Translated into English by “Google Translate” in June 30, 2020.
Bulletins of the Society of Anthropology of Paris, II ° Series. Volume 2, 1867.
pp. 600-617.
Polyzoism or animal plurality in man
By M. Durand (De Gros).
“Man, to know himself well, must know other animals. This is a truth now acquired, and before this meeting, more than anywhere else, it would be superfluous to demonstrate it. We all know that human organization is found in the organization of other species in the state of rudiments and fractions, - in the state of small change, so to speak; and thence the happy consequence that many anthropological problems, of which the elements are so complex and interdependent, which no direct analysis can overcome, suddenly resolve themselves, once brought back to the simple formulas of lower animality.
Thus the development of anthropology is linked by a close dependence on the development of comparative biology: we must therefore support its progress. Anthropologists, we must apply ourselves above all to rid it of its obstacles, so that our science can in turn take off.
And, indeed, the study of the diverse biological analogies which unite man to the rest of animals has advanced so far only by struggling against the shackles of prejudice. I want to talk about these pre-established opinions on the nature of our being, which, deeply implanted in our brains and in our hearts, in our mores, our institutions and the interests of life, oppose obstinate resistance when positive science, of which they had taken the place, one day comes to disturb them. These anthropological overperstitions, to which the scientist is hardly less subject than the ignorant and of which the rationalist philosopher is not always more free than the theologian, first of all fought the thought of bringing together all the lower forms of life between them to compare them to that which it takes on in us; then,
Nothing seems to us today more unreasonable, more manifestly contrary to logic and observation than to maintain, on the one hand, that our brain has for all purpose and any function to serve as an instrument for feeling and to the thought, and, on the other hand, that these faculties are absolutely foreign to the brain of the animal; while recognizing, however, that both brains, that all brains, are histologically, organologically and physiologically similar? And yet the “pure automatism of the beasts” has been professed by natural history as an axiom of the least questionable, until recently. This scientific prejudice could not be without consequence for the progress of anthropology. What was this consequence? It was, we guess, to shrink and curb the positive study of the mental man, by depriving this study of the more or less essential indications which it had to draw from the collateral study of the psychic facts offered by the other species. When Réaumur, breaking with the prevailing opinion, dared to inaugurate the experimental psychology of insects, he caused a scandal, and orthodox science hastened ‘to’ excommunicate it. “Imbecility!” this is the word Buffon used to characterize the work of this ingenious and daring innovator. Here again is the same judgment of the great naturalist philosopher, formulated in solemn terms: “A republic” of bees, he said, will never be, in the eyes of “reason, ” but a crowd of little beasts which n ‘have anything to do with us other than providing us with wax and ’honey’.
Science, thank God, has finally shaken off this shameful prejudice, and, after having been condemned as a mad and blasphemous error, comparative psychology is in honor today. But having freed himself from this crude prevention, has the biologist’s judgment therefore recovered all his freedom? No, of course, by other equally blind and more annoying prejudices, it also leads to it, and anthropology remains deprived of the most precious lessons which the discoveries of zoology hold for it in reserve. Didn’t the memorable debate on the origin of species attest to this situation? In this order of questions, at least, the prejudice did not speak alone, the discussion was able to seize it body to body and shake it; but, I’m coming to report to you, another point of comparative biology where this obscure influence reigns without question, where not an adversary has so far appeared to fight it. And yet this scientific point is not insignificant; I declare it one of the most important for the integral knowledge of the man; I do not know another which is held with more questions and interests.
As envisaged by a few scientists in the past, the true organization of invertebrates has been fully exposed by contemporary science. An immense fact, the significance of which was not first grasped, has been revealed; it was recognized that the animal of this category is not a simple and indivisible animal, but a compound, a meeting of distinct animals forming between them a kind of society of vital cooperation, and united to each other, according to the degree of organization of this set, by more or less close solidarity, by a more or less complicated and perfect systematic unity. Do you not see where such a discovery would lead if this surprising law of the organization of invertebrates, polyzoism, was going to spread, to vertebrates and to humans?... What! each of us would no longer be a simple person, but would represent a whole legion of real animated units, real individuals in the physiological and moral sense! Certainly such a novelty would upset the ideas of many, and we can safely say that all the most diverse or most contrary doctrines of which man is the subject, medicine, psychology, ethics, jurisprudence, theology, spiritualism, materialism and positivism, would have, for the first time, only one impulse and only one voice to protest.
Science, which had put itself so complaisantly in the service of Cartesian theodicy to the point of removing all - beasts from the faculty of wanting and feeling, science could not be more intractable towards a prejudice covered by the universal protection of all the teachings and of, all the beliefs. Natural history has therefore taken up the cause of the dogma of the indivisible and absolute unity of the human being; but, to protect this palladium against the disastrous revelations of the physiology of invertebrates, two different markets, two kinds of ingredients were chosen. Some have clearly understood that the constitutive polyzoism in animals without vertebrae being a proven fact, there remained only one way to save monozoism in man, it was to blow up the bridge that unites us to these lower tribes of the animal kingdom. Consequently, these naturalists have declared quite plainly that the vertebrate and the invertebrate are built on two totally distinct and dissimilar planes, and that the two organizations have nothing in common with each other. We will examine later the arguments which have been produced in support of this bold thesis.
The naturalists of the other school, proceeding in reverse of the first, began by establishing with particular care, with a real luxury of testimonies, and without seeming to be concerned with the consequences, that the series of vertebrates is only an extension direct from the invertebrate series; that the two types are basically similar; that both have zoonitism or polyzoism as their basis.
This broad concession made to scientific truth, only then did it appear to suspect the fatal blow which was to result from it for the dogma of monozoism. They seemed to want to change their mind; but, given the impossibility of retracting so much material evidence, so many decisive facts uncovered, an attempt was made to throw a cloud over these facts to conceal their meaning and significance.
The distinguished naturalist who occupies the chair of zoology at the Museum presented in the following terms the defense of the first of these two doctrines, which he rallied to following another of the most eminent French physiologist:
“It’s not just the nervous system, ” he says, “or the vertebra in its place, that clearly differentiates vertebrate animals from invertebrate animals”. In many respects, these differ entirely from the former. This separation, almost absolute, which aroused the obstinate criticisms of the naturalists of the so-called philosophical school; among which we see Geoffroy Saint-Hilaire, in France, Goethe and Oken, in Germany, asks to be established by some developments.
”One of the first notions to acquire, - continues the professor, - relates to the quite different distribution, in vertebrates and invertebrates, of this thing so mysterious in its very essence, cause according to some, effect according to others, which is called life.
“If we look at life as a cause, a principle of action having its origin in such or such point of the organism, and if we are allowed to represent, so to speak, life by a quantity which will be more or less great, according to the more or less great power also of the effect produced, we will say that, in invertebrates, life seems to be spread in equal quantities in all parts of the organism. In vertebrates, on the contrary, life is concentrated in a particular point of each individual, or at least in a very restricted part of his being.”
The professor continues: “If, he says, we want to see in life an effect, a result, we can express the principle that we want to state by saying that, in invertebrates, this result does not appear to be the consequence of the more particular action of such point of the organism, as it takes place in vertebrates, where, to use an expression a little too rigorous for such.. objects, the resultant seems to be applied to one or more organs special and distinct.
“An example will better illustrate the fact in question. Let us cut a paw to a dog; apart from the very local disturbance that the economy will experience, the animal can continue to live. If we continue the mutilation, we can perhaps push it far enough without life ceasing, but we always arrive at a point in the body such that, when it is reached, life suddenly disappears. This remarkable point, where life seems to concentrate, this vital knot, to use the expression of M. Flourens, is found in all vertebrates...” (Review of Scientific Courses, January 22, 1865.)
I do not have time here to follow in all its detours the demonstration you have just heard. I’ve had; moreover, opportunity to discuss it thoroughly elsewhere; I will confine myself to examining its principal point; in which, moreover, all the argument is summed up.
Vertebrates have a vital node, common and unique center of all the impulses of life; invertebrates have no vital knot. Life, among them; emanates from multiple foci or occurs uniformly throughout the entire substance of the organism. - This is the fundamental proposition of the doctrine. A few words will suffice, I hope, to expose the inanity of such a foundation.
We have been masterly told that a lesion or excision of a certain portion of the spinal bulb “leads to an abrupt disappearance from life. None of this exists, and one remains confused in the presence of such reckless inaccuracy. No, a thousand times no, the so-called vital node is not a single center of life; it is at most a center of pulmonary innervation. It is essential to life only because, and as much as, pulmonary respiration is itself essential to it; Here are the facts; made true this time, which, it seems to me, decides the question. The following passage is taken from the Treatise on Physiology by M. Longet:
”If the removal of the elongated medulla, ” says this professor, “can cause an immediate loss of life”. higher animal (mammal or bird); it is not the same, according to Brown-Séquard’s research; cold-blooded animals that also breathe through the skin. The lifespan can be counted per month for amphibians; per week, for a few reptiles; per day, for fish; then, by hours; for hibernating animals (during hibernation and using pulmonary insufflation); per minute, for birds and mammals.” (Treatise on Physiology, by Longet, t. II, p; 396.)
The vital knot, as a distinctive characteristic of a plan of organization and a mode of distribution of life which would be peculiar to vertebrates and which would separate them from invertebrates in a way, as we have said, almost absolute, is therefore only an expedient of the spirit of system, a fiction, a chimera, a fable; whose science is time to be disillusioned.
The polyzoïsme given as a general law of organization among invertebrate animals - and on this point everyone agrees; - a thought which must present itself at first sight to unprejudiced minds; is that the vertebrate probably differs from the invertebrate, as regards the fundamental plan of its structure, only in the way in which the invertebrate of higher species differentiates itself from the low level invertebrate, it is that is, by more complexity, specialization and unity in the societal mechanism of simple constituent or zoonite organisms. Now, this induction of analogy is confirmed by direct observation; and science, as long as it forgets its extra-scientific concerns to judge only on the facts, fully bears witness to this truth. This is what we will be able to ascertain with the help of a few quotes. I have borrowed them from various works, the authority of which cannot be disputed.
Here is first the judgment of your eminent and late colleague Gratiolet:
“The vertebrae, as everyone knows,” he said excellently, “are to the whole of the skeleton what the rings are to the body of the articulated; now, just as the definition of a cylinder is found in all the sections of this cylinder which are parallel to its base, so in a single vertebra is found the idea of the whole trunk; in a word, a vertebra is at the trunk what unity is to the number in a homogeneous concrete quantity.
“So,” he continues, “there are segments in the skeleton, there are segments, in the muscles”. The peripheral nerves in turn adapt to this segmentation, and observation shows that there are also segments in the central nervous system.
“This proposition is certain in the lower animals. In certain ringlets placed very low in the scale, sometimes each ring corresponds to a distinct ganglion (example: earthworm), sometimes there is only one ganglion for a determined number of rings (example: bdellian hirudinea).
“In most vertebrate animals, especially in the oviparous, an extended stem from head to tail replaces this chain of ringed. This rod, which encloses the spinal canal, is the spinal cord. There is certainly for each ring of the vertebral segment a certain part of this nervous rod; but is this part, this ideal segment, a real segment? Is there a central nervous ganglion for each vertebra? This is an important question from the point of view of philosophical anatomy and general physiology.
“Gall tried one of the first to solve it. He thought he had seen successive bulges in the medulla at the level of each vertebra. This proposition is especially very evident in the spinal cord of birds... M. de Blainville had accepted this opinion of Gall, to which the experiments of Legallois, Marshall Hall and Mueller seem to have given much strength; and, indeed, if we accept the ideas of these last two physiologists on the excito-motive force of the marrow, it seems that the division of the medullary axis into distinct segments necessarily follows.”
Thus expresses Gratiolet. His presentation, although very interesting, is too long to be reproduced here in full. I pass to its conclusion:
“It therefore seems to us, ” he says, “that each segment of the cord can be considered as a particular center of action, while admitting that on the occasion of the excitation of a segment, the modification is prolonged in the entire extent of the chain or nerve rod, in front of and behind the point that received excitement. So there is both multiplicity and unity in the nervous axis. “ (Gratiolet, Comp. Anatomy of the nervous system, t. II, p. 6.)
Now let’s consult Dr. Carpenter, the famous professor of physiology at the University of London:
“The brain and the spinal cord of the man,” he says, “in which ends the very great part of the afferent nerves, and from which almost all the motor nerves are born, can be regarded as formed by the agglomeration of a certain number of distinct ganglionic centers, each of which has its own attributions and is attached to nervous trunks which are particular to it. Beginning with the spinal cord, we find, by comparing it to the ganglionic chain of articulated animals, that it really consists of a series of ganglia arranged in a longitudinal line, and which are welded to each other, and each of which constitutes the center of the nervous circuit proper to any vertebral segment of the trunk.” (Manual of human Physiology.)
I crown these quotes with two particularly remarkable extracts borrowed from the excellent Lessons in general physiology of the nervous system of Professor Vulpian:
“Among the ringed, ” said this physiologist; each ganglion corresponds to a segment of the body often formed of several rings, as, for example, in the leech, of which all the parts are repeated from five to five rings. Each segment owned as well; in addition to its ganglion, a similar portion of the principal apparatus, even sometimes of the apparatus of the senses. This is the case with the polyophthalm, in which, as shown by M. de Quatrefages, each segment is provided with two rudimentary eyes which each receive from the corresponding ganglion a nervous net, a veritable optic nerve. These separate segments were named zoonites by Moquin-Tandon. This professor considered the animals of this branch as formed each of several elementary animals placed one after the other. This idea is very ingenious AND VERY TRUE. In the higher animals themselves, there is a vestige of this division in the spine.”
Here is the second passage:
“Another very constant fact, written elsewhere by the same author, is that, as Moquin-Tandon has pointed out; Dugès and others, each ganglion is an independent center of reflex action and coordinated, adapted actions. I have already quoted to you the experiences of Dugès on this point. We should never lose sight of this fact in general physiology. What is true here is also true for each segment of the spinal cord. The spinal cord, like the ganglionic chain of annelates, is a linear series of centers that are both independent and governed. Allow me to make this comparison: they are provinces with an autonomous administration, but subject, within certain limits, to a higher authority. “ (Vulpian, Lessons on the physiology of the nervous system, p. 787.)
The fundamental organizational similarity between vertebrates and invertebrates; the existence among the former, as among the latter, already zoonitic in constitution, cannot be recognized and affirmed in a more categorical manner than they have been by the authorized scholars whose declarations I have just reported. But after having proclaimed this gf and fact of general physiology and contributed for a considerable part to establish it in science, did they accept with firmness all the consequences? No, as I said above. There is one, and it is the main one, to which they all recoil; but in vain do they throw themselves into evasions to screen it out. To the clear and highly motivated professions of faith which precede, they added the following restrictive and attenuating comments,
Mr. Gratiolet first:
“However, ” he writes, following the passage so remarkable that we have given above, “we must recognize that by very clearly distinguishing excito-motor actions from those which have intelligence as their principle; that by thus following the law traced by M. Flourens, M. Marshall Hall has done a great service to science; indeed, the automaton is excited; IT DOESN’T FEEL POINT. EXCITABILITY belongs to the cord; SENSITIVITY depends on another device, the brain. “ (Gratiolet, Comparative anatomy of the nervous system, t. II. P. 6.)
I go to Mr. Carpenter:
“These abnormal reflex actions of the spinal cord of man, ” he writes in connection with a very interesting observation by Doctor W. Budd, “although sometimes powerful, have much less regularity and intentionality (purposiveness) which is apparent from the movements performed by the lower vertebrates (the frog, for example) after decapitation, or section of the marrow, which, in this respect, approximate the reflex movements of articulated animals. It should not however be concluded from this fact, - continues the author, - that there is no essential difference in the properties of the marrow between man and the lower animals, or that there is in play, in those -this, any psychic agent lacking in the first case. We have already seen that the most perfectly adapted combinations of muscular movements, all obviously tending towards a determined goal, do not necessarily imply by themselves that they are the result of a design or a voluntary choice on the part of the body that performs them; and, automatic, would be tantamount to attributing to the spinal cord the power to produce and regulate them with choice and conscience; Now, we have every reason to believe that such a power belongs exclusively to the upper parts of the cerebro-spinal centers. (Manual of human Physiology.)
Mr. Vulpian in turn formulates the strictness restriction, but with the accent of the most pronounced doubt, and less, it seems to me, to hide the truth from us than to make us glimpse it. Anyway, here is how it is expressed; these are the ganglia of the nerve chain of the ringlets:
“These lymph nodes, he says, are also the source of spontaneous movements, at least apparently; this is what you will see for yourselves by examining this crayfish, on which I have just practiced, a cross section of the ganglionic chain, at the level of one of the intervals which separate the rings from the abdomen. You see that the overall movements of swimming are abolished; the animal can no longer flex the abdomen suddenly, as it did before to throw itself back and forth. But you will still observe some movements from time to time in the false abdominal legs, spontaneous movements, at least in appearance, simultaneous, rhythmic, with normal characters. These movements are probably onlymechanical movements, provoked by contact with water or by irritation of the wound, and analogous to these movements of locomotion, spontaneous also in appearance, which are performed from time to time by the superior vertebrates from which the brain has been properly removed. said”. (Lessons on the general physics of the nervous system.)
We owe a great deal of gratitude to the scientists we have just heard for their masterful demonstration of zoonitism in the organism of the vertebra animal; We must therefore forgive them if, too concerned with the modesty of prejudice, they tried to cover with a shadow the nakedness of this truth so young and beautiful, which, thanks to their care, was given to us. But the moment has arrived when the scientific spirit wants to strip this virgin truth of all its veils to fertilize it.
The universality of zoonitism posed in principle, to prevent human polyzoism from ensuing, we try to maintain that, in vertebrates, and particularly in humans, the zoonite of the head is the only one that is animated, the only which possesses the sensitivity, the conscience, the will, and that all the other zoonites, although similar to the first in the triple histological, organological and functional aspect, are nevertheless only automata! What has been done to support this thesis? - Free and completely arbitrary assumptions, assertions devoid of any evidence and contrary to plausibility, conclusions in flagrant contradiction with the premises; nothing more.
The swimming movements performed by the middle zoonites of a crayfish from which the cerebro ganglion has been isolated, the movements that a decapitated frog makes with its legs to remove the forceps or the scalpel which injures it, are intentional and conscious only in appearance, it has been claimed. But is not appearance therefore not, in all cases, our unique criterion for observing the presence of an intimate state of sensation and volition outside of ourselves, outside of our own self? When I see here each of my colleagues performing acts which are apparently intelligent and voluntary, that is to say, which are analogous to the acts which, in my case, externally translate the intimate fact of wanting, feeling, thinking, I trust this appearance; I judge that, like me, my neighbor is a conscious being, sensitive and intelligent, - although such a judgment rests basically only on a pure induction of analogy and there is absolute impossibility of verifying it by direct observation; for it is only my feelings and my thoughts of which I can be aware, that is to say, of the existence of which I can obtain direct knowledge and true certainty.
And, in the present case, if the movements determined by the lower ganglionic centers of a crustacean, or by the spinal centers of an amphibian, have a purely mechanical nature and origin, why therefore the movements due to the impulse of the center are not these animals’ cephalic nerves purely mechanical movements also? The similarity alone testifies to the contrary! Why the whole crayfish, why the frog still in its integrity and moving by the combined impulse of its encephalic center and its spinal centers, why would they not be pure machines, as when they move under the isolated impulse of their secondary nervous centers? In a word, why not go back entirely to “pure automatism of the beasts”? It would be simpler and it would not be more irrational.
Yes, if the automation of so-called reflex movements is a truth, the automation of the whole beast is also a truth; and if the automatism of animals is only a lie, the automatism of the centers of the marrow is also a lie. The two automations are interdependent; both must be rejected or both admitted: there are no alternatives.
Physiology and medicine, psychology and morals have so far agreed to regard man as a living, feeling and thinking unit, entirely compact and irreducible, like, a single and simple animated body; and, on this first and common belief, all their dogmatic and practical institutions were formed. Now, new facts seem to come today to show us that this belief is a mistake; that the human being is, in reality, a collection of organisms, a collection of separate lives and of me, and that his apparent unity is entirely in the harmony of a hierarchical whole whose elements, brought together by close coordination and subordination, nevertheless carry, each in itself, all the essential attributes, all the primitive characters of the individual animal.
Such a principle is doubtless threatening to a whole vast system of established ideas and things; but let us follow it in its consequences, and we will be convinced that, if it comes to destroy, it also comes to build up, and that his work, all of positive truths, is preferable a thousand times over the scaffolding of illusions to which this work will be substituted.
If, later, the Society agrees to give me its attention again, I will outline before it some of the most interesting special applications of the law of polyzoism; but one must not expose oneself to renew the history of the golden tooth. So, before speculating on the applications of the new principle, let us first make sure that this principle exists, that it is founded in reason and in fact, In order to clarify this preliminary point, I came to put it to you; if I’m not mistaken, such a topic of discussion will be worthy of your interest and your insights.”
Mr. DALLY. “I listened with the most lively interest to the reading that M. Durand (de Gros) has just given us, and I believe that his ingenious views on the multiplicity of centers of vital action deserve the most serious meditations. Without being in a position to express an opinion on their accuracy, I seize the opportunity which presents itself to associate with me his criticisms relating to the abyss which, according to some naturalists, would separate invertebrates from vertebrates. The idea that the two branches are built on a different plane, while, obviously, the functions are the same, the organic elements identical, is based on this only difference that the devices are more or less perfected. Nervous system, circulation, digestion, locomotion, the two branches have everything in common and we can establish the most rigorous analogies between the devices, even though we would not have the amphioxus and its fossil counterparts; I therefore ask where is the abyss when we have the ganglionic chain and the cephalic ganglia of annellates, the vertebral canal of crustaceans and the pulmonary respiration of arachnids, etc., etc., to compare with the organic systems of vertebrates? It is high time to give up these supposed abysses, when everything shows us, even in the whole modern fauna, so incomplete, a series more or less regular, but incontestable.” the vertebral canal of crustaceans and the pulmonary respiration of arachnids, etc., etc., to be compared with the organic systems of vertebrates? It is high time to give up these supposed abysses, when everything shows us, even in the whole modern fauna, so incomplete, a series more or less regular, but incontestable. “ the vertebral canal of crustaceans and the pulmonary respiration of arachnids, etc., etc., to be compared with the organic systems of vertebrates? It is high time to give up these supposed abysses, when everything shows us, even in the whole modern fauna, so incomplete, a series more or less regular, but incontestable.”
Mr. ALIX. “Mr. Durand (de Gros), in the remarkable work which he read, quoted a passage from the book of Gratiolet, on the Comparative Anatomy of the nervous system, and he relied on this passage to affirm that there is type identity between vertebrate animals and invertebrate animals. This assertion is completely contrary to the teaching of Gratiolet, who wanted to show how one could, by an effort of the thought, bring back, these two types to. the same conception; but who has never thought of confusing them and making them drift from one another.
The meeting closed at six.
One of the secretaries: ALIX.
