Part 3
I extended an iron wire, two hundred and fifty feet in length, around my chamber, taking great care that it should not any where touch itself, and made its extremities to terminate at a table which I had prepared for the experiment. One of these extremities being brought into communication with a pile composed of fifty plates of copper and zinc, I held the other in my left hand, and with my right touched the summit of the pile. The Galvanism then proceeded from the bottom of the pile to the summit, traversing a portion of the arc formed by the animal machine. By the effect of this passage, we may therefore form some opinion of the celerity of the Galvanic current. Its rapidity was such, that neither I nor any of those who repeated the experiment publicly, were able to determine the degree. The truth of this proposition is confirmed by experiments lately made by the celebrated Van Marum, who charged large batteries by means of Galvanism.
PROPOSITION XIV.
_The muscular contractions, which, according to the observations of Galvani, are produced by an electric atmosphere whether natural or artificial, correspond entirely with those produced by the pile, or by similar kinds of apparatus._
When a change of equilibrium takes place in those systems of bodies which communicate with the nerves and the muscles of the animal machine, it is always sensible of this change, and muscular contractions are produced.
EXPERIMENT I.
It is curious to see an animal, placed at the extremity of an apartment, experience a shock, when the electric spark is extracted at a considerable distance. I performed this experiment several times in the _Cabinet de Physique_ of the Institute of Bologna, by means of a metal wire, not insulated, which was at the distance of four feet from the conductor of a common electrical machine. I repeated the experiment with crural nerves, having a ligature in the middle; and on extracting the spark, I observed violent contractions, which ceased when the ligature was formed at the place of their insertion into the muscles. I then performed with the new apparatus of Volta the experiments which Galvani had made with artificial electricity alone. At first I employed several glass cups and piles of from one to two hundred plates of metal; which proved to me that similar results might be obtained with the following simple apparatus.
EXPERIMENT II.
Having placed upon a table two glass vessels filled with salt water, (Plate II. fig. 5.) which I connected by means of an arc composed of brass and zinc, I applied to the surface of the water, in one of the vessels, the spinal marrow of a prepared frog, the corresponding muscles of which I held in one of my hands. Another person with his hand, or a plate of metal, then touched the water contained in the other vessel, and, at each contact, the muscles experienced violent contractions. To remove all idea of the contractions being produced by the action of the salt water, I connected with the spinal marrow a part of the muscles of another animal, which, instead of the spinal marrow, was made to touch the salt water, and obtained the same result.
EXPERIMENT III.
The same apparatus being retained, if either the person who touches the surface of the water in the first glass vessel, or the part of the frog immersed in the second, be insulated, no muscular contractions are produced; but they again take place when the insulation is removed. The violence of the contractions is increased by increasing the number of the glass vessels. If these vessels are made to communicate by means of arcs, formed of one homogeneous metal, the results are not different from those observed when heterogeneous metals are employed.
EXPERIMENT IV.
Being desirous to confirm the theory of the Galvanic atmosphere, I placed in it the body of an executed criminal. I removed the pile to the distance of a foot from the trunk, without the usual communication of metallic arcs; and having made an incision in each ancle, two persons held two frogs prepared in the usual manner, in such a position that the spinal marrow rested on the incisions. When matters were thus arranged, every time that a third person touched the summit of the pile, both the frogs experienced violent contractions, and to such a degree, that, leaving free one of the extremities, a real electrico-animal alarum was obtained, perfectly similar in its effect and identity to that described by Galvani in his Commentary. When the metallic apparatus is employed, if one of the persons who holds a frog be insulated, the frog will remain motionless, while the other will experience the usual effect. I had an opportunity of confirming the truth of this observation, on the trunk of a dog, during a course of experiments made in the _Hôpital de la Charité_, at Paris, and at St. Thomas’s Hospital, London.
PROPOSITION XV.
_Opium, cinchona, and other stimulants of a similar kind, which exercise a powerful action on the animal machine, contribute also to excite the action of the pile._
EXPERIMENT I.
In the last sitting of the Institute of Bologna, at which I was present, I constructed two piles, each composed of fifteen pieces of silver and zinc, employing for the one an extract of opium, and for the other an infusion of cinchona in alcohol. I covered the piles with two equal receivers; formed an insulated plenum, by pouring mercury around the bottoms of them; and placed weights on the receivers sufficient to prevent the mercury from raising them. At the end of some hours, I found a remarkable elevation of the surface of the mercury, so that the receivers remained fixed without requiring any weight to keep them down. In the bell which covered the pile where extract of opium had been employed, the mercury rose more than an inch; but in that covering the other, where cinchona had been used, the elevation of the mercury was scarcely three lines.
EXPERIMENT II.
Having successively introduced a taper into each of the two receivers before mentioned, it was immediately extinguished in that containing the pile with the extract of opium; but in the other containing the pile with the infusion of cinchona, it continued burning for some time. I found also that four of the plates, at the bottom of the pile where I employed opium, had suffered from the action of the mercury; and that some others, to the height of about three inches and a half, exhibited a few globules of that metal. The pile in which I employed infusion of cinchona showed scarcely any signs of the action of the mercury.
EXPERIMENT III.
As I concluded that the pile in which I had employed the alcoholic extract of opium possessed more activity than the other, I examined it for four or five days successively. I tried the flame of a taper with the same result as before, and assured myself that this pile retained the Galvanic power, though a little weakened, even till the eighth day. On the other hand, twenty-four hours had scarcely elapsed, when the pile in which alcohol and cinchona had been employed exhibited no signs of activity.
EXPERIMENT IV.
I constructed two piles, in the same manner, with pieces of pasteboard interposed, which had been previously moistened with strong solutions of camphor and of castor oil, in pure alcohol. In these two piles the Galvanic effects were much weaker in every respect than those observed in the preceding experiment; for, besides the explosion being less, the elevation of water in the insulated plenum was very small, and the alteration of the flame was scarcely sensible.
EXPERIMENT V.
I was able to convince myself that the effects of the two piles, before mentioned, were the immediate result of the substances dissolved, and not of the alcohol; for, having constructed a pile of thirty plates of silver and zinc, with pieces of pasteboard interposed, moistened with pure alcohol, I observed no signs of Galvanism; and the case was the same when I employed a pile of zinc combined with copper and other metals.
PROPOSITION XVI.
_If the general relation between Galvanism and electricity be examined, such a correspondence will be found between them, as tends to confirm the analogy already stated._
To illustrate this proposition, I shall here take a view of the particular properties of electricity and Galvanism, which, if considered separately, would not be sufficient for my object. I am, however, of opinion, that when combined together they will serve to prove it in a satisfactory manner.
1st, Galvanism, like artificial electricity, emits sparks, fuses metals, and can even be employed to charge armed non-conducting bodies. I have proved the last-mentioned property, discovered by the celebrated Van Marum, with a new apparatus, composed of a pile with a hole in the middle, in which I place the flask I intend to charge.
2dly, The influence of artificial electricity tends to accelerate the putrefaction of animal parts; and the same phænomenon may be produced by communication with the Voltaic pile, or by the first processes of Galvani.
3dly, The electricity of the Leyden jar is renewed in part immediately after its discharge. A similar phænomenon is exhibited by the pile; and it is observed, if the common Galvanic armatures be employed, that the vital force in animals is almost revived, when the arcs are applied different times.
4thly, As the action of common electricity and of the pile is suspended, when the combination of the metallic pieces is changed; in like manner, in a system of several animal machines, if their combination be changed, muscular contractions entirely cease.
5thly, Water may be decomposed by common electricity, as well as by the Galvanic pile, according to the ingenious method proposed by Dr. Wollaston. I lately saw, with the greatest pleasure, experiments on this subject performed by himself with the utmost neatness and precision. It is much to be wished, that the same result could be obtained by animal Galvanism alone; as it might tend to throw great light on some important points in physiology. For my part, I entertain no doubt that, after repeated trials, it may one day be effected, by means of large animals possessing a great abundance of animal electricity.
To conclude: I think I may venture to assert, that the correspondence between the properties of Galvanism and common electricity might be carried to a much greater extent, in confirmation of the analogy which I proposed to prove in this proposition.
PROPOSITION XVII.
_The hypothesis of an animal pile, analogous to that formed artificially, seems well calculated to explain the sensations and contractions in the animal machine._
It seems to be proved by the observations of Mr. Davy, Professor in the Royal Institution of Great Britain, and those of M. Gautherot at Paris, that a pile may be composed without any metallic substances whatever. We are therefore naturally led to suppose, that one may be composed also of animal substances alone. Though this has never yet been obtained by art, we behold it with admiration constructed by nature in various animals. If we examine, indeed, the structure of the regular bodies which succeed each other in the torpedo, the electrical eel of Surinam, and in the silurus, we shall find them to be real animal piles, differently arranged: and if an animal pile, exceedingly strong, be capable of communicating a shock, why should not one of a more moderate nature excite that activity which is necessary to produce muscular convulsions? I have already proved, that the system of the nerves and that of the muscles possess different Galvanic powers, or, as it were, different kinds of electricity, to which the animal moisture serves as a conductor. In this point of view, the discovery of the pile of the celebrated Volta, instead of destroying the principle of Galvanism, tends rather in a powerful manner to support it. The object of Galvani’s system is to prove the existence of an animal electricity, and then to explain how its action operates in producing muscular sensations and contractions. The first part of his system rests upon facts, the truth of which neither time, nor the different experiments made by philosophers, have been able to weaken. The second presents an hypothesis which, perhaps, may be further illustrated when the physiology of the human body is better known. Galvani, to explain the activity of animal electricity, supposes the nerves and muscles to be like the Leyden jar; and this idea I confidently adopted. But by the expression ‘Leyden flask’ he meant nothing else than that in the animal machine there are two opposite kinds of electricity, resulting from the nervous and the muscular systems, to which animal moisture continually serves as a vehicle. It was in this sense that he announced his theory of the Leyden flask, in his public lectures, and in his last works. No better comparison was then known, in the language of philosophy, to express this action. It however affords me great pleasure, that I can now substitute for it the pile discovered by Volta, which is perfectly consistent with the system of Galvani; and since I am ready to allow that the invention of the metallic pile gives Volta a title to the discovery of metallic electricity, I hope the discovery of animal electricity, properly so called, will be allowed to Galvani, as similar phænomena are exhibited by the nervous and muscular systems, independently of common electricity.
But some important questions in regard to Galvanism still remain to be answered, such as the following: whether the action of chemical combinations be the cause of Galvanism, or whether Galvanism be the cause of chemical combinations. In my opinion, we have not yet a sufficient number of data to determine this point. It may also be asked, whether Galvanism be of the same nature as electricity, but differently modified by the animal organization. For my part, until their identity be proved by further researches, I shall be contented with admitting that there is a great analogy between them.
But leaving these questions, the discussion of which might be premature, it will be better to deduce general corollaries from the series of experiments already detailed.
COROLLARY I.
It is found that there is a real attraction between certain parts of animals; and this tends to confirm the idea of a sort of atmosphere peculiar to parts of animals, as has been suggested by Humboldt. By these means it will perhaps be one day possible to explain, with less difficulty, the correspondence of some sensations in the animal machine.
COROLLARY II.
The action of Galvanism on the aëriform fluids may serve to explain its influence over the animal fluids by the oxidation of the humours, and other phænomena which hitherto have been explained only in a hypothetical manner.
COROLLARY III.
Fishes, and several amphibious animals which live under water, sometimes approach the surface on certain changes of the atmosphere. When the before-mentioned experiments on the Galvanic atmosphere are considered, we may easily explain, why those changes which take place in distant parts of the atmosphere are communicated to the element in which these animals reside.
COROLLARY IV.
It has been ascertained, that water saturated with salts, and in particular with muriate of soda, contributes a great deal to increase the effects of Galvanism. It is well known also, that fishes, as compared with other animals, possess a very high degree of vitality; and hence we have reason to admire the wisdom of nature in making the sea, which is destined for the abode of fishes, to be abundantly saturated with muriate of soda.
COROLLARY V.
As Galvanism possesses great activity in chemical decompositions, it cannot remain in a state of inaction; but must necessarily produce great changes in the animal fluids and functions.
COROLLARY VI.
This principle, to which some of the grand operations of nature have been entrusted, is not hypothetical; since it has been proved, that as there is a metallic arc and a metallic pile in the mineral kingdom, there is also an animal arc and an animal circle in the animal kingdom; which may one day throw great light on the progress of medicine, and be productive of considerable benefit to the human race.
PART THE SECOND.
ON THE INFLUENCE WHICH GALVANISM HAS ON THE VITAL POWERS.
To conduct an energetic fluid to the general seat of all impressions; to distribute its influence to the different parts of the nervous and muscular systems; to continue, revive, and, if I may be allowed the expression, to command the vital powers; such are the objects of my researches, and such the advantages which I purpose to derive from the action of Galvanism.
The discovery of the Galvanic pile by the celebrated Volta has served as a guide to enable me to obtain the most interesting results; and to these I have been conducted by numerous researches and a long series of experiments. I have examined the whole range of nature, and the grand family of animals has afforded me the means of making observations, highly interesting to physiology, on the whole œconomy of the vital powers. My experiments on this subject I shall divide into two Sections.
SECTION I.
_Galvanism applied to various quadrupeds, birds, and other warm-blooded animals._
EXPERIMENT I.
The head of an ox, recently killed, was subjected to the action of a pile (Plate II. fig. 1.) composed of fifty plates of copper and zinc, separated, as usual, by small pieces of pasteboard moistened with a solution of muriate of soda. Having moistened one of the ears with the same solution, by means of a syringe, I introduced into it one extremity of a metallic wire. I then formed an arc with this wire to the summit of the pile, and by means of another wire made a communication between the bottom of the pile and the nostrils. When this apparatus was applied, the eyes were seen to open, the ears to shake, the tongue to be agitated, and the nostrils to swell, in the same manner as those of the living animal, when irritated and desirous of combating another of the same species.
I then moistened both the ears with salt water, by the same method as before, and inserted into each an extremity of one of the arcs. When the Galvanism was communicated, the movements already described were reproduced; but they appeared to be much more violent.
EXPERIMENT II.
A pile composed of a hundred pieces of silver and zinc (Plate II. fig. 2.) being employed, the tongue issued from the mouth four inches, and re-entered it an inch, on each application of the arc; notwithstanding the resistance opposed by the teeth which pressed against it: so that after four or five applications of the arc it was entirely restored to its usual situation.
I repeated this curious experiment several times at Bologna and Turin, and lately at London before their Royal Highnesses the Prince of Wales, the Duke of York, the Duke of Clarence, and the Duke of Cumberland, who seemed to be much interested in my researches. I showed them that the tongue returned without being touched, merely by forming an arc between distant parts, such as the spinal marrow and the cervical or nasal muscles. A person who held the extremity of the tongue with a pair of pincers felt the effort it made to return every time that the Galvanism was applied.
EXPERIMENT III.
With the same apparatus I suspended from the extremity of the conducting arc the posterior half of a frog, by bending the iron wire at right angles into a small elbow; and then, instead of making the tongue touch the extremity of the arc, I brought it into contact with one of the paws of the frog, while the other extremity of the wire rested on the summit of the pile.
When this arrangement was made, I not only obtained the same contractions in the head of the ox, but I observed also that when the paw of the frog ceased to be in contact with the tongue, it was attracted by the latter, which produced in it oscillations, so that it formed a kind of Galvanometer; for the thighs of the small animal diverged more or less according to the intensity of the fluid which passed through them, and were restored to their former position when the paw of the frog and the tongue of the ox were again brought into contact. These oscillations continued about six minutes.
Suspecting, however, that the crural nerves might have some share in these phænomena, independently of the pile, I cut these nerves, and under similar conditions I obtained the same results.
EXPERIMENT IV.
Being desirous to repeat the above experiments on the heads of other oxen, and on those of sheep and lambs, varying the pile, both in regard to its nature and the number of pieces, I constructed three piles of twenty-five, fifty, and a hundred and twenty pieces of silver and zinc. The results, however, differed from the preceding only in the greater or less intensity of the contractions, according as one or the other apparatus was applied to the same animals. I remarked in particular, that the combination most favourable to muscular contractions is obtained, when the arc is established from the ears to the spinal marrow. In this case the eye is so much affected, that the eye-lids open entirely while the eye-ball turns round, and projects somewhat from its socket, as sometimes happens in the most violent madness.
EXPERIMENT V.
Having provided an ox recently killed, the head of which was not cut off, I formed an arc from one ear to the other, interposing the pile. The immediate result was a commotion so violent in all the extremities of the animal, that several of the spectators were much alarmed, and thought it prudent to retire to some distance. I then cut off the head, and formed an arc from the spinal marrow, first to the diaphragm, and then to the sphincter ani. In the first case, the diaphragm experienced violent contractions; in the other I obtained a very strong action on the rectum, which even produced an expulsion of the fæces.
EXPERIMENT VI.
To give more extent to my experiments, I thought proper to repeat them on lambs, chickens, and other warm-blooded animals; and without enumerating such phænomena as are common, I shall only observe, that the tongue, which was projected beyond the lips, again returned into the cavity of the mouth, after several applications of the arc, as was the case in the second experiment. The movements of the ears and eye-lids were stronger than in the other parts. Comparative anatomy must explain why this phænomenon, so striking in animals of this kind, is not observed in man.
EXPERIMENT VII.
The observations which I had made on the Galvanism of the pile excited my curiosity so much, that I was induced to try some comparative experiments by means of common electricity. With this view I placed an iron wire in each ear of a lamb, and discharged through it twice in succession a Leyden flask, the two coatings of which were in communication with the wires applied to the ears. By these means I obtained contractions, but weaker than those produced by the pile; and I always observed the same result in other warm-blooded animals.
EXPERIMENT VIII.
Having repeated the same experiments on live chickens, I found, to my great surprise, notwithstanding the weakness of their organization, that they sustained with firmness the strongest shocks, communicated several times, with a pile composed of fifty plates of silver and zinc. Though apparently dejected, and almost on the point of expiring,—as soon as I interrupted the action of the pile, they fluttered their wings, and seemed to congratulate themselves on their escape from danger.