J 1 β III; J 1 β IV; J 3 α III; J
3 β;
J 3 γ; J 84 α; K 20 γ are short fragments
J
3 b
is a 4-sided Ms.
J
12 a
is the memo on a piece missing from the text published
K
20 b
is a previous memo, in form of letter to Abbot A.M. Vassalli,
written 1st April 1792
J
87 B the planned lay-out of material in the Paper on Animal
Electricity, not corresponding to this Memorandum
>
II
first memorandum
On animal electricity
(a)
PART ONE
Scientific discovery by mr. galvani, and comparison with
present-day knowledge on animal elecricity
Pavia, 5 May 1792
1. The Dissertation, published a few months ago by Dr.
GALVANI, Professor at the University of Bologna, famous for other
anatomical and physiological discoveries, on the action of Electricity in muscular
movement(b), includes one of those great, brilliant discoveries that make history in
Physics and Medical Science, not only for its innovation and originality but also
because it opens up new fields of interesting and curious research, as well as useful applications.
In the third part of this dissertation the existence
of real Animal Electricity produced by the living organs themselves and not induced by any outside artificial element, electricity belonging to all cold-blooded and warm-blooded animals, which has an organic origin and lasts even in cut
limbs, by an action between nerves and muscles, while there is a sign of life, will be proved with
many detailed experiments
2. Without entering into details on these
experiments, suffice it here to provide a general idea of their functioning and of
their astonishing effects. These consisted of strong contractions of muscles and vigorous movements of the whole limb
(the sort that can be obtained by using electricity) but without employing either strong nor even light artificial electricity, but only applying
one side of a conducting arc to the muscle and the other one to the nerve, the latter being detached and bared or even better coated
largely with a metal sheet (we will convey details of these operations
hereinafter).
3. As everybody with an elementary knowledge of electric science knows, the
conducting arc so simply applied does not induce any electricity. Its only function and
effect is to remove what already exists, to balance the unbalanced electric fluid, moving it from where its quantity or tension are larger, to where they are smaller.
For this reason we call it a conductor or discharger arc.
Should we presume that these animal organs are naturally in such an electrical state, i.e. with unbalanced electric fluid between different parts, if a simple conducting arc suffices to
determine the above mentioned muscle contractions? Rather, we must be sure that in such a situation nothing else but the electrical fluid is able to produce muscular movements, balancing each unbalanced side of the animal, with the help of the conducting arc.
4. Moreover, this conductor arc can be made of one, two or more metal pieces, all or in part, or of other materials conducting electricity such as water, animal bodies, clothes,
wood and walls, provided they are not too dry.
In other words, what is needed to obtain a Leyden jar discharge, is that no insulating body should constitute a part of the circuit, which is the path the fluid has to
take to get from the surface of the jar, which is full of it, to the other one, which lacks electric fluid.
The same is required in the case of the animal, prepared as explained
heretofore, in order that the electric fluid, which remains naturally unbalanced, due to its structure between nerve and muscle, or between the internal and the external parts of the muscle alone (which is more likely), can be conveyed from one end to the other with the necessary speed.
5. So, as the life force decreases the electric power weakens, whether regarding the action, which causes the electric fluid to be unbalanced between opposite parts, i.e. nerve and muscle or the inside and the outside of it, as already said, or regarding the force which pushes the fluid
into equilibrium. This passage, if not completely intercepted, is delayed by many not completely insulating bodies, which are conductors, even if not
very good ones. The floor, the walls, marble or dry wood tables, and carpets etc. are not good conductors; but they are the first that, becoming part of the
conducting arc or circuit, do not help the discharge but retain or delay it in such a way that there are no more convulsions in the animal as we usually had when the animal had more of
its vital strength. Shortly afterwards, when this strength is even more reduced, it is useless to try a chain of people holding hands. For the same reason,
it does not work with a single person used as a conducting arc and the use of the water is
pointless too; finally not even many metal pieces linked together are useful for the
purpose. The experiment is only succesful using a conducting arc made up of one or two metal pieces at most but, if we insert anything
thin, e.g. a piece of paper, that is enough to cut off the free , direct flow of electric fluid which is required to start the muscular spasm.
6. So, in the case of an animal organ, i.e. the muscle connected to
a nerve, we find a significant analogy with the Leyden jar, as its discharge is delayed in much the same way
by interposing the same bodies or it might be completely blocked in case of weak electricity, in which case the discharge might take place with the aid of a conducting-arc entirely made up of one solid metal block.
They correspond in every aspect concerning the different power of bodies to transmit the electric fluid, highest in case of perfect metal conductors, less high in case of less perfect conductors, proportionally smaller with poorer conductors, till we have true
insulators. They correspond in detail: as the Leyden jar can discharge in a rapid, complete way, or more slowly and imperfectly, or even its discharge is
completely inhibited, so the muscular contractions in an animal suitably prepared and connected to the conducting
arc can arise more or less easily or even not at all.
7. Who could doubt that these muscular movements are produced by such an effect of the electric fluid, which is naturally unbalanced between the inner and outer part of the muscles, or between these and the nerves, as happens between the opposite surfaces of a charged jar, and reaches
equilibrium thanks to the above-mentioned arc?
8. That is the combination of experiments and the essence of Mr.
GALVANI’s discovery concerning animal electricity.
It is a really important and original discovery although it has been well known for some time that the Torpedo (Torpedo Ray) and the Electric Eel (Gymnotus) are able to transmit an electric shock as happens in the Leyden
jar. Anyway, since this property is typical of some most peculiar fish(c) and seems to
depend on a particular organ apparatus, as the anatomy of those fish shows, and since it
is up to them to give or not give the shock, there was no reason to think that a similar electrical effect could happen and be so important in the animal functions of all
other living creatures in which this characteristic was not discovered.
As no other animal having more or less this shocking power was never found, and since these electric animals have this power
to such a high degree, it was commonly thought that Animal Electricity was their exclusive peculiarity.
9. Most Physicists and Physiologists shared this opinion, except those who mistook for animal electricity
that induced by rubbing animal and human hair and clothes, thus interpreting artificial external electricity as a natural intrinsic property of living
creatures.
10. This alleged animal electricity, which was nothing else but the usual artificial electricity induced by rubbing, since clothes and hair rubbed against a lifeless body, provided they are kept dry by a mild heating, become electrified in the same way as they might do if rubbed against the skin of a living animal, has been supported by zealous researchers with some even more curious experiments and observations, but of the same type:
weak, spontaneous electricity self-generated in the plumes of live parrots; a weaker one (but not so weak
as not to be detected by sensitive electrometers) generated by a man who, after walking or shaking his arms and body, climbs on an insulated stool and touches with his hand one of those
highly sensitive electrometers, the CAVALLO and BENNET ones.
11. But the rubbing of plumes, either against each other or the skin, when the
parrot bristles them up and they happen to be perfectly dry, suffices to explain the first phenomenon and there is no need to claim the existence of any animal electricity. As for the second, the test with a human being,
it is proved that it is not animal electricity, that it does not stem from any natural function or virtue of the internal organs, but on the contrary it is generated by the inevitable rubbing of the clothes (indeed,
sometimes respiration alone can be enough to induce movement), and observing, as Mr
SAUSSURE has shown[1], that if a person is naked when he climbs on
an insulated stool and touches a sensitive electrometer, the instrument has no reaction.
12. In the same consideration should be kept other experiments of similar type, such as that of the nerves dried in an oven, performed by
COMUS (that famous juggler of physics). In this
experiment he constructed a disk which, assembled like an electric machine and rubbed against fitted bearings, generated electricity. In such a way he purported to demonstrate the correspondence between nervous and electric fluid. In fact, the same experiments can be made with wood and cardboard, dried in the oven in the same way, and I had already designed perfectly functioning electric machines with those materials too(d). Similar experiments on nerves, or other animal parts, can only show to those who do not yet know that every
vegetable, animal, mineral element, properly dried, becomes insulating and "idioelectric", i.e. excitable, by rubbing(e), except for metals which are perfect conductors and
anelectric.
13. I cannot disregard other more peculiar experiments which, thanks to some more apparent evidence, gave even to the wisest a clue or at least a suspicion of the
existence of animal electricity in the true sense. But these experiments seemed to me and
most Physicists to be baseless as well, some of them because of their connection with the phenomen of artificial electricity, others because they were peculiar and unique, i.e. events so fortuitous, that when unexplicably
successful once ( if we are to believe that what was reported did indeed happen and there was no illusion or cheating) they could
not be successfully repeated in further attempts. Of this type is the phenomenon related by
NOLLET concerning a man who, while holding a cat in his arms and rubbing its hair, generated a spark by approaching its nose with a finger and had consequently such a shock in his arm and
body as if a Leyden flask had been discharged on him .
The Very Reverend Abbé VASSALLI(f) maintains that many times he has obtained a similar electric shock and spark by rubbing cats, repeating the experiments of Don Alessandro
TONSO, but the most surprising fact is that which
COTTUNIO relates occured to him while dissecting a live mouse: he was holding it in his left hand and clutched the tail between the little and ring fingers and, by means of a cutter in his right hand he had begun the dissection, disclosing a part of the guts. As soon as he reached farther inside with the edge of the cutter, he suddenly received a strong shock in his arms and chest, the effect of which lasted all day long.
14. Such a surprising phenomenon would be significant to prove the existence of animal electricity, if it had not left much doubt on the event itself and on its cause, since the experiment was successful only once. Therefore, I will disregard all these experiments whether uncertain or ambiguous, which we may not trust much, and which
it suffices to outline briefly. I will, however, explain in more detail a specific experiment, which I tested more than once and which has impressed me
much, and which seems to me to prove something.
This experiment was related somehow obscurely (due to some form of restraint, I believe) in some theses in Latin printed two years ago by Ab.
VASSALLI, professor of Philosophy at Tortona(g) who, on my request, was so kind as
to explain it to me; since then I have repeated it sometimes successfully and sometimes not (for
what reason I know not).
15. This experiment consists in collecting
urine in an insulated metal basin from which we have signs of negative electricity, and not
particularly weak but sometimes quite strong, so much so that it causes the pendulums of a
CAVALLO electrometer to diverge eight, ten or more lines.
At first I thought this power could be produced by the scattering of the drops, like
negative electricity generated in a waterfall (that is a discovery of the Physicist
TRALLES) and in the water jets of artificial fountains, as I verified myself (whether this electricity is excited by the frictioning of the drops and the steam with each other and against the air, as supposed by Mr.
TRALLES himself, or is originated by the evaporation of these drops, which form a thin spray like smoke or fog, transforming themselves from drops to elastic vapour, as is much more probable and that
is what I explained at length in my "Letters on electric meteorology"(h), so that the author himself abandoned his first theory and agreed with me). As I was saying at the beginning I thought the negative energy, that was sometimes
measured in the collecting basin, was produced by the scattering of drops, and from the smoke and the fog, coming from a gush of urine.
But I could hardly believe that such a small gush as urine makes leaving the body and also the small quantity of spray produced, as well as smoke and vapour, could be enough to generate such a significant amount of electricity.
My doubts increased more and more when I tried to push the hot urine out of a large syringe, with more strength than what happens when it expands naturally. With those tests, repeated several times and in various forms, I have never had the least sign of electricity.
Therefore I started suspecting, and I almost believed, that the electricity
in urine, when it leaves the body, is real animal electricity. However I was not sure yet. I needed more
decisive proofs to defeat my scepticism about animal electricity.
16. Until now, I have illustrated the experiments and observations made by Physicists considered by most of them valid and able to demonstrate the existence of
real animal electricity. In fact we could not deduce anything else, since most of these experiments are misinterpreted and others are at least uncertain, as we observed, and none is conclusive or has all the characteristics needed to exclude
any possibility of doubt. A large collection of such experiments, both good and bad, is available in the valuable works of BERTHOLON, GARDINI, VASSALLI, and in further pamphlets and memoirs.
17. After having briefly related the experiments and the real facts on which some Physicists believed they could base the
alleged animal electricity, experiments where we have indeed visible signs of electricity, but probably not real animal
electricity, it will not be malapropos to say something also about the merely abstract conjectures and
hypotheses of some Physiologists on animal electricity, conceived in a more or less proper way,
whether in a determined and fixed or indefinite and undetermined sense.
Those Physiologists who thought of it in a more vague and abstract way preferred to consider the supposed
animal spirits or nervous fluid, which, according to the main opinion, take the external impressions to the common sensory system and produce muscular contraction and the associated movements, passing from the nerves to the muscles of a each limb as an effect of
will power. They thought these animal spirits serve the sensory system and the voluntary movements in the shape of a very thin, mobile and effective fluid of the same nature
as light, the ether and electric fluid(i). In this way they could explain the instantaneous speed with which the fluid must pass through to yield the above-mentioned effects immediately.
They were forced to consider the nerves as conductors of these animal spirits, or nervous fluid, as metals are conductors of the electric fluid, without defining the real nature of this animal fluid, just calling it electric, ethereal, etc., almost metaphorically, to point out the similarity in its action to those thin and active fluids, fire, light, air and electric steam.
Had they persisted in the analogy with this
last, they could have assumed that it has an electric nature just by observing the function of this fluid; but this
explains nothing.
Well, those Physiologists, who had such vague and indetermined ideas, should
not be included in the number of those who believe in the existence of animal electricity, even though they often used the name of electricity wrongly.
18. But there were many others who proceeded further with the
afore-mentioned analogy between nerves and conductors and, making more conjectures,
came to suppose that these animal spirits have not the nature of an ethereal fluid but an electric
fluid, and they decided to declare their identification with this fluid.
The authors and the supporters of this theory, with Mr.
SAUVAGES as leader(l), based it on the well known power of
electric fluid to stimulate the muscles. In fact, when a muscle of a dead animal or a cut limb does not react to any mechanical or chemical stimulus, a little electric fluid stiking the muscle with a weak spark, or just flowing sufficiently quickly
through it, is able to liven it up and cause it to contract.
From this they wanted to deduce that since the electric fluid is the most efficient of all and the primary cause of every reaction and movement of muscles, it is most probable that nature employs it for this purpose in
the animal economy.
Further confirmation of the conjectures of our Physiologists was
given by the fact that Nature uses it in the afore-mentioned electric animals, viz. the Torpedo
Fish and the Electric Eel, etc. Nature is very generous towards these animals and loads them with
plentiful electric power, which also bursts outside at will when the animals want to give a shock to a disturber or to someone touching them directly, or by means of a good conductor; in all
other animals Nature is economical and retains it only for inner use, i.e. animal and
vital functions.
Therefore we could say that to the first it has given arms and
a battery in order to fight and shoot down the enemy and to catch their prey (as generally they do using such a powerful electricity, not only as
a defence but also to feed themselves by catching stunned fish using an electric shock); to all
other animals Nature did not give any electricity or any power to shift and move the natural electric fluid, except for what is sufficient and necessary to
control movements and functions, in brief, the inner animal economy.
Therefore they presumed that natural, inborn electricity, i.e. the power to unbalance
within, if not without, the electric fluid of the organs themselves and to conduct it from one side to the other of
these same organs, was an element common to every animal and not only limited to some particular fish, and restricting their capacity to
shock and stun anybody stumbling on them.
19. Such were, or must have been (as even on these matters we do not think that they provided conclusive
explanations) the conjectures and assumptions of several Physiologists concerning
electricity, if not in a proper sense, i.e. characterized by the well known effects of attraction, sparks etc., some kind of
movement of electric fluid, devoted to animal functions especially those with a direct link
to the action of nerves on muscles and to the sensory apparatus. They imagined a movement or an action of this fluid, though no external sign of actual electricity was evident, none of the usual effects which can be related to it, except for the case of those particular fish already mentioned which can give an electric shock.
It must be remarked that these mere hypotheses and vague theories were not much considered by many other
Physiologists, who in fact contradicted them, on the grounds that actual, recognizable electric signs and conclusive direct proofs were lacking(m) as well as because there was little or
no conformity with the known laws of Electricity(n)
20. But even were all of them, both Physicists
and Physiologists, to agree that the electric fluid is the primary cause of muscular
movement, the same fluid with which the action of the nerves is exerted on muscles in animals, which is far from true, since most Physiologists ascribe this action to a completely different cause (the more sincere admit they do not know, nor
do they understand by way of what agent or how it works); were this so, I repeat, this hypothesis, uncertain and vague to the greatest extent, could not have been
farther from discovery that proves the existence of animal electricity with direct experiments and
places it among the number of demonstrated truths. What a difference there is between the first theory, made only of assumptions and suppositions, and the other one clearly and conclusively demonstrated. This task was accomplished by Mr.
GALVANI, who deserves all the merit for the originality of this great and wonderful discovery .
21. And indeed we must consider FRANKLIN's discovery on the nature of electric fluid and lightning less original or wonderful because this idea had already been proposed by
NOLLET and others who had figured it out and
wanted to explain lightning and other phenomena by electricity.
By mere conjecturing, they figured out the presence of electricity in thundery clouds. But it was FRANKLIN who actually discovered it and explained it. They formulated
hypotheses, at most, while he proved the phenomenon and included atmospheric electricity in the number of experimentally verified facts of Physics.
Similarly, our GALVANI, who proved
beyond doubt the existence of animal electricity, while others only imagined it but were not able to verify it (except for the Torpedo
Fish and the Electric Eel) deserves the merit of this original discovery no less than the American Philosopher
for discovering the electricity in clouds.
22. To tell the truth, if we compare the two discoveries there is
one fact that could give less importance to that of our Italian Scientist. It is
this: we already had something verified about animal electricity, i.e. the Torpedo and
other Electric fish. Nothing, however, had been demonstrated concerning the natural atmospheric electricity discovered by
FRANKLIN ; there was only surmise.
If we had to be strict with Mr. GALVANI, his discovery could be similar to
that of MONNIER(o) on the electricity of clouds, not necessarily stormy, rain and snow clouds, and
fog, even the clear sky, when only the electricity of thundery clouds was then known.
Therefore, as a result of such powerful noisy electricity in thunder clouds we came to know the light and calm electricity which prevails in every part of the atmosphere. Similarly we pass from the strong and shaking electricity of the Torpedo Fish, the Electric Eel, etc, (the only
then known animal electricity) to the incomparably weaker electricity in all other
animals.
23. However, in order to give due importance to our Author, we must consider how easy
it could be to go from thundery clouds to those of every other state of the Atmosphere. Since this electricity, although weak,
is not far from the ground and is still sensitive to delicate electrometers, it did not take too long to
discover it. Indeed, it was more difficult to pass from the electricity of so-called
"lightning" animals to any other one, since the electricity is so weak in these that it is impossible to feel any shock, nor for a delicate electrometer to detect it. In these situations it
is normal to think up a trick to detect it (we are not speaking about the anatomical preparation required),
to let this weakest electricity occur in specific organs of the animal.
24. I would make one more consideration about the comparison between the
discoveries on atmospheric electricity and any others about animal electricity. Concerning the
first, we can consider the discovery as the more important one, since it has given rise to more useful practical applications,
viz. the discovery of the power of electricity in thundery and lowering clouds in order to preserve
buildings, ships, etc., from lightning damage. Consequent upon then discovering a
more or less weak electricity, which persists after the storm till the sky clears, we
have better theoretical knowledge which contributes to clarifying many meteorological phenomena but, at the moment, giving
little or no advantage to primary needs, neither does it seem to promise it. On the contrary the discovery on animal electricity, which demonstrated that the shock induced touching a Torpedo
Fish and an Electric Eel was a real effect, was not the first and oldest one but the
latest, most recent discovery of Dr. GALVANI, which demonstrates that every animal has
its own extremely weak electricity, unable to give any shock but able to induce muscular
spasms and movements, was the most productive for its useful applications to applied and theoretical
Medecine.
Revised and completed by John Coggan,
Oxford University
