THE HUMAN SPECIES.
I. The naturalist who meets with an object for the first time, instinctively asks the question:—What is this object? This question leads to another:—With what other objects shall I class it? To what group, and, in the first place, to what kingdom does it belong? Is it a mineral, a plant, or an animal?
The answer is not always easy. We know that, in what may be called the basis of each kingdom, there are ambiguous forms, whose nature has long been, and still is, the subject of contention among naturalists. We know that polyps were long regarded as plants, and that nullipores, at first taken for polyps, are now divided between the vegetable and mineral kingdoms; and, finally, we know that even now, botanists and zoologists dispute over certain diatoms and transfer them from one kingdom to the other.
Similarly the question has been asked:—What is man? and it has been answered from several points of view. To the naturalist it has but one meaning, and signifies, in which kingdom must man be placed? or better: is man an animal?
In spite of all the differences which a comparison of man with the mammalia presents, should he be classed with them? This question is similar to that which Peysonnel is said to have asked himself, when, struck by the special phenomena presented by the coral, he asked himself whether the object before him was a vegetable.
It is evident that, in order to solve the first problem which arises from a study of the natural history of man, we must have a clear idea what are these great groups of beings, which are called kingdoms; we must give an account of the characters which distinguish and separate them from each other, and then of their true scientific meaning. It will be sufficient for the purpose to explain the well-known laws of Linnæus, supplementing the theory of the immortal Swede by some ideas borrowed from Pallas and de Candolle, and by one of the fundamental conceptions which Adamson and A. L. de Jussieu have almost equally contributed to introduce into science.
II. It is impossible for anyone, whether learned or otherwise, not to recognise at once the difference between two kinds of objects very distinct from each other: inanimate bodies and organised beings. These are the two groups into which Pallas has divided kingdoms under the name of empires. Their distinction is generally easy, and I shall confine myself to recalling some of the most essential differences.
Inanimate bodies, when placed under favourable circumstances, last for an indefinite time, neither taking nor giving anything to the surrounding world; organised beings, under whatever conditions they are placed, only last for a fixed period of time, and, during this existence, undergo every moment losses of substance which they repair by means of materials taken from without. Inanimate bodies, even when they assume the fixed and definite form of crystals, are formed independently of all other bodies resembling them; they have from their commencement fixed forms, and increase simply by superposition of new layers. Every organised being is connected either directly or indirectlywith a similar being, in the interior of which it first appeared in the form of a germ, then grew and acquired its definite form by intussusception.
In other words, filiation, nutrition, birth and death, are so many characteristics of the organised being, of which no trace is found in inanimate bodies. I agree with Pallas in making inanimate bodies compose the Inorganic Empire, and organised beings the Organic Empire.
I must here make an observation, the importance of which will be easily understood.
The existence of the two groups which have been recognised by the good sense of the general public as well as by the science of Pallas, is a fact absolutely independent of all hypothesis. Whatever explanation we may propose to account for the differential phenomena which distinguish them, these phenomena will not the less exist; the inanimate body will never be an organised being.
To attempt, under any pretext whatever, to reconcile or confound these two kinds of objects with each other, is to go in direct opposition to all the progress made for more than a century, and especially during the last few years, in physics, chemistry and physiology. It is inexplicable to me that some men, whose merits I otherwise acknowledge, should have recently again compared crystals to the simplest living forms, to the sarcodic organisms, as they were called by Dujardin, who discovered them, and was the first to give a comprehensive theory of them from minute observations. A change of name is useless; the things remain the same, and protoplasm has the same properties as sarcode. The animals, whose entire substance they seem to form, have not altered their nature; whether monera or amœbæ, these forms are the antipodes of the crystal from every point of view.
A crystal, as M. Naudin has well remarked, closely resembles one of those regular piles of shot which may be seen in every arsenal. It only increases from the exterior, as the pile is increased when the soldier adds a fresh layer of shot;its molecules are just as immovable as the balls of iron. It is exactly the contrary with the organised being, and the simpler its composition the greater the contrast. The small size of the moneron and the amœba prevents, it is true, certain observations. I appeal, however, to all those naturalists who have studied certain marine sponges in a living state. They must like myself have remarked the strange activity of thevital whirlpoolin the semi-sarcodic substance which surrounds their siliceous or horny skeleton; they will have seen the sea water in which they are placed move with a rapidity which it never exhibits when in contact with any other animal.
The reason is that, in the organised being, the repose of the crystal is replaced by an incessant movement; that, instead of remaining immovable and unalterable, the molecules are unceasingly undergoing transformation, changing their composition, producing fresh substances, retaining some and rejecting others. Far from resembling a pile of shot, the organised being may much rather be compared to the combination of a number of physico-chemical apparatus, constantly in action to burn or reduce materials borrowed from without, and ever making use of their own substance for its incessant renewal.
In other words, in the crystal once formed the forces remain in a state ofstable equilibrium, which is only interrupted by the influence of exterior causes. Hence the possibility of its indefinite continuance without any change either of its forms or of its properties. In the organised being the equilibrium isunstable, or rather, there is no equilibrium properly so called. Every moment the organised being expends as muchforceasmatter, and owes its continuance solely to thebalance of the gain and loss. Hence the possibility of a modification of its properties and form without its ceasing to exist.
Such are the bare facts which rest upon no hypothesis whatever; and how can we, in the presence of these facts, compare the crystal which grows in a saline solution to the germ whichbecomes in succession embryo, fœtus, and finally a complete animal? How can we confuse theinanimate bodywith theorganised being.
The two groups are easily separated by the phenomena they exhibit. It is the same with the causes of the phenomenon.
Naturalists and physiologists are here divided. Some would have it that the cause, or the causes, are identical, and that conditions, which are almost accidental, alone determine the difference in the results by changing their mode of action. In their opinion the formation of a crystal or of a moneron is only a question of resultant.
Others consider living beings as the result of a cause entirely different from those which act in inanimate bodies, and refer to this cause alone everything which takes place in these beings.
These two methods appear to me, from the exclusive element in each, to be equally ill-founded. It cannot be denied that phenomena identical with those characteristic of inanimate bodies are found in organised beings, and we have, therefore, no scientific reason to attribute them to different causes.
But organised beings have also their special phenomena radically distinct from, or even opposed to, the former. Is it possible to refer all of them to one, or to several, identical causes? I think not. For this reason, I admit with a great number of eminent men of every age and country, and, I believe, with the majority of those that respect modern science, that organised beings owe their distinctive characteristics to aSpecial Cause, to aSpecial Force, toLife, which in them is associated with the inorganic forces. For this reason I consider it legitimate to call themLiving Beings.
I shall often, however, return to this class of considerations, in order to make it quite clear in what sense I take these words,Force, andLife.
III. The two Empires of Pallas are themselves sub-dividedinto Kingdoms, which are characterised by special facts and phenomena, becoming more and more complicated as we ascend the scale of nature.
And, in the first place, I distinctly admit with de Candolle the existence of aSidereal Kingdom. To any one who considers, as far as we are able, the little that we know of the universe, the celestial bodies, suns, planets, and comets or satellites only appear as molecules of the great All which fills indefinite Space. One general phenomenon which is unchangeable, however varied in its forms, is, as it were, the attribute of these bodies. All, whether gaseous or solid, obscure or luminous, hot or cold, move within curves of the same nature, obeying the laws discovered by Kepler. It is now well known thatfixed starsdo not exist.
In order to explain thisphenomenonphilosophers have admitted the existence of aforcewhich they have calledGravitation, the effect of which is to precipitate the stars towards one another, as if they mutually attracted each other, whilst obeying the laws of Newton. Now it is well known that the great Englishman himself gave no opinion upon the mode of action of this force, and that he hesitated between the hypothesis ofAttractionand that ofImpulsion. The first should prevail as being more in accordance with the immediate results of observation; but the second also has had serious partisans, among whom I will only mention M. de Tessan.
Thus Newton, in spite of all his genius, cannot tell us what was the cause of the movement of the stars; he was not even able to determine the immediate mode of action of this cause; and yet there is not a scientific term more universally received than that ofGravitation, there is not a case in which the expressionForceis more generally accepted. The reason of this is, that in the presence of general facts and groups of phenomena, it is necessary to make use of terms as simple as possible. We must, however, avoid the delusion of thinking thatnamingis equivalent toexplaining.
In cases analogous to that of which we have been treating, the word Force merely indicates the presence of anUnknown Cause, which gives rise to agroup of fixed phenomena. In assigning names to each of the Forces or Unknown Causes to which we consider ourselves able to refer certain groups of phenomena, we facilitate the demonstration and discussion of the facts. The scientific man knows very well that he cannot go beyond this.
It is in this sense, and in this sense alone, that I have used above the expressionsForceandLife. Astronomers consider gravitation the unknown cause of the movement of the stars; I consider Life as the unknown cause of the phenomena which are characteristic of organised beings. It may be that both gravitation and Life, as well as the other general forces are merely asx, of which the equation has not yet been discovered. I shall presently return to these considerations.
Be this as it may, whatever our real ignorance, whatever the Cause of which we are here treating, and thoughImpulsionshould one day replaceAttractionin our Theories, the facts would still remain the same. The stars would still be distributed through space, and subject to the laws of Newton and Kepler; they would still constitute a perfectly distinct whole, in the part assigned to the bodies which compose it, and in the nature of the relations which unite them. They would still form theSidereal Kingdom.
This kingdom is then characterised by ageneral phenomenon, theKeplerian Movement, which may be attributed to a single force, namely that ofgravitation.
IV. Let us now return to the Earth, the only celestial body which we can study in detail. Modern discoveries, however, judging from the relation of the elements and their mutual action, make it almost certain that the greatest similarity exists between the stars distributed in space, between all those at least which form part of our heavens.
Let us first establish the fact that upon our globe we again meet with the Keplerian Movement in falling bodies.Attraction is here represented byWeight. Gravitation reappears with all its laws, acting upon grains of dust as it acts upon worlds. The parts of the whole, of cosmos, as Humboldt would have said, cannot escape from the force which governs the whole.
But upon the surface of our Earth and in its interior, as far as we have been able to penetrate either by direct observation or scientific induction, we notice the appearance of other movements which are not subject to the laws of Kepler or Newton; phenomena appear which are entirely new and perfectly distinct from those due to gravitation. They are thephysico-chemicalphenomena. From their number and their difference in character they were long attributed to the action of distinct forces which were calledElectricity,Heat,Magnetism, etc. Modern science, however, by transforming, so to speak, one into the other, has demonstrated their original unity. Physicists refer them all to nothing more than so many manifestations of the undulations of ether. The vibration of the latter is then the fundamental phenomenon from which all the others rise.
But this ether is absolutely hypothetical; its nature is perfectly unknown; no one knowing whence it acquires this quantity of movement, which, according to actual theory, should be subject neither to increase nor diminution. Now, in reality, we have here theUnknown causeof all physico-chemical phenomena. For this reason, and also for convenience, we shall give a name to this unknown cause, to thisforce, and call itEtherodynamy(Ethérodynamie).
But is not Etherodynamy only a particular form, a simple modification, or an effect of gravitation? Are not these two forces only different manifestations of a more general force? Many eminent men are much inclined to admit one or other of these hypotheses. Still, up to the present time, the facts do not seem to me to shew much agreement with them. Etherodynamy is displayed even in space and among the stars by variable, localised and temporary phenomena; the action of gravitation is one, universal andconstant. Man has always been able to exercise a certain amount of control over the former; he can produce at will light and heat; modern science cannot act upon the second. We can neither augment nor diminish, reflect or refract, or polarise weight; we cannot arrest its action. Even in the fall of bodies the regularity in the acceleration of the motion proves that the cause of this movement is subject to no alteration. Here then is notransmutation of forcesimilar to that in a machine worked by electricity or heat.
But whatever be the progress of science, and though M. de Tessan’s theory should be confirmed by experiment, the difference between the phenomena would not be diminished; the conclusions to be drawn from the facts in connection with the question we are here discussing would remain the same.
It is scarcely necessary to remark that the physico-chemical phenomena produced by etherodynamy can act upon masses or be exclusively molecular. They are in all cases similar to those which depend upon gravitation, they are subject to invariable laws and are always repeated in a similar manner when produced under similar circumstances.
No antagonism, it is true, exists between gravitation and etherodynamy. It is no less true that the action of the first is always disturbed in a peculiar manner by that of the second, and that in some phenomena it seems as if the latter would neutralise the former. This fact is most strikingly shown in some of the commonest experiments in physics. The gold leaves of the electroscope separate, the pith-balls are attracted towards electrified bodies in spite of their weight, and are repelled with a rapidity greater than that which would result merely from their own weight. And yet these bodies have no more ceased to possess weight than those masses of iron raised by the powerful magnets of M. Jamin. Etherodynamy in these two cases merely overcame gravitation and either modified or imitated its action.
Those terrestrial bodies which present no other phenomena than those which can be referred to either gravitation or etherodynamy have, since the time of Linnæus, been termedInanimate Bodies. Together they constitute theMineral Kingdom. We see that the existence and the distinction of this group are perfectly independent of any hypothesis intended to explain the phenomena.
Two kinds of phenomenathen are characteristic of the mineral kingdom:phenomena of the Keplerian movementandphysico-chemical phenomena, which may be attributed to the action of two forces:gravitationandetherodynamy.
V. The sidereal and mineral kingdoms form the Inorganic Empire. Passing from it we enter the domain of organized and living beings. We have already seen the essential phenomena by which they are distinguished. These phenomena differ essentially from all those which we have observed in inanimate bodies. It seems to me, therefore, necessary to attribute them to a special cause,—toLife.
I know that in the present day any one making use of this word is readily accused by a great number of physicists and chemists, and by an entire physiological school, of introducing into science a vague and almost mysterious expression. There is, however, nothing in it more vague or mysterious than in the wordgravitation.
It is very true that we do not knowwhatLifeis; but no more do we knowwhatthe forceisthat set the stars in motion and retains them in their orbits. If astronomers have been right in giving to theforce, orunknown cause, which gives the worlds their mathematical movements, naturalists have a perfect right to designate by a special term thatunknown causewhich produces filiation, birth and death.
It will be apparent that my idea of Life is not the same as it was with many ancient vitalists, that it is no more thearcheof van Helmont than thevital principleof Barthez. Its function appears to me very different to that attributedto it by most of our predecessors, and which is still attributed to it by some physiologists.
Far from merely animating the organs, it is closely associated with the forces of which we have already spoken. Living beings are heavy, and therefore subject to gravitation; they are the seat of numerous and various physico-chemical phenomena which are indispensable to their existence and which must be referred to the action of etherodynamy. But these phenomena are here manifested under the influence ofanother force. It is for this reason that the results of these phenomena are often quite different to those in inanimate bodies, and that living beings have their special products. Life is not antagonistic to the inanimate forces, but it governs and rules their action by its laws. Therefore it makes them produce tissues, organs and individuals instead of crystals; it organizes germs, and maintains through space and time, in spite of the most complex metamorphoses, thatunity of definite living formswhich we callSpecies.
If the anti-vitalists would only seriously reflect upon the matter, they would acknowledge that, considered from this point of view, there is nothing more mysterious in living beings than in some of the commonest phenomena presented by inanimate bodies. The intervention of Life as a modifying agent of actions purely etherodynamic may be as easily admitted as that of etherodynamy itself modifying and overcoming the action of weight. It is just as strange to see a piece of iron attracted and supported by a magnet, as to see carbon, oxygen, hydrogen and nitrogen combine and dispose themselves so as to form an animal or vegetable cell instead of any imaginable inorganic composition.
I have repeatedly, and for many years, maintained the doctrine which I have summed up here. It seems to me confirmed in the highest degree by the researches undertaken for the elucidation of the problem of which we are treating. The experiences of M. Bernard in particular, relative to the action exercised by anæsthetics upon plants as well as upon animals, makes it impossible for us to doubt for a momentthe intervention of an agent distinct from physico-chemical forces in organic beings. In employing the wordLifeto designate this agent, I only make use of an established expression, without pretending to go beyond the information gained from experiment and scientific observation.
Beings, in which life alone is added to gravitation and etherodynamy constitute theVegetable Kingdom. Now there is one general fact displayed by this group, the significance of which has not, it seems to me, been sufficiently understood. With the exception of certain phenomena ofunconscious irritabilitywhich have long been known in some plants of a superior order, and of facts, probably of the same class, which have been established chiefly with reference to some reproductive organs of plants of an inferior order, every movement which takes place in plants appears to be producedsolelyby inanimate forces. The transfer of matter in particular, which is necessary for the development and sustenance of every vegetable, belongs to actions of this kind. Can we believe that these forces, as they are known to us from innumerable experiments, could, if left to themselves, have formed an oak, or even raised a mushroom? Can we believe that they could haveorganisedthe acorn or the spore, and hidden in those minute bodies the power of reproducing the parent? And yet without them the vegetable cannot exist. But, in my opinion, nothing makes their real subordination more apparent than the importance of their part in the process of execution. They may be compared to workmen raising an edifice under the eye of the architect who has made the plan.
Are we then to conclude that life is an intelligent force, conscious of the part it plays, and enjoying the dominion it exercises over the subordinate inanimate forces? Not at all. Like these forces, it is ruled by general and fixed laws. Nevertheless, we do not find in the application of these laws, and in the results to which they lead, the mathematical precision of the laws and phenomena of gravitation and etherodynamy. Their mode of action merely seems to oscillatebetween limits which remain impassable. This kind of liberty, and the bounds imposed upon it, are conspicuous in the constant diversity of the products of life, a diversity which contrasts in so striking a manner with the uniformity of the products of etherodynamy. Crystals, when similar in composition, and when formed under similar circumstances, resemble each other perfectly; but we never find two leaves exactly alike upon the same tree.
The vegetable kingdom is, therefore, characterised bythree kinds of phenomena:the Keplerian movement,physico-chemical phenomena, andvital phenomena, which may be ascribed to the action of three forces:Gravitation,Etherodynamy, andLife.
VI. We find repeated among animals all the phenomena which we have noticed amongst plants, and, especially in the highest orders, those movements due to unconscious irritability, of which examples are presented by plants. Some eminent men, Lamarck among the number, have even wished to refer all acts performed by inferior animals to this order of phenomena. But here the author ofLa Philosophie Zoologiquehas fallen into an anatomical error, which has been long since recognised; and whoever has lived, even for a short time, by the sea-side, or has followed closely the habits and actions of worms and zoophytes will certainly protest against this manner of regarding them.
Passing from the plant to the animal, the latter executes movements belonging either to the part or to the whole which are perfectly independent of the laws of gravitation and etherodynamy. The regulating and determining cause of these movements is evidently within the animal itself. It is theWill. But the Will itself is intimately connected withsensibilityandconsciousness. To everyone who judges animals by what he finds takes place within himself, personal experiment and observation prove that the animalfeels,judges, andwills, that is to sayreasons, and consequently isintelligent.
This proposition will, I know, be contested by men whoselearning I profoundly respect, and objections will be made on all sides. On the one hand the Automatism of Descartes will be revived in some schools, and will now be supported by physiology and the experiments of vivisection. I am far from denying the great interest which is attached to the latter, and to the phenomena of reflex actions. But the conclusions which are drawn from them appear to me singularly exaggerated; Carpenter has rightly opposed them with personal experiment. I will add that the study of animals placed far below, and certainly inferior to, the frog, would doubtless lead to very different interpretations. Moreover, Huxley himself admits that animals are probablysensibleandconscious automata. But if they were merely machines we should be obliged to allow that they performed their functionsas ifthey felt, judged, and willed.
On the other hand, in the name of philosophy and psychology, I shall be accused of confounding certainintellectualattributes of the humanreasonwith the exclusivelysensitivefaculties of animals. I shall presently endeavour to answer this criticism from the standpoint which should never be quitted by the naturalist, that, namely, of experiment and observation. I shall here confine myself to saying that, in my opinion, the animal isintelligent, and, although arudimentarybeing, itsintelligenceis nevertheless of thesame natureas that of man. It is, moreover, very unequally distributed among the animal species; in this respect there are many intervening stages between the oyster and the dog.
In addition to the phenomena which spring from the intelligence and reasoning, we find in animals other impulses which arise fromInstinct, a blind impulse, or at least apparently so, which often is the characteristic of animal species, and with which each individual is endowed. These two orders of facts are very often confounded, but the confusion can be explained as follows. In the first place, instinct has as its object the attainment of a determined and fixed result, but in the multitude of ways and means necessary to attain this resulta portion which is often very large is due to the intelligence. The distinction is not always easy. It will, moreover, be apparent that I cannot here enter into the details required by the examination of this question, so entirely foreign to that which is before us.
Besides the acts of intelligence and instinct, phenomena have been established among animals which are closely connected with what we callcharacter,sentiment, orpassion. The familiarity of the terms is in itself a proof that upon this point ordinary observation has outstripped scientific examination.
All these phenomena are perfectly new and have no analogy with those which we have noticed in the preceding kingdoms. They evidently justify the formation of an equally important group. Theanimal kingdomis thus universally admitted, independently of every theory which attempts to explain its characters.
Facts radically different cannot be attributed to the same cause. We must admit, then, that the characteristic phenomena of the animal depend upon something different to those met with in the vegetable or mineral kingdoms. They are, moreover, united by such intimate relations, that it would be impossible not to attribute them to a single cause. From motives already mentioned we will give a name to thisUnknown Cause, and, making use of an expression already established, though open, I can see, to more than one criticism, we will call it theAnimal Mind(l’âme animale).
Does the animal mind liberate the beings it animates from the inferior forces? By no means, for we find them repeated with all their characteristics. In order to raise the least of its organs, the animal must contend with weight; it cannot perform the smallest movement without the intervention of physico-chemical phenomena; it cannot breathe, and, therefore, cannot live, without constantly consuming some of its constituents. In the animal, moreover, just as much as in the plant, the inanimate forces, etherodynamy especially,appear in their double character of constancy and of ubiquity in the accomplishment of phenomena, and of subordination to life, which governs their action in the animal as in the plant.
Moreover, a large part is reserved for purely vegetative life in animals of the highest order. The entire organism is formed without any intervention of the animal mind. Again, a certain number of organs always escape more or less from the influence of the latter, and seem to be subject to life alone. Now these organs are precisely those upon whichnutrition, and consequently the constitution and duration of the whole, depend. Thus life, which reigned supreme in the vegetable kingdom, now in its turn, appears in a subordinate character. We might say that it was essentially entrusted with the organisation and maintenance of the instruments of the animal mind.
As to the latter, even where its intervention is most questioned, it is only revealed to observation byvoluntary movements. Now personal experiment and the faculty of reasoning, are necessary to enable us to comprehend the nature, and appreciate the signification of these movements. It is only by regarding himself as normal, that man can judge of the animal, a subject to which I shall presently return.
Phenomena of four kindsare then characteristic of the Animal Kingdom:phenomena of the Keplerian movement;physico-chemical phenomena;vital phenomena; andphenomena of voluntary movement; attributable to the action of four forces:gravitation,etherodynamy,life, and theanimal mind.
VII.Although the precedingstatements are so much abridged, I have thought it well to give the condensed results in the following table: