CHAPTER III.VITALISM.
Its Extreme Forms—Early Vitalism, and Modern Neo-vitalism—Advantage of distinguishing between Soul and Life—§ 1.The Vitalism of Barthez—Its Extension—The Seat of the Vital Principle—The Vital Knot—The Vital Tripod—Decentralisation of the Vital Principle—§ 2.The Doctrine of Vital Properties—Galen, Van Helmont, Xavier Bichat, and Cuvier—Vital and Physical Properties antagonistic—§ 3.Scientific Neo-vitalism—Heidenhain—§ 4.Philosophical Neo-vitalism—Reinke.
Extreme Forms: Early Vitalism and Modern Neo-vitalism.—Contemporary neo-vitalism has weakened primitive vitalism in some important points. The latter made of the vital fact something quite specific, irreducible either to the phenomena of general physics or to those of thought. It absolutely isolated life, separating it above from the soul, and below from inanimate matter. This sequestration is nowadays much less rigorous. On the psychical side the barrier remains, but it is lowered on the material side. The neo-vitalists of to-day recognize that the laws of physics and chemistry are observed within, as well as without, the living body; the same natural forces intervene in both, only they are “otherwise directed.â€
The vital principle of early times was a kind of anthromorphic, pagan divinity. To Aristotle, this force, theanima,the Psyche, worked, so to speak, withhuman hands. According to the well-known expression, its situation in the human body corresponds to that of a pilot on a vessel, or to that of a sculptor or his assistant before the marble or clay. And, in fact, we have no other clear image of a cause external to the object. We have no other representation of a force external to matter than that which is offered by the craftsman making an object, or in general by the human being with his activity, free, or supposed to be free, and directed towards an end to be realized.
Personifications of this kind, the mythological entities, the imaginary beings, the ontological fictions, which ever filled the stage in the mind of our predecessors, have definitely disappeared; no longer have they a place in the scientific explanations of our time. The neo-vitalists replace them bythe idea of direction, which is another form of the same idea of finality. The series of second causes in the living being seems to be regulated in conformity with a plan, and directed with a view to carrying it out. The tendency which exists in every being to carry out this plan,—that is to say, the tendency towards its end,—gives the impulse that is necessary to carry it out. Neo-vitalists claim that vital force directs the phenomena which it does not produce, and which are in reality carried out by the general forces of physics and chemistry.
Thus, the directing impulse,considered as really active, is the last concession of modern vitalism. If we go further, and if we refuse to the directing idea executive power and efficient activity, the vital principle is weakened, and we abandon the doctrine. We can no longer invoke it. We cease to be vitalists if the part played by the vital principle is thus far restricted. At first it was both the author of theplan and the universal architect of the organic edifice; it is now only the architect directing his workmen, and they are physical and chemical agents. It is now reduced to the plan of the work, and even this plan has no objective existence; it is now only anidea. It has only a shadow of reality. To this it has been reduced by certain biologists. For this we may thank Claude Bernard; and he has thereby placed himself outside and beyond the weakest form of vitalism. He did not consider theidea of directionas a real principle. The connection of phenomena, their harmony, their conformity to a plan grasped by the intellect, their fitness for a purpose known to the intellect, are to him but a mental necessity, a metaphysical concept. The plan which is carried out has only a subjective existence; the directing force has no efficient virtue, no executive power; it does not emerge from the intellectual domain in which it took its rise, and does not “react on the phenomena which enabled the mind to create it.â€
It is between these two extreme incarnations of the vital principle, on the one hand an executive agent, on the other a simple directing plan, that the motley procession of vitalist doctrines passes on its way. At the point of departure we have a vital force, personified, acting, as we have stated, as if with human hands fashioning obedient matter; this is the pure and primitive form of the theory. At the other extreme we have a vital force which is now only a directing idea, without objective existence, and without an executive rôle; a mere concept by which the mind gathers together and conceives of a succession of physico-chemical phenomena. On this side we are brought into touch with monism.
The Reasons given by the Vitalists for distinguishing Soul from Life.—It is, in particular, on the opposite side, in the psychical world, that the early vitalists professed to entrench themselves. We have just seen that their doctrines were not so subtle as those of to-day; the vital principle to them was a real agent, and not an ideal plan in the process of being carried out. But they distinguished this spiritual principle from another co-existent with it in superior living beings—at any rate, in man: the thinking soul. They boldly distinguished between them, because the activity of the one is manifested by knowledge and volition, while on the contrary, the manifestations of the other for the most part escape both consciousness and volition.
In fact, we know nothing of what goes on in the normal state of our organs. Their perfect performance of their functions is translated to us solely by an obscure feeling of comfort. We do not feel the beating of the heart, the periodic dilations of the arteries, the movements of the lungs or intestine, the glands at their work of secretion, or the thousand reflex manifestations of our nervous system. The soul, which is conscious of itself, is nevertheless ignorant of all this vital movement, and is therefore external to it.
This is the view of all the philosophers of antiquity. Pythagoras distinguished the real soul, the thinking soul, theNous, the intelligent and immortal principle, characterized by the attributes of consciousness and volition, from the vital principle, thePsyche, which gives breath and animation to the body, and which is a soul of secondary majesty, active, transient, and mortal. Aristotle did the same. On the one side he placed the soul properly so called, theNousor intellect—that is to say, the understanding with itsrational intelligence; on the other side was the directing principle of life, the irrational and vegetative Psyche.
This distinction agrees with the fact of the diffusion of life. Life does not belong to the superior animals alone, and to the man in whom we can recognize a reasoning soul. It is extended to the vast multitude of humbler beings to which such lofty faculties cannot be attributed, the invertebrates, microscopic animals, and plants. The advantage is compensated for by the inconvenience of breaking down all continuity between the soul and life; a continuity which is the principle of the two other doctrines, animism and monism, and which is, we may say, the very aim and the unquestionable tendency of science.
As for classical philosophy, it satisfies the necessity of establishing the unity of the living being,—i.e., of bringing into harmony soul and body,—but in a manner which we need not here discuss. It attributes to the soul several modalities, several distinct powers: powers of the vegetative life, powers of the sensitive life, and powers of the intellectual life. And this other solution of the problem would be, in the opinion of M. Gardair, in complete agreement with the doctrines of St. Thomas Aquinas.
Vitalism reached its most perfect expression in the second half of the eighteenth century in the hands of the representatives of the Montpellier school—Bordeu, Grimaud, and Barthez. The last, in particular, contributed to the prevalence of the doctrine inmedical circles. A man of profound erudition, a collaborates with d’Alembert in theEncyclopædia, he exercised quite a preponderant influence on the medicine of his day. Stationed at Paris during part of his career, physician to the King and the Duke of Orleans, we may say that he supported his theories by every imaginable influence which might contribute to their success. In consequence of this, the medical schools taught that vital phenomena are the immediate effects of a force which has no analogues outside the living body. This conception reigned unchallenged up to the days of Bichat.
After Bichat, the vitalism of Barthez, more or less modified by the ideas of the celebrated anatomist, continued to hold its own in all the schools of Europe until about the middle of the nineteenth century. Johannes Müller, the founder of physiology in Germany, admitted, about 1833, the existence of a unique vital force “aware of all the secrets of the forces of physics and chemistry, but continually in conflict with them, as the supreme cause and regulator of all phenomena.†When death came, this principle disappeared and left no trace behind. One of the founders of biological chemistry, Justus Liebig, who died in 1873, shared these ideas. The celebrated botanist, Candolle, who lived up to 1893, taught at the beginning of his career that the vital force was one of the four forces ruling in nature, the other three being—attraction, affinity, and intellectual force. Flourens, in France, made the vital principle one of the five properties of forces residing in the nervous system. Another contemporary, Dressel, in 1883, endeavoured to bring back into fashion this rather primitive, monistic, and efficient vitalism.
The Seat of the Vital Principle.—Meanwhile, another question was asked with reference to this vital principle. It was a question of ascertaining its seat: or, in other words, of finding its place in the organism. Is it spread throughout the organism, or is it situated in some particular spot from which it acts upon every part of the body? Van Helmont, a celebrated scientist at the end of the sixteenth century, who was both physician and alchemist, gave the first and rather quaint solution of this difficulty. The vital principle, according to him, was situated in the stomach, or rather in the opening of the pylorus. It was theconcierge, so to speak, of the stomach. The Hebrew idea was more reasonable. The life was connected with the blood, and was circulated with it by means of all the veins of the organism. It escaped from a wound at the same time as the liquid blood. It is clear that in this belief we see why the Jews were forbidden to eat meat which had not been bled.
The Vital Knot.—In 1748 a doctor named Lorry found that a very small wound in a certain region of the spinal marrow brought on sudden death. The position of this remarkable point was ascertained in 1812 by Legallois, and more accurately still by Flourens in 1827. It is situated in the rachidian bulb, at the level of the junction of the neck and the head; or more precisely, on the floor of the fourth ventricle, near the origin of the eighth pair of cranial nerves. This is what was called thevital knot. Upon the integrity of this spot, which is no bigger than the head of a pin, depends the life of the animal. Those who believed in a localisation of the vital principle thought that they had found the seat desired; but for that to be so the destruction of thisspot must be irremediable, and must necessarily cause death. But if thevital knotbe destroyed, and respiration be artificially induced by means of a bellows, the animal resists: it continues to live. It is only the nervous stimulating mechanism of the respiratory movements which has been attacked in one of its essential parts.
Life, therefore, resides no more in this point than it does in the blood or in the stomach. Later experiment has shown that it resides everywhere, that each organ enjoys an independent life. Each part of the body is, to use Bordeu’s strong expression, “an animal in an animalâ€; or to adopt the phrase due to Bichat, “a particular machine within the general machine.â€
The Vital Tripod.—What then is life, or, in other words, what is the biological activity of the individual, of the animal, of man? It is clearly the sum total, or rather, the harmony of these partial lives of the different organs. But in this harmony it seems that there are certain instruments which dominate and sustain the others. There are some whose integrity is more necessary to the preservation of existence and health, and of which any lesion makes death more inevitable. They are the lungs, the heart, and the brain. Death always ensues, said the early doctors, if any one of these three organs be injured. Life depends, therefore, on them, as if upon a three-legged support. Hence the idea of thevital tripod. It is no longer a single seat for the vital principle, but a kind of throne on three-supports. Life is decentralized.
This was only the first step, very soon followed by many others, in the direction of vital decentralization. Experiment showed, in fact, that every organ separated from the body will continue to live if provided withthe proper conditions. And here, it is not only a question of inferior beings; of plants that are propagated by slips; of thehydrawhich Trembley cut into pieces, each of which generated a complete hydra; of thenaïswhich C. Bonnet cut up into sections, each of which reconstituted a complete annelid. There is no exception to the rule.
Decentralization of the Vital Principle.—The result is the same in the higher vertebrates, only the experiment is much more difficult. At the Physiological Congress of Turin in 1901, Locke showed the heart of a hare, extracted from the body of the animal, and beating for hours as energetically and as regularly as if it were in its place. He suspended it in the air of a room at the normal temperature, the sole condition being that it was irrigated with a liquid composed of certain constituents. The animal had been dead some time. More recently Kuliabko has shown in the same way the heart of a man still beating, although the man had been dead some eighteen hours. The same experiment is repeated in any physiological laboratory, in a much easier manner, with the heart of a tortoise. This organ, extracted from the body, fitted up with rubber tubes to represent its arteries and veins, and filled with the defibrinated blood of a horse or an ox taken from the slaughter-house, works for hours and days pumping the liquid blood into its rubber aorta, just as if it were pumping it into the living aorta.
But it is unnecessary to multiply examples. Every organ can be made to live for a longer or shorter period even though removed from its natural position; muscles, nerves, glands, and even the brain itself. Each organ, each tissue therefore enjoys an independent existence; it lives and works for itself. No doubt it shares in the activity of the whole, but it may be separated therefrom without being thereby placed in the category of dead substances. For each aliquot part of the organism there is a partial life and a partial death.
This decentralization of the vital activity is finally extended in complex beings from the organs to the tissues, and from the tissues to the anatomical elements—the cells. The idea of decentralization has given birth to the second form of vitalism, a softened down and weakened form—namely, pluri-vitalism, or the theory of vital properties.
The advocates of the theory of vital properties have cut up into fragments the monistic and indivisible guiding principle of Bordeu and Barthez. They have given it new currency—pluri-vitalism. This theory maintains the existence of spiritual powers of a lower order, which control phenomena more intimately than the vital principle did. These powers, less lofty in their dignity than the rational soul of the animists, or the soul of secondary majesty of the unitarian vitalists, are eventually incorporated in the living matter of which they will then be no longer more than the properties. Brought into closer connection therefore with the sensible world, they will be more in harmony with the spirit of research and with scientific progress.
The defect of the earlier conceptions, their common illusion, rose from their seeking the cause outside theobject, from their demanding an explanation of vital phenomena from a principle external to living, immaterial, and unsubstantial matter. Here this defect is less marked. The pluri-vitalists will in turn appeal to the vital properties as modes of activity, inherent in the living substance in which and by which they are manifested, and derived from the arrangement of the molecules of this substance—that is to say, from its organization. This is almost the conception of the present day.
But this progress will only be realized at the end of the evolution of the pluri-vitalist theory. At the outset this theory seems an exaggeration of its predecessor, and a still more exaggerated form of the mythological paganism with which it was reproached. The archeus, the blas, the properties, the spirits—all have at first the effect of the genii or of the gods imagined by the ancients to preside over natural phenomena, of Neptune stirring up the waters of the sea, and of Eolus unchaining the winds. These divinities of the ancient world, the nymphs, the dryads, and the sylvan gods, seem to be transported to the Middle Ages, to that age of argument, that philosophical period of the history of humanity, and there metamorphosed into occult causes, immaterial powers, and personified forces.
Galen.—The first of the pluri-vitalists was Galen, the physician of Marcus Aurelius, the celebrated author of an Encyclopædia of which the greater part has been lost, and of which the one book preserved held its own as the anatomical oracle and breviary throughout the Middle Ages. According to Galen the human machine is guided by three kinds of spirits:animal spirits, presiding over the activity ofthe nervous system;vital spiritsgoverning most of the other functions; and finally,natural spiritsregulating the liver and susceptible of incorporation in the blood. In the sixteenth century, in the time of Paracelsus, Galen’s spirits becameOlympic spirits. They still presided over the functional activity of the organs, the liver, heart, and brain, but they also existed in all the bodies of nature.
Van Helmont.—Finally, the theory was laid down by Van Helmont, physician, chemist, experimentalist, and philosopher, endowed with a rare and penetrating intellect. Here we find many profound truths combined with fantastic dreams. Refusing to admit the direct action of an immaterial agent, such as the soul, on inert matter, on the body, he filled up the abyss which separated them by creating a whole hierarchy of immaterial principles which played the part of mediators and executive agents. At the head of this hierarchy was placed the thinking and immortal soul; below was the sensitive and mortal soul, having for its minister theprincipal archeus, theaura vitalis, a kind of incorporeal agent, which is remarkably like the vital principle, and which had its seat at the orifice of the stomach. Below again were the subordinate agents, theblas, orvulcansplaced in each organ, and intelligently directing its mechanism like skillful workmen.
These chimerical ideas are not, however, so far astray as the theory of vital properties. When we see a muscle contract, we say that this phenomenon is due to a vital property—i.e., a property without any analogue in the physical world, namelycontractility, in the same way the nerve possesses two vital properties,excitabilityandconductibility, which Vulpianproposed to blend into one, calling itneurility. These are mere names, serving as a kind of shorthand; but to those who believe that there is something real in it, this something is not very far from theblasof Van Helmont.Vulcans, hidden in the muscle or the nerve, are here detected by attraction, there by the production and the propagation of the nervous influx; that is to say, by phenomena of which we as yet know no analogues in the physical world, but of which we cannot say that they do not exist.
X. Bichat and G. Cuvier: Vital and Physical Properties Antagonistic.—The archeus and the blas of Van Helmont were but a first rough outline of vital properties. Xavier Bichat, the founder of general anatomy, wearied of all these incorporeal entities, of these unsubstantial principles with which biology was encumbered, undertook to get rid of them by the methods of the physicist and the chemist. The physics and the chemistry of his day referred phenomenal manifestations to the properties of matter, gravity, capillarity, magnetism, etc. Bichat did the same. He referred vital manifestations to the properties of living tissues, if not, indeed, of living matter. Of these properties as yet but very few were known: the irritability described by Glisson, which is the excitability of current physiology; and the irritability of Haller, which is nothing but muscular contractility. Others had to be discovered.
There is no need to recall the mistake made by Bichat and followed by most scientific men of his time, such as Cuvier in France, and J. Müller in Germany, for the story has been told by Claude Bernard. His mistake was in considering the vital properties not only as distinct from physical propertiesbut even as opposed to them. The one preserve the body, the others tend to destroy it. They are always in conflict. Life is the victory of the one; death is the triumph of the other. Hence the celebrated definition given by Bichat: “Life is the sum total of functions which resist death,†or the definition of the Encyclopædia: “Life is the contrary of death.â€
Cuvier has illustrated this conception by a graphic picture. He represents a young woman in all the health and strength of youth suddenly stricken by death. The sculptural forms collapse and show the angularities of the bones; the eyes so lately sparkling become dull; the flesh tint gives place to a livid pallor; the graceful suppleness of the body is now rigidity, “and it will not be long before more horrible changes ensue; the flesh becomes blue, green, black, one part flows away in putrid poison, and another part evaporates in infectious emanations. Finally, nothing is left but saline or earthy mineral principles, all the rest has vanished.†Now, according to Cuvier, what has happened?
These alterations are the effect of external agents, air, humidity, and heat. They have acted on the corpse just as they used to act on the living being; but before death their assault had no effect, because it was repelled by the vital properties. Now that life has disappeared the assault is successful. We know now that external agents are not the cause of these disorders. They are caused by the microbes of putrefaction. It is againstthemthat the organs were struggling, and not against physical forces.
The mistake made by Bichat and Cuvier was inexcusable, even in their day. They were wrong not to attach the importance they deserved to Lavoisier’sresearches. He had asserted, apropos of animal heat and respiration, the identity of the action of physical agents in the living body and in the external world. On the other hand, Bichat, by a flash of genius, decentralized life, dispersing the vital properties in the tissues, or, as we should now say, in the living matter. It was from the comparison between the constitution and the properties of living matter and those of inanimate matter that light was to come.
We can now understand the nature of modern neo-vitalism. It borrows from its predecessor its fundamental principle—namely, the specificity of thevital fact. But this specificity is no longeressential, it is onlyformal. The difference between it and the physical fact grows less and almost vanishes. It consists of a diversity of mechanisms or executive agents. For example, digestion transforms the alimentary starch in the intestines into sugar; the chemist does the same in his laboratory, only he employs acids, while the organism employs special agents, ferments, in this case a diastase. It is a particular form of chemistry, but still it is a chemistry. That is how Claude Bernard looked at it. The vital fact was not fundamentally distinguished from the physico-chemical fact, but only in form.
This expurgated and accommodated vitalism (Claude Bernard pushed his concessions so far as to call his doctrine “physico-chemical vitalismâ€) was revived a few years ago by Chr. Bohr and Heidenhain.
Other biologists, instead of attributing the differencebetween the phenomena of the two orders to the manner of their occurrence, seem to admit the complete identity of the mechanisms. It is no longer then in itself, individually, that the vital act is particularized, but in the manner in which it is linked to others. The vital order is a series of physico-chemical acts realizing an ideal plan.
Neo-vitalism has therefore assumed two forms, one the more scientific and the other the more philosophical.
Chr. Bohr and Heidenhain.—Its scientific form was given to it by Chr. Bohr, an able physiologist at Copenhagen, and by Heidenhain, a professor at Breslau, who was one of the lights of contemporary German physiology. The course of their researches led these two experimentalists, working independently, to submit to fresh investigation the ideas of Lavoisier and those of Bichat, on the relation of physico-chemical forces to the vital forces.
It was by no means a question of a general inquiry, deliberately instituted with the object of discovering the part played respectively by physical and physiological factors in the performance of the various functions. Such an investigation would have taken several generations to complete. No; the question had only come up incidentally. Chr. Bohr had studied with the utmost care the gaseous exchanges which take place between the air and the blood in the lungs. The gaseous mixture and the liquid blood are face to face; they are separated by thin membrane formed of living cells. Will this membrane behave as an inert membrane deprived of vitality, and therefore obeying the physical laws of the diffusion of gases? Well! no. It does not so behave. The most carefulmeasurements of pressures and of solubilities leave no doubt in this respect. The living elements of the pulmonary membrane must therefore intervene in order to disturb the physical phenomenon. Things happen as if the exchanged gases were subjected not to a simple diffusion, a physical fact obeying certain rules, but to a real secretion, a physiological or vital phenomenon, obeying laws which are also fixed, but different from the former.
On the other hand, Heidenhain was led about the same time to analogous conclusions with respect to the liquid exchanges which take place within the tissues, between the liquids (lymphs) which bathe the blood-vessels externally and the blood which those vessels contain. The phenomenon is very important because it is the prologue of the actions of nutrition and assimilation. Here again, the two factors of exchange are brought into relation through a thin wall, the wall of the blood-vessel. The physical laws of diffusion, of osmosis, and of dialysis, enable us to foretell what would take place if the vitality of the elements of the wall did not intervene. Heidenhain thought he observed that things took place otherwise. The passage of the liquids is disturbed by the fact that the cellular elements are alive. It assumes the characteristics of a physiological act, and no longer those of a physical act. Let us add that the interpretation of these experiments is difficult, and it has given rise to controversies which still persist.
These two examples, around which others might be grouped, have led certain physiologists to diminish the importance of the physical factors in the functional activity of the living being to the advantage of thephysiological factors. It would therefore seem that the vital force, to use a rather questionable form of language, withdraws in a certain measure the organized being from the realm of physical forces—and this conclusion is one form of contemporary neo-vitalism.
Contemporary neo-vitalism has assumed another form, more philosophical than scientific, by which it is brought closer to vitalism, properly so called. We should like to mention the experiment of Reinke,[2]in Germany. Reinke is a botanist of distinction, who distinguishes the speculative from the positive domain of science, and cultivates both with success.
His ideas are analogous to those of A. Gautier, of Chevreul, and of Claude Bernard himself. He thinks, with these masters, that the mystery of life is not to be found in the nature of the forces that it brings into play, but in the direction that it gives them. All these thinkers are struck by the order and the direction impressed upon the phenomena which take place in the living being, by their interconnection, by their apparent adaptation to an end, by the kind of impression that they give of a plan which is being carried out. All these reflections lead Reinke to attach great weight to the idea of a “directing force.â€
The physico-chemical energies are no doubt the only ones which are manifested in the organized being, but they are directed as a blind man is by hisguide. It seems as if adoubleaccompanies them like a shadow. This intelligent guide of blind, material force is what Reinke calls adominant. Nothing could be more like the blas and the archeus of Van Helmont. Material energies would thus be paired off with their blas, their dominants, in the living organisms. In them there would therefore be two categories of force: “material forces,†or rather, material energies obeying the laws of universal energetics; and in the second place, intelligent “spiritual forces,†the dominants. When the sculptor is working his marble, in every blow which elicits a spark there is something more than the strong force of the hammer. There is thought, the volition of the artist, which is realizing a plan. In a machine there is more than machinery. Behind the wheels is the object which the author had in view when he adjusted them for a determined end. The energies spent in action are regulated by the adjustment—that is to say, by the dominants due to the intellect of the constructor.
Thus it is in the living machine. The dominants in this case are the guardians of the plan, the agents of the aim in view. Some regulate the functional activity of the living body, and some regulate its development and its construction. Such is the second form, the philosophical form, extreme and teleological, of contemporary neo-vitalism.