, so that there was, as I suppose, an arc com
posed partly of the aforesaid metals, partly of extrinsic moisture,
which brought back to the external surface of the indicated muscles
the natural electricity of the internal surface, which had ascended
to the place of contact of the nerve, and from that had gone out
through the force of the same contact.
The same nerves were then invested with wax or with some other
insulating body, or else the same bodies were superimposed on the
first armature, and no further contraction then was obtained. There
fore the existence of animal electricity seems proved, and its law in
man also proposed. But I do not wish to detain you with it at greater
length. You will perhaps have been too much annoyed with the
excessive number of things described here and with the prolixity of
the test, but pardon all to the pleasure which I have of conferring
with you, and to my desire of receiving from you those enlighten
ments which from your courtesy and erudition I cannot promise
myself too abundantly. With the truest esteem.
Bologna. 8 May, 1792.
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