Popular Science Monthly/Volume 2/March 1873/Electricity and Life
|ELECTRICITY AND LIFE.|
TRANSLATED BY A. R. MACDONOUGH, ESQ.
GALVANI discovered, in 1794, that the muscles of animals experience contractions in contact with certain metals. In his view, this contact merely calls out the discharge of a fluid inherent in the animals themselves. The fact was not to be contested, but its explanation was. Lively discussions in the schools of physiology followed—fortunately, with a clear understanding that the difficulty could only be determined by experiments. A vast number were made, the name of Volta being connected with the most remarkable of them. Alexander Volta maintained, in opposition to Galvani, that the electricity which produces contractions in the muscles, far from originating in those organs, is introduced by the metals used in the process. In proof of this he constructed, in 1800, the pile that bears his name, and which is an arrangement in which the connection of two different metals becomes an abundant source of the electric fluid. Galvani and Volta were two men of distinguished genius, who thoroughly understood physics and physiology, and advanced nothing heedlessly. Their discoveries were the point of departure for one of the most admirable movements in all the history of science, a movement which is still most active, and is the more remarkable because it resulted but yesterday, as it were, in the complete demonstration that Galvani and Volta were both in the right. Science to-day proves that there is an electricity peculiar to animals, as Galvani declared. It decides also that electricity produced by external causes has an influence over animals, as Volta taught. From profound study of the two orders of phenomena, it deduces a system of procedure for the cure of very many maladies by electricity. Consequently, an exposition of the relations between electricity and life must begin with examining the electricity that exists naturally, in the same way that heat does in animals, and then go on to explain the action of the fluid on the organism, whether in a healthy or a morbid state. Such a description will complete what has been written in the Review respecting the relations of life with light and heat—relations that we may to-day consider as forming the features of a new science.
The most authentic witnesses to the existence of animal electricity are fish. The torpedo, the silurus, the gymnotus, the ray, and other fishes, develop spontaneously a more or less considerable quantity of electricity. This fluid, the production of which depends upon the animal's will, is identical with that of common electrical machines; it gives the like shocks and sparks at a certain tension. The apparatus for its formation consists of a series of small disks of a peculiar substance, kept apart by cells of laminated tissue. Fine nerve-end fibres are scattered over the surface of these disks, and the whole represents a sort of membranous pile, usually placed in the region of the head, sometimes toward the tail.
These fishes are the only animals provided with an apparatus specially devoted to the production of electricity; but all animals are electric, in this sense, that a certain quantity of that fluid is constantly forming within their organs. The existence of electricity peculiar to the nerves and muscles, and independent of their special modes of action, has been settled by numerous experiments, particularly by those of Nobili, Matteucci, and Dubois-Reymond. To prove the currents of nervous electricity, it is sufficient to prepare a frog's muscle, and touch it at two different points with the two ends of a nerve-filament of the same animal. The muscle then undergoes contraction under the influence of the nervous current. Another experiment, as simple, proves the existence of the muscular current. In an animal living or just killed, a muscle is exposed and cuts made in it perpendicularly to the course of the fleshy fibres, and communication effected by the two wires of a very sensitive galvanoscope between the natural surface of the muscle and the surface made by incision. The needle of the instrument then betrays the passage of a current. This muscular electricity may be obtained in tolerable quantity by placing a number of slices of muscle together in the form of a pile. The positive pole of the system will be the natural surface of one of the terminal slices, and the negative pole the cut surface of the other. Such a battery acts upon galvanic instruments, and can even excite contractions in other muscles.
Independent of these nervous and muscular electric currents, other sources of this fluid exist in the animal economy. Currents are produced between the outer and inner surfaces of the skin, in the blood, in the secreting vessels—in fine, almost throughout the whole organism. The experiments, as delicate as original, to which Becquerel has for several years devoted all the activity of his green old age, authorizes him now to assert the preponderance of electro-capillary phenomena in animal life. According to this accomplished physicist, two solutions of different nature, both conductors of electricity, separated by a membrane or a capillary space, compose an electro-chemic circuit; and, if we reflect on the anatomical elements of the various tissues, cells, tubes, globules, etc., in their connections with the fluids that moisten them, we find that they give rise to an infinite number of pairs constantly evolving electricity. The blood of the arteries with that of the veins forms a pair, having an electro-motive power of 0.57, that of a pair with nitric acid being 100. Becquerel explains, by the intervention of these currents, many physiological phenomena hitherto imperfectly understood. Granting the reality of such actions, yet it must be acknowledged that the general doctrine which combines them each with the other, and links the whole together with the various modes of action of the organism, is far from being clear and precise. We need to know how these currents are distributed and circulate, what lines and courses they follow. It is now time for experimental physiology to attack these difficult problems, the solution of which is absolutely necessary for accurate knowledge of vital determinations, that is, for the computation and the estimate of those various factors which are terms in all the equations of organic movement.
Vegetables, too, develop electricity. Pouillet has clearly demonstrated that vegetation throws it off. Other physicists, particularly Becquerel, have proved the existence of currents in the fruits, stems, roots, and leaves of plants. Becquerel took a branch of young poplar full of sap, introduced a platinum wire into the wood and another into the bark, and brought the two ends of the conductors together in a galvanoscope—the needle at once showed the passage of a current. Buff has lately made experiments, taking care not to injure the organs. Two vessels containing mercury receive platinum wires; over the mercury stood water containing the vegetables to be examined as to their electric condition. Taking the leaves and roots, Buff proved a current passing through the plant from the roots to the leaves; in a branch severed from the stem the current passed toward the leaves, too. To sum up, the existence of vital electricity is incontestable, though we do not yet precisely understand the conditions of this internal excitement, and know nothing of its true relations with the unity of physico-chemical operations in the living organism.
The latter are, at all events, exceedingly complex. There is in us, and in every organized being, an infinite world of the most various actions going on. The forces penetrating us are as manifold as the materials we are moulded from. In every point of our bodies, and at every moment of our existence, all the energies of Nature meet and unite. Yet, such order rules in the course of these wonderful workings, that harmonious blended action, instead of bewildering confusion, characterizes beings endowed with life. Every thing in them commands and answers, with balance and counterpoise. Buffon long ago felt and expressed this. "The animal," he said, "combines all the forces of Nature: his individuality is a centre to which every thing is referred, a point reflecting the whole universe, a world in little." A deep saying, coming from the great naturalist as the flash of an intuition of genius, rather than the result of rigid investigation—words which the movement of science confirms with ever stronger proofs, while borrowing from them light for its path.
Having determined that living bodies are in themselves sources of the electric fluid, we next inquire into the nature of the effects produced in the animal organism by electricity under different forms. The atmosphere contains a variable quantity of positive electricity; the earth itself is always charged with negative electricity. It is not yet precisely known how this diffused and silent force originates. Physicists suppose that it proceeds from vegetation and the evaporation of water. Becquerel has quite lately set forth a number of reasons, more or less plausible, for the belief that the chief part of atmospheric electricity is derived from the sun, and diffused by it into space together with light. Whether this be true or not, while the sky is clear this fluid has no visible effect on human beings; but, whenever it accumulates in the clouds, and gives rise to storms, it produces effects that are the most manifest proofs of the influence exerted over life by electricity. Persons killed by lightning present a great variety of appearances. Sometimes one struck by lightning is killed outright on the spot, the body remaining standing or sitting; sometimes, on the contrary, it is thrown to a great distance. Sometimes the flash tears off and destroys the victim's dress, leaving the body untouched, and sometimes the reverse is the case. In some instances the destruction is frightful, the heart is torn apart and the bones crushed; in others the organs are observed entirely uninjured. In certain cases flaccidity of the limbs occurs, softening of the bones, collapse of the lungs; in others, contractions and rigidity are remarked. Sometimes the body of the person struck decomposes rapidly, but at times it resists decay. Lightning, which shatters trees and overturns walls, seems not to produce mutilations in animals at all readily. When the stroke does not produce death, it creates at least serious disturbances—sometimes temporary, but oftener beyond remedy. Besides the burns and various eruptions noticed on the skin of those struck with lightning, they often suffer, very curiously, a complete loss of hair; they are affected with paralysis, dumbness, deafness, amaurosis, or imbecility. In brief, the destructive attacks of atmospheric electricity touch all the functions of the nervous system.
The action of electric fishes may be likened to that of lightning, in being independent of our intention. The shocks of the gymnotus are particularly formidable. Alexander Humboldt relates that, having put both his feet on one of these fish, just taken from the water, he experienced so violent a shock that he felt pains in all his joints the rest of the day. These shocks throw the strongest animals down, and it is necessary to avoid rivers frequented by the gymnotus, because, in attempting to ford them, horses or mules might be killed by the discharges. To capture these fish the Indians drive wild horses into the water, stirring the eels up out of the mud by their trampling. The yellowish livid creatures press against the horses under their bellies, throw down the greater part and kill some of them, but, exhausted in their turn, they are then easily taken with the aid of small harpoons. The savages employ them to cure paralysis. Faraday compares the shock of a gymnotus, which he had an opportunity to study, to that of a strong battery of fifteen jars. A live eel out of water, when touched by the hand, communicates a shock strong in proportion to the extent of surface in contact, and the stroke is felt up to the shoulder, and followed by a very unpleasant numbness. It may be transmitted through twenty persons in a chain, the first one touching the back, and the last the belly of the eel. The fishermen discover the presence of an eel in their nets by experiencing a shock in throwing pailfuls of water on, to wash them. Water is a good conductor, and this fish kills or benumbs the animals it feeds on by delivering a discharge through the water.
Other sources of electricity are known to exist, besides thunder-storms and fishes. Friction-machines, batteries, and induction instruments, yield three kinds of currents that act on vital functions, sometimes in a similar way, but oftener with marked differences, which have only recently been clearly distinguished. The action of static electricity, and that of electricity of induction, more sudden and violent, is particularly marked by mechanical effects so striking that they have long distracted experimenters from examining with due attention those effects of another sort, produced by the galvanic current. Yet, the latter in reality affects the animal tissues in a deeper way, and its resulting phenomena deserve the liveliest interest from a theoretical point of view, as well as from their applied uses.
Dutrochet proved, by remarkable experiments, that, when a tube closed below by a membrane, and containing gum-water, is placed in a vessel containing pure water, the level of the gum-water rises little by little through the gradual introduction of pure water into the tube, while a certain quantity of the gum-water inside mingles with the pure water outside. In a word, a mutual exchange takes place between these two fluids, communicating by the membrane, and the current, passing from the thinner liquid toward the denser one, is ascertained to be more rapid than that moving in the opposite direction.
This experiment reveals one of the most important phenomena of life in plants and animals, noted by the word endosmosis. Now, Dutrochet had before observed that if the positive pole of a battery be inserted in the pure water, and the negative pole in the gum-water, the acts of endosmosis are effected more energetically. Oniraus and Legros discovered further, that, if the contrary arrangement be adopted, that is, if the positive pole be placed in the gum-water, and the negative pole in the pure, the level of the liquid in the tube descends noticeably, instead of rising. Electricity, therefore, can reverse the usual laws of endosmosis. It exerts an influence not less distinct on all the other physico-chemical movements, taking place deep in the organs. In them it decomposes the salts, coagulates the albuminoid elements of the blood and the tissues, just as it does in the vessels of the laboratory. Take a very curious instance: In chemistry, on decomposing the iodide of potassium, iodine is freed, and betrays itself by the tinge of intense blue which it develops on contact with starch. Now, if an animal be injected with a solution of iodide of potassium, and then electrified, it is noticed, after a few minutes, that all the parts near the positive pole of the battery turn blue in presence of the starch, proving that they are impregnated with iodine. The iodide has been almost instantly decomposed, and the iodine carried by the current toward the positive pole.
It is not surprising, then, that the action of electricity influences the whole system of the nutritive operations. Onimus and Legros found that ascending continuous currents quicken the twofold movement of assimilation and diassimilation. Animals electrified under certain conditions throw off a greater proportion of urea and carbonic acid, proving a higher energy of the vital fire. On the other hand, if young individuals, in growing development, are subjected to the action of the current, they grow tall and large more quickly than in ordinary circumstances, furnishing the proof of an increase in the quantity of substances assimilated. To show how far vital phenomena are stimulated by electricity, we will cite another experiment made by Robin and Legros on noctilucæ. These are microscopic animals, which, when existing in great numbers in sea-water, render it almost as white as milk, and at certain times phosphorescent. Now, a current, directed into a vessel filled with such water, suffices to bring out a trace of light marking all its course. Electricity stimulates the phosphorescence of all the noctilucæ met on its passage between the two poles.
Interrupted currents, or currents of induction, contract the blood-vessels and slacken the circulation in almost every case: if they are intense, they even effect its complete check by a strong contraction of the little arterial branches. Continuous currents do not act in this way; usually they quicken the circulation, while occasioning an enlargement of the vessels, at least, this has been established by Robin and Hiffelsheim, in the microscopic examination of the flow of blood under electric stimulus. Onimus and Legros afterward proved that these movements are governed by the following law: The descending current dilates the vessels, and the ascending current contracts them. A striking experiment proves the value of this law: A part of the skull of a vigorous dog is removed, so as to expose the brain. The positive pole of a pretty strong battery is then placed on the exposed brain, and the negative pole on the neck. The slender and superficial vessels of the brain contract visibly, and the organ itself seems to collapse. Arranging the poles in the contrary order, the reverse is remarked; the capillary vessels swell and distend, while the substance of the brain protrudes through the opening made in the walls of the skull. This experiment proves the possibility of increasing or lessening at will the intensity of circulation in the brain, as indeed in any other organ, by means of electric currents. Onimus lately made an equally interesting experiment. Many persons know that the famous physiologist Helmholz introduced into medicine the use of a simple and convenient instrument called the ophthalmoscope, by means of which the bottom of the eye may be quite distinctly seen, that is to say, the net formed by the nerve-fibres, and the delicate vessels of the retina. Now, on examining this net, while the head is put under electric influence, the little blood-tubes are plainly seen to dilate and grow of a more lively crimson.
Let us now study the effect of the electric current on the functions of the motor system, and on sensibility. Aldini, a nephew of Galvani, undertook the first investigations of this kind upon human beings. Convinced that the proper study of the effects of electricity on the organs required the human body to be taken at the immediate instant after the extinction of life, he believed he would do well, as he relates himself, to take his place beside the scaffold, and under the axe of the law, to receive from the executioner's hand the blood-stained bodies which were the only really suitable subjects for his experiments. In January and February, 1802, he availed himself of the occasion of the beheading at Boulogne of two criminals, whom the government willingly gave up to his scientific inquiry. Subjected to electric action, these bodies presented so strange a sight as to terrify some of the assistants. The muscles of the face contracted in frightful grimaces. All the limbs were seized with violent convulsions. The bodies seemed to feel the first stir of resurrection, and an impulse to spring up. For several hours after decapitation, the vital centres of movement retained the power of answering to the electric excitement. At Glasgow, Ure made some equally noted experiments on the body of a criminal, which had remained on the gallows nearly an hour. One of the poles of a battery of 270 pairs having been connected with the spinal marrow, below the nape of the neck, and the other pole touching the heel, the leg, until then bent back, was forcibly thrown forward, almost oversetting one of the assistants, who had a strong hold on it. Placing one of the poles on the seventh rib, and the other on one of the nerves of the neck, the chest rose and fell, and the abdomen underwent the like motion, as in the act of breathing. On touching a nerve of the eyelid at the same time with the heel, the muscles of the face contracted, "rage, horror, despair, anguish, and fearful grins, combined in hideous expressions on the dead man's face." At the terrible sight one person fainted, and several were obliged to leave the room. Afterward, by exciting convulsive movements of the arms and fingers, the corpse was made to seem to point at one or another of the spectators.
Later researches have precisely fixed the conditions of this influence of electricity upon the muscles. Continuous currents, led directly to these organs, produce contractions at the moments of opening and of closing the circuits; but the shock produced on closing is always the strongest. While the continuous current is passing, the muscle remains persistently in a half-contracted state, as to the nature of which physiologists disagree. Influenced by excitements rapidly repeated and prolonged for a short time, the muscles assume a state of contraction and shortening, like that seen in tetanus. In this state, as Helmholz and Marey have shown, the muscle suffers a repetition of very slight shocks. Contraction is the result of the fusion of these elementary vibrations, indistinguishable by the eye, but capable of recognition and measurement by certain contrivances. Currents of induction produce more powerful contractions, but not lasting ones, which are succeeded, if electrization is prolonged, by corpse-like rigidity. Muscular contraction effected in such a case is attended by a local rise in temperature, proportioned to the force and length of the electric action. This increase of heat reaches its maximum, which may in some cases be four degrees, during the four or five minutes following the cessation of the electric impulse, and is due to the muscular contraction, which always gives rise to disengagement of heat.
The effect upon the nerves is very complex, and betrayed by movements and sensations very variable in intensity. Onimus and Legros state in general its fundamental laws thus: In acting on the nerves of motion, we see that the direct or descending current works more energetically than the other, with the reverse result on the nerves of sensation. The excitability of those nerves of a mixed kind is lessened by the direct and increased by the inverse current. This is true as to battery-currents, but currents of induction behave differently. While the sensation called out by the first is almost insignificant, the others, besides the permanent muscular contraction, produce a pain lasting as long as the nerve retains its excitability. The spinal marrow is one of the most active parts of the system. In the form of a thick, whitish cord, lodged inside the vertebral column, it constitutes a real prolongation of the brain, of which, under some circumstances, it takes the place. The unconscious depositary of a part of the force animating the limbs, by means of the nerves sent out from it, it transmits to them their direction and power to move, while the brain is unaware of its action. This takes place in what are called reflex motions, and these occur in beheaded animals, through the simple excitement, direct or indirect, of the spinal marrow. Experiments may be cited, showing the action of electricity on those phenomena which have their seat in the spinal marrow. If a frog is plunged into luke-warm water, at a temperature of 40°, it loses respiration, feeling, and motion, and would die if kept in it a long time. When taken out of the water, and placed in this state under the action of the current, it contracts strongly when its vertebral column is electrified by an ascending charge; but no motion follows if the descending current is applied. On the other hand, if the latter is sent into a beheaded animal, stimulated to reflex motions, by the excitement of the spine, it tends, as experiment shows, to paralyze these motions. In general, this is the law discovered by Onimus and Legros—the ascending battery-current, directed on the spine, increases the excitability of that organ, and consequently its power of producing reflex phenomena; the descending current, on the contrary, acts in the reverse way.
When the brain of animals is directly electrified, the modifications in circulation already spoken of result, but no special phenomena are observed. The animal shows no pain, and makes no movement, experiencing a tendency toward sleep, a sort of calm and stupor. Some physicians have gone so far as to propose electrization of the brain as a means of developing and perfecting the mental powers. Nothing hitherto justifies the belief that such a course could have the slightest influence for good over the functions of thought. On the contrary, it is very certain that the electric agent must be applied only with extreme caution to the regions of the head, and that it very easily occasions mischief in them. A strong current might readily cause rupture of the vessels, and dangerous hæmorrhage in consequence.
Again, electricity stimulates all the organs of sense. Directed upon the retina, it excites it, producing sensations of glare and dazzling. When sent through the organ of hearing, it produces there a peculiar buzzing noise, and, if brought in contact with the tongue, it calls forth a very characteristic metallic and styptic sensation. And in the olfactory mucous membrane it creates a sneezing irritation, and also, it seems, an odor of ammonia.
The currents not only act on the cerebro-spinal nerves, and the muscles concerned in life, as related outwardly, but affect also the parts of the nervous and muscular systems devoted to the functions of nutritive life. Electricity by induction, applied to these muscles, causes contraction in them at the point of contact with the poles, while the part situated between the poles remains without motion. Continuous currents produce, at the instant of closing the circuit, a local contraction at the junction with the poles, and then the organ becomes quiet; if it is previously in action, motion ceases. In the case of the intestine, for instance, peristaltic movement is checked; and by means of electricity contractions of the uterus may be suspended in an animal, during parturition. In general, the fluid suppresses spasms of all the involuntary muscles.
All these facts relating to electric action upon the muscles and nerves have been the occasion, particularly in Germany, of laborious investigations, with which are connected the names of Dubois-Reymond, Pflüger, and Remak. The doctrines of these learned physiologists, regarding the molecular condition of the nerves in their various modes of electrization, are still very much disputed. It must be said that they are not supported by any experimental certainty, and perhaps the ideas developed by Matteucci supply better means for the general solution of these difficulties. This eminent experimenter opposed, to the German theories about the electrotonic faculties of the nerves, certain evident phenomena of electrolysis, that is, of chemical decompositions effected by the currents. He supposed that the modifications of excitement in the nerves, brought about by the passage of electricity, depended on the acids and the alkalies resulting from the separation of the salts contained in animal tissues. To this first class of phenomena may be added those electro-capillary currents lately observed by Becquerel. Here must be sought the deeper causes of that complicated and as yet obscure mechanism of the strife between electricity and life.
The effects of electricity on plants have been much less studied, experiments made on this subject being neither accurate nor numerous enough. We know that electricity causes contractions in the various species of mimosa, particularly in the sensitive-plant, that it checks the flow of sap in certain plants, etc. Becquerel has studied its action on the germination and development of vegetables. Electricity decomposes the salts contained in the seed, conveying the acid elements to the positive pole, and the alkaline ones to the negative. Now, the former injure vegetation, while the latter benefit it. Quite lately, the same experimenter has made a series of researches upon the influence of electricity on vegetable colors. Employing strong discharges obtained from friction-machines, he has noticed very remarkable alterations of color, usually due to the rupture of the cells containing the coloring-matter of the petals. This matter, freed from its cellular covering, disappears on simply washing with water, and the flower becomes almost white. In leaves showing two surfaces of different shades, as the begonia discolor, a kind of mutual exchange of colors between the two surfaces has been noticed.
The physiological phenomena just spoken of are usually confounded in books with the facts of electric medical treatment, and it seems better to distinguish the two classes. The true method consists in first explaining the phenomena displayed in the healthy organism, as the only way of understanding afterward those that are peculiar to disorders. Electric treatment forms a group of methods to be classed among the most efficacious in medicine, provided they are applied by a practitioner well trained in the theory of his art. Indeed, the most thorough physiological knowledge is essential for the physician who would make the electric current serviceable. Mere experimenting, even the most sagacious, must here be barren of good results—a fact of which it is well to remind those who impute to the method itself the failures it meets with in unskilful hands. It is true that, since the days of Galvani and Volta, physicians have used galvanism in the treatment of many diseases. Early in the century, galvanic medicine was much talked of, and supposed to be the universal panacea. Galvanic societies, journals, and treatises, undertook to spread its usefulness. The fashion lasted a certain time, and would perhaps have grown indifferent, when the discovery of induced electricity, due to Faraday, in 1832, called professional attention once more to the virtues of the electric fluid, and led to a new and interesting range of experiments. Yet it is likely that the true systems of electric medical treatment, after the extraordinary illusions of their earlier days had vanished, would at length have sunk into disuse, had they not escaped from the ruts of empiricism. With its usual boldness, it had at first gained them a high rank, which it had no power to maintain. It was experimental physiology, with its exact analysis of the mechanical effects of this fluid upon the springs of the organism, which made its application in the healing art sure, true, and solid, as it now is. In this, as in all things, blind art has been the impulse to scientific research, which in turn steadily enlightens and perfects art.
It is singular that induction-currents have met with much better fortune than galvanic ones. The latter, the use of which introduced electric treatment, have gained real importance in physiology and medicine only within a few years, and after the reputation of induction-currents was well established, thanks chiefly to the efforts of Duchenne. A German physiologist and anatomist, Remak, who died six years ago, was the first to urge the singular remedial virtues of the voltaic current. Remak, after devoting twenty years to the study of the most difficult questions in embryology and histology, undertook, in 1854, the systematic examination and ascertainment of the action of continuous currents on the vital economy. He soon gained remarkable dexterity in dealing with, the electric agent, and detecting with the readiest insight the proper points for applying the battery-poles in each malady. Those who, with us, witnessed in 1864 his practice at the hospital, will remember it clearly. The methods of Duchenne were almost the only ones accepted in practice in France, till Remak came to prove to Paris physicians the powers of electrization by constant currents, in cases where Faraday's currents had been without effect. The teaching of the Berlin practitioner bore its fruits. A rising young physician, Hiffelsheim, was beginning to spread throughout Paris the use of the constant current as a healing agent, when death removed him in 1866, in the flower of his age. Another physician, who benefited by the lessons of Remak, Onimus, resumed the interrupted labors of Hiffelsheim, and is now busy in completing the system of the methods of electric medical practice, by subjecting them to an exact knowledge of electro-physiological laws. A few instances, from the mass of facts published on the subject, will serve to show how far the efficiency of these methods has actually been carried.
Experiment proves that, under certain conditions, the electric current contracts the vessels, and thus checks the flow of blood into the organs. Now, a great number of disorders are marked by too rapid a flow of blood, by what are known as congestions. Some forms of delirium and brain-excitement, as also many hallucinations of the different senses, are thus marked, and these are entirely cured by the application of the electric current to the head. No organ possesses a vascular system so delicate and complex as the brain's, nor is there any so sensitive to the action of causes that modify the circulation. For this reason, disorders seated in the brain are peculiarly amenable to electric treatment, and, when carefully applied, it is remedial in brain-fevers, mental delirium, headaches, and sleeplessness. Physicians who first employed the current were quite aware of this benign influence of the galvanic fluid over brain-disorders, and even had the idea of utilizing it in the treatment of insanity. Experiments in that direction have not been continued, but the facts published by Hiffelsheim justify the belief that they would not be barren. These facts testify to the benefits that electric currents (we mean only continuous ones) may some day yield in brain-diseases—a point worth the attention of physicians for the insane. Till lately it was thought that electricity was a powerful stimulant only, but what is true of interrupted currents is not true as to currents from the battery. Far from being always a stimulant, the latter may become in certain cases, as Hiffelsheim maintained, a sedative and calming agent. This control over circulation, joined with the electrolytic power of the galvanic current, allows its employment in the treatment of various kinds of congestions. A congested state of the lymphatic ganglia, the parotid glands, etc., may be relieved by this means, the current acting in such cases both on the contractility of the vessels, and the composition of the humors.
In cases of paralysis, more than any others, electricity displays all its healing power. Paralysis occurs whenever the motor nerves are separated from the nervous centres by any injuring cause, or by any modification of texture impairing their sensitiveness. With a destroyed nerve, paralysis is incurable, but, in case of its disease only, its functions can almost always be restored by electric treatment. As there is always some degree of muscular atrophy in the case, electricity is directed upon the nerves and the muscles at once, and the battery and the induction current usually employed together. As a rule, the first modifies the general nutrition, and restores nervous excitability, while the last stimulates the contractile power of the muscular fibres. The difference of action between the two kinds of currents is clear in certain paralyses, in which the muscles show no contraction under induction-currents, while under the influence of constant currents they contract better than the uninjured muscles. Experiments made some years ago in Robin's laboratory, on the bodies of criminals executed, proved that, after death, muscular contraction can still be produced by Volta's currents, though Faraday's current has no such effect.
When the motor nerves are in a state of morbid excitement, they compel either muscular contractions that are lasting, as tonic spasms, or intermittent ones. The different motor nerves most commonly excited are the facial nerves, the nervous branches of the forearm or the fingers, which are affected in "writer's cramp," and the branches of the spinal nerve, whose irritation occasions tic-douloureux, chronic wryneck, etc. Now, electricity cures, or at least noticeably benefits these different morbid states, and exerts the like influence over neuralgic and neuritic affections, wherever these disorders are not the symptoms of other deeper maladies. Currents restore the normal activity of nutrition in the diseased nerves, and the corresponding muscles; they act on rheumatism, too, in the most beneficial way, modifying the local circulation, quieting the pain, and stimulating reflex phenomena, which are followed by muscular contractions. Erb, Remak, Hiffelsheim, and Onimus, have proved beyond question this salutary action on swellings of the joints, either in acute or chronic cases.
The discoveries respecting the influence of electricity over the spinal marrow have been used with advantage in the treatment of such disorders as arise from unduly-excited activity in this organ, such as chorea, St. Vitus's dance, hysteria, and other nervous convulsions, more or less similar. We cite two instances of this sort published by Dr. Onimus, giving an idea of the mode of applying the current in such cases. A child, twelve years old, was seized with a frightful attack. Every five or six minutes it lost consciousness, rolled on the ground, its eyes turned upward, then grew so rigid that none of its limbs could be bent. The attack over, it regained its senses, but the least impression, at all vivid, sufficed to bring on a new attack. Ascending currents were first applied to the spinal marrow. The child was at once seized with a violent crisis. Descending currents were then used for fifteen days in succession, after which the little patient regained health. A young girl aged seventeen, in an hysteric condition, presented very strange symptoms in the larynx, the velum of the palate, and the facial muscles, among others a sort of barking, followed by vehement sniffing and horrible grimaces. By placing the positive pole in the patient's mouth against the arch of the palate, and the negative pole on the nape of the neck, all these morbid affections were completely subdued. The disposition of the poles in the reverse order, on the other hand, aggravated them. After sixteen repetitions of electric treatment, the young girl was almost completely cured, retaining only a muscular twitch of little importance, compared with her former ailments. Several cases of tetanus also were treated with complete success by similar methods. This terrible disease, the most fearful of all surgical complications, is due to an acute inflammation of the spinal marrow. It is followed by such an alteration of the motor nerves, that all the muscles of the body experience general contraction, and a painful rigidity that by degrees attacks the vitally essential organs. When an attack of this kind reaches the muscles of the chest and heart, death occurs, through asphyxia. In such a case the continuous current restores the motor nerves to their normal state. Two other chronic diseases of the spine, the first being particularly serious—progressive muscular atrophy and locomotive ataxy—often yield to the rational use of electricity, or at least are checked in their progress, the natural issue of which is death. It is worth remarking that these two disorders were discovered and described by Duchenne, in the course of his researches into this method of treatment. Electricity served his purposes of diagnosis, as it serves in physiology as a means of study, taking in that science the place of a kind of reactive agent, and revealing functional differences that no other process could have detected. To it alone, according to the way in which it affects a nerve or a muscle, belongs the power, under certain circumstances, of determining the nature and even the degree of alteration in nervous or muscular elements.
Aldini said that galvanism afforded a powerful means of restoring vitality when suspended by any cause. Several physicians, at the beginning of this century, restored life by this means to dogs, after they had undergone all the processes of drowning, and seemed dead. Halle and Sue proposed at that period to place galvanic machines in the different quarters of Paris, particularly near the Seine. This wise and useful plan has not yet been put into execution, though all experiments made since that time confirm the proof of the efficiency of electricity in cases of asphyxia and syncope, produced either by water or by poisonous gases. The galvanic current also restores respiration in cases of poisoning by ether or chloroform, even when recovery seems hopeless. Surgeons who understand this effect, remember it whenever chloroform seems dangerous to the patient under its influence.
Electricity is transformed into heat with great ease. If an intense current is passed through a very short metallic wire, it heats, reddens, and sometimes vaporizes it. This property has been taken advantage of by surgeons for the removal of various morbid excrescences. They introduce a metallic blade at the base of the tumors or polypi to be extirpated, and when this kind of electric knife becomes incandescent, under the influence of the galvanic current, they give it such a movement that the diseased part is separated by cauterization, as neatly as with a cutting instrument. This method, which avoids effusion of blood, and is attended by only slight pain, has yielded excellent results in the hands of Marshall, Middeldorpf, Sédillot, and Amussat. Besides this application, in which heat plays the chief part, electricity has been used to destroy tumors, by a kind of chemical disorganization of their tissue. Crusell, Ciniselli, and Nélaton, have made decisive experiments of this nature. Pétrequin, Broca, and others, suggest the same method to coagulate the blood contained in sacs, in aneurisms. If this novel surgery is not so widely known and used as it deserves to be, the reason is that the manipulation of electric instruments requires much practice and dexterity, and surgeons find the classic use of the scalpel more convenient.
This rapid historical view shows that the method of treatment by electricity is useful in very many diseases. Whether resorted to to modify the nutritive condition, to quicken or check circulation in the small vessels, to calm or excite the nerves, to relax or stimulate the muscles, to burn or detach tumors, electricity, if managed rationally, is destined to do distinguished service in the healing art. The range of treatment by heat is less considerable, yet of some extent. The examination of the medical value of treatment by light has scarcely begun, nor has much been done toward the study of weight or pressure, in their relations to medical science. At all events, there is now forming and gaining increased development, alongside of the medicinal use of bodies, a medicinal use of forces—besides the physic of drugs, a physic of powers. It is impossible to say at present which of the two will definitely prevail—more probably both will be called on to render valuable services to art.
The first savants who studied the action of galvanic electricity on dead bodies, and saw them recover motion, and even an appearance of sensation, supposed they had touched the secret of life, likening to the vital principle that other force which seems to warm again the frozen organs, and restore their springs. Slight reflection on the facts collected in the foregoing pages reveals the thorough illusiveness of such a hope. Not only is electricity far from being the whole of life, but it cannot even be regarded as one of the elements of life, or be compared, for instance, with nerve-force. In fact, the experiments of Helmholz have proved conclusively that such a comparison contradicts the truth. What is the peculiar sign of the vital forces and of vital unity, or the definite expression of their simultaneous action in one organism, is, precisely, organization. But electricity has no causal relation with organization proper. That is the work of some higher activity. That power in action, whatever it be, takes to itself all the forces of Nature, but it links them, coordinates them, and, fixing them into special conditions, compels their service to the purposes of life. Gravitation, heat, light, electricity, all these forces are maintained within living beings—only they are there disguised under a new phenomenal unity, just as the oxygen, hydrogen, carbon, nitrogen, and phosphorus, that make up a nerve-cell, vanish in it into a new unity of substance, without ceasing to exist in it as distinct chemical elements. The inorganic powers of Nature are as essential to life as lines and colors are in the composition of the painter's picture. What would the picture be without the painter's soul and labor? The picture is his peculiar work: the physico-chemical forces are the lines and colors of that homogeneous and harmonious composition, which is life. In it they would want meaning or power, if they did not in it, by the operation of a mysterious artist, undergo a transformation which raises them to a dignity not theirs before, and assigns their place in the supreme harmony. Thus, in the infinite solidarity of things, there is, as Leibnitz dreamed, a constant uprising of the lower toward the higher, a steady progress toward the best, a ceaseless aspiration toward a fuller and more conscious existence, an immortal growth toward perfection.—Revue des Deux Mondes.