There are in nature two classes of beings, two classes of properties, and two classes of sciences. The beings are either organic or inorganic, the properties vital or non-vital, and the sciences physiological or physical. Animals and vegetables are organic—minerals are inorganic. Sensibility and contractility are vital properties; gravity, elasticity, affinity, &c. are non-vital properties. Animal and vegetable physiology, and medicine form the physiological sciences; astronomy, physics, chemistry, &c. are the physical sciences. These two classes of sciences have relation only to different phenomena; there are two other classes that correspond to these, which relate to the internal and external forms of bodies and their description. Botany, anatomy, and zoology, are the sciences of organic bodies; mineralogy, &c. of the inorganic. The first will occupy us, and we shall fix our attention especially upon the relations of living bodies with one another, and their relations with those that do not live.

I. General remarks upon physiological and physical sciences.

The differences between these sciences are derived essentially from those existing between the properties that preside over the phenomena, which are the object of each class of sciences. So immense is the influence of these properties, that they are the principle of all phenomena; whether we examine those of astronomy, of hydraulics, of dynamics, of optics, of acoustics, &c. we shall finally arrive by a connexion of causes to gravity, to elasticity, &c. as the end of our researches. So the vital property is the primum mobile to which we must ascend, whether we consider the phenomena of respiration, of digestion, of secretion, circulation, inflammation, fevers, &c.—In giving existence to every body, nature has imprinted upon it a certain number of properties, that particularly characterize it, and by means of which it contributes in its own manner, to all the phenomena that are developed, succeed, and continually connect themselves in the universe. Cast your eyes upon that which surrounds you; turn them upon objects the most distant; whether, aided by the telescope, they examine those that swim in space, or, armed with the microscope, they enter the world of those, whose minuteness almost evades our view, every where you will find on one side physical properties, on the other vital properties, brought into action; every where you will see inert bodies gravitating upon each other, and reciprocally attracting; living bodies gravitate also, but above all they feel, and possess a motion which they owe only to themselves.

These properties are so inherent in bodies, that we cannot conceive of their existence without them. They constitute their essence and their attribute. To exist and to enjoy them are two things inseparable. Suppose that of a sudden they are deprived of them; instantly all the phenomena of nature cease, and matter alone exists. Chaos was only matter without properties; to create the universe, God endowed it with gravity, elasticity, affinity, &c. and to a part he gave sensibility and contractility.

This mode of considering the vital and physical properties, sufficiently shews, that we cannot ascend above them in our explanations, that they afford the principles, and that these explanations are to be deduced from them as consequences. The physical sciences, as well as the physiological, then, are composed of two things; 1st. the study of phenomena, which are effects; 2d. the research into the connexions that exist between them and the physical or vital properties, which are the causes.

For a long time these sciences have not been so considered; every fact that was observed, was made the subject of a particular hypothesis. Newton was the first to remark, that however variable the physical phenomena were, they could all be referred to a certain number of principles. He analyzed these principles and found that attraction enjoyed the most important place among them. Attracted by each other and by their sun, the planets describe their eternal courses; attracted to the centre of our system, the waters, air, stones, &c. move or tend to move towards it: it is truly a sublime idea, and one that serves as the basis to all the physical sciences. Let us render homage to Newton; he was the first who discovered the secret of the Creator, viz. A simplicity of causes reconciled with a multiplicity of effects.

The epoch of this great man was the most remarkable of human wisdom. Since that period, we have had principles from which we draw facts as consequences. This epoch, so advantageous to the physical sciences, was nothing to the physiological; what do I say? it retarded their progress. Mankind soon saw nothing but attraction and impulse in the vital phenomena.

Boerhaave, though brilliant in genius, suffered himself to be dazzled by a system which misled all the men of learning of his age, and which made a revolution in the physiological sciences, that may be compared to that effected in the physical, by the vortices of Descartes. The plausibility of the theory and the celebrated name of its author, gave to this revolution an empire, which, though rotten in its foundation, was not easily overthrown.

Stahl, less brilliant than profound, rich in the means that convince, though deficient in those that please, formed for the physiological sciences an epoch more worthy of notice than that of Boerhaave. He perceived the discordance between the physical laws and the functions of animals; this was the first step towards the discovery of the vital laws, but he did not discover them. The soul was to him every thing in the phenomena of life; it was much to neglect attraction and impulse. Stahl perceived that these were not true, but the truth escaped him. Many authors, following his steps, have referred to a single principle, differently denominated by each, all the vital phenomena. This, called the vital principle by Barthez, archeus by Van Helmont, &c. is a speculation that has no more reality than that which would refer to a single principle all the physical phenomena. Among these we know that some are derived from gravity, some from elasticity, others from affinity, &c. The same in the living economy, some are derived from sensibility, others from contractility.

Unknown to the ancients, the laws of life have begun to be understood during the last age only. Stahl had already remarked the tonic motions, but he did not generalize their influence. Haller was engaged particularly with sensibility and irritability; but in limiting one to the nervous system, and the other to the muscular, this great man did not consider them in the correct point of view; he made them almost insulated properties. Vicq d'Azyr changed them into functions in his physiological division and ranked them with ossification, digestion, &c. that is, he confounded the principle with the consequence. Thus you see, notwithstanding the labours of a crowd of learned men, how much the physiological sciences still differ from the physical. In these, the chemist refers all the phenomena that he observes to affinity: the natural philosopher, in his science, every where sees gravity, elasticity, &c. In the others, we have not as yet ascended, at least in a general manner, from the phenomena to the properties from which they are derived. Digestion, circulation, or the sensations, do not bring the idea of sensibility or contractility to the mind of the physiologist, as the movement of a watch proves to the mechanician that elasticity is the primum mobile of its motion; or as the wheel of a mill or of any machine, which running water sets in motion, proves to the natural philosopher that gravity is the cause. To place upon the same level in this respect these two classes of sciences, it is evidently necessary to form a just idea of vital properties. If their limits are not accurately assigned, we cannot with precision analyze their influence. I shall present here only general considerations on this point, which has been treated sufficiently in my Researches upon Life; what I shall add now will be but as a supplement to what has been explained in that work.

II. Of vital properties, and their influence upon all the phenomena of the physiological sciences.

To assign the limits of these properties, we must follow them from bodies that are hardly developed, to those which are the most perfect. In the plants that seem to form the transition from vegetables to animals, you discover only an internal motion that is scarcely real; their growth is as much by the affinity of particles and consequently by juxta-position, as by a true nutrition. But in ascending to vegetables better organized, you see them continually pervaded by fluids, that circulate in numerous capillary canals, which mount, descend, and run in a thousand different directions, according to the state of the forces that regulate them. This continual motion of fluids is foreign to the physical properties, the vital ones only direct it. Nature has endowed every portion of a vegetable with a faculty of feeling the impression of fluids, with which their fibres are in contact, and of reacting upon them in an insensible manner, to favour their course. The first of these faculties I call organic sensibility, the other, insensible organic contractility. This is very obscure in most vegetables; it is the same in the bones of animals. These two properties govern not only the vegetable circulations, which correspond in some measure to the capillary system of animals, but also the secretion, absorption, and exhalation of vegetables. Remark, in fine, that these bodies have only functions relative to their properties; that all the phenomena that animals derive from properties which they have more than vegetables, as the great circulation and digestion, for which there must be sensible organic contractility; as the sensations, for which there must be animal sensibility; and locomotion, the voice, &c. for which animal contractility is necessary; remark, I say, that these functions are essentially foreign to vegetables, since they have not vital properties to place them in action.

For the same reason the catalogue of their diseases is less extensive. They have not the class of nervous diseases, in which the animal sensibility takes so great a part; they have not those of convulsions or paralysis, which are formed by an augmented or diminished animal contractility; they have not those of fevers, or gastric diseases, which evidently arise from a disorder in the sensible organic contractility. The diseases of vegetables are tumours of various kinds, increased exhalations, marasmus, &c.; they all indicate a derangement in the organic sensibility and in the corresponding insensible contractility.

If we pass from vegetables to animals, we see the lowest of these, the zoophites, receive into a sac, which is alternately filled and emptied, the aliments that are to nourish them; we see them begin to unite sensible organic contractility or irritability to the properties which they have in common with vegetables, and consequently commence the performance of different functions, digestion in particular.

Thus far the organized bodies live wholly within themselves; they have no relation with that which surrounds them; animal life is wanting in them, or at least if it has commenced in these animo-vegetables, its rudiments are so obscure that we can hardly discover them. But this life begins to display itself in the superior classes, in worms, insects, mollusca, &c. On the one hand, the sensations, and on the other, locomotion, which is inseparable from them, are more or less fully developed. Then the vital properties necessary to the exercise of these new functions, are added to the preceding. Animal sensibility and contractility, obscure in the lower species, become more perfect, as we approach quadrupeds, and locomotion and the sensations become also more extensive. Sensible organic contractility then increases, and in proportion to that, digestion, circulation of the great vessels, &c. which are governed by it, receive a development which is constantly growing more perfect.

If we strictly examine the immense series of living bodies, we shall see the vital properties gradually augmenting in number and energy, from the lowest of plants to the first of animals, man; we shall see the lowest plants obedient to vital and physical properties; all plants are governed only by these, which, in them, consist of insensible contractility and organic sensibility; the lowest animals begin to add sensible organic contractility to these properties, afterwards animal sensibility and contractility. We know the expression of LinnÆus, which he has used to characterize minerals, vegetables, and animals. The following would be more correct: 1st. physical properties for minerals; 2d. physical properties and organic vital properties, except2 sensible contractility, for vegetables; 3d. physical properties, all the organic vital properties, and the animal vital properties, for animals.

Man and the neighbouring species, which are the particular object of our researches, enjoy then evidently, all the vital properties, some of which belong to organic life, the others to animal life. 1st. Organic sensibility and insensible contractility have all the phenomena of the capillary circulation, of secretion, of absorption, exhalation, nutrition, &c. evidently dependant upon them in a state of health. In treating, therefore, of these functions, we must always ascend to these properties. In the state of disease, all the phenomena that suppose a disorder in these functions, are clearly derived from an injury of these properties. Inflammation, formation of pus, induration, resolution, hemorrhage, unnatural augmentation or suppression of secretions; increased exhalation, as in dropsies; diminished, or wholly wanting, as in adhesions; absorption, disordered in some way or other; nutrition, altered more or less, or presenting unnatural phenomena, as in the formation of tumours, cysts, cicatrices, &c.: these are morbid symptoms, that evidently suppose some injury or disorder in these two preceding properties. 2d. Sensible organic contractility, which, like the preceding, is not separated from the sensibility of the same nature, governs especially in a state of health, the movements necessary to digestion and the circulation of the great vessels, at least for the red and black blood of the general system, for the excretion of urine, &c. In the state of disease, all the phenomena of vomiting, of diarrhoeas, and a great part of those numberless ones of the pulse, may ultimately be referred to a disorder of the sensible organic contractility. 3d. All the external sensations, those of seeing, hearing, smelling, tasting, and feeling, and the internal, as those of hunger, thirst, &c. are derived in a state of health from the animal sensibility. In disease, what part does not this property perform? Pain and its innumerable modifications, itching, smarting, tickling, the sensation of heaviness, weight, lassitude, throbbing, pricking, pulling, &c. &c. are not these only different alterations of animal sensibility? A hundred different words would not express the diversity of painful sensations that morbid affections bring with them. 4th. Animal contractility is the principle of locomotion and the voice; convulsions, spasms, palsies, &c. are derived from an augmentation or diminution of this property. Examine all the physiological and all the pathological phenomena, and you will see that there is no one which cannot be ultimately referred to some one of the properties of which I have just spoken. The undeniable truth of this assertion, brings us to a conclusion not less certain in the treatment of diseases, viz. that every curative method should have for its object the restoration of the altered vital properties to their natural type. Every remedy, which, in local inflammation, does not diminish the augmented organic sensibility; which, in oedema and dropsy, does not increase this weakened property; and which does not reduce animal contractility in convulsions, and elevate it in paralysis, fails in its object, and is contraindicated.

To what errors have not mankind been led in the employment and denomination of medicines? They created deobstruents, when the theory of obstruction was in fashion, and incisives, when that of the thickening of the humours prevailed. The expressions of diluents and attenuants, and the ideas that are attached to them, were common before this period. When it was necessary to blunt the acrid particles, they created inviscants, incrassants, &c. Those who saw in diseases only a relaxation or tension of the fibres, the laxum and strictum as they called it, employed astringents and relaxants. Refrigerant and heating remedies were brought into use by those who had a special regard in diseases to an excess or a deficiency of caloric. The same identical remedies have been employed under different names according to the manner in which they were supposed to act. Deobstruent in one case, relaxant in another, refrigerant in another, the same medicine has been employed with all these different and opposite views; so true is it that the mind of man gropes in the dark, when it is guided only by the wildness of opinion.

There has not been in the materia medica, a general system; this science has been governed by the different theories that have successively predominated in medicine; each has, if I may so express myself, flowed back upon it. Hence the vagueness and uncertainty that it presents at this day. An incoherent assemblage of incoherent opinions, it is perhaps of all the physiological sciences, that which best shows the caprice of the human mind. What do I say? It is not a science for a methodical mind, it is a shapeless assemblage of inaccurate ideas, of observations often puerile, of deceptive remedies, and of formulÆ as fantastically conceived as they are tediously arranged. It has been said that the practice of medicine was disgusting; I add further, that it is not in some respects the study of a reasonable man, when its principles are derived from the greatest part of the works on the materia medica. Take away those medicines, the effect of which is known only by accurate observation, as evacuants, diuretics, sialagogues, anti-spasmodics, &c. those consequently that act upon a particular function; what knowledge have we of the remainder?

It is, without doubt, extremely difficult at present to class remedies according to their modus operandi; but it is undeniable that all have for their object, the restoration of the vital forces to the natural type, from which they have been driven by disease. Since the morbid phenomena may be considered as different alterations of these forces, the action of remedies should also be viewed as the means by which these alterations are to be brought back to the natural type. Upon this principle, each of the properties has its class of appropriate remedies.

1st. We have seen that there is in inflammations an increase of organic sensibility and insensible contractility; diminish then this increase by cataplasms, fomentations, and local baths. In some dropsies, in white-swellings, &c. there is a diminution of these properties; raise them by the application of wine and all those substances that are called tonics. In every species of inflammation, suppuration, tumours of different kinds, ulcers, obstructions; in every alteration of secretion, exhalation, or nutrition, the remedies act peculiarly upon the insensible contractility, to increase, diminish, or alter it in some way. All those that are called resolvents, tonics, stimulants, emollients, &c. act upon this property. Observe, that these remedies are of two kinds: 1st. general; as wine, ferruginous substances, oftentimes the acids, &c.; these re-animate insensible contractility, and give tone to the whole system: 2d. particular; thus this property is separately excited by nitre in the kidnies, mercury in the salivary glands, &c.

2d. Many remedies act particularly upon the sensible organic contractility; such are emetics, which produce a contraction of the stomach; cathartics, and drastics especially, which create a strong contraction of the intestines. Art does not excite the heart in the same manner as these viscera; we do not artificially increase its movements as we do those of the stomach in gastric diseases. It will, perhaps, hereafter be attempted, especially if it is true that fever may often be a method of cure, and then it will not, I think, be difficult to find the means of effecting it. At other times, we have to diminish sensible organic contractility, and then remedies are employed that act in a manner opposite to the preceding, as in stopping vomitings, in diminishing intestinal irritation, &c.

3d. Animal sensibility has also remedies that are peculiar to it. But they act in two ways—1st. in diminishing pain in the part where it is seated, as different applications upon tumours, obstructions, &c.: 2d. in acting upon the brain that perceives the pain; thus all narcotic preparations, taken internally, remove the sensation of pain, while the cause still subsists. In cancer of an ulcerated uterus, the disease continues its progress with activity, but the prudent physician stupifies the brain so much, that it is incapable of perceiving it. It is essential to distinguish accurately these two actions of remedies upon the animal sensibility. They are totally different from each other.

4th. Medicinal substances have also their influence on animal contractility. Every thing that produces an active excitement on the external surface of the body, as vesicatories, frictions, smarting, &c. tends to re-animate in paralysis this benumbed faculty. All those substances that paralyze the cerebral action, prevent the brain from governing the muscles of animal life; when these muscles, therefore, are convulsively agitated, these substances are true anti-spasmodics.

In presenting these observations, I do not mean to offer a new plan for the materia medica. Medicines are too complicated in their action to be arranged anew, without more reflection than I profess as yet to have bestowed on the subject. Moreover, an inconvenience common to every classification, would here present itself: the same medicine acts often upon many vital properties. An emetic, while it brings into action the sensible organic contractility of the stomach, excites the insensible contractility of the mucous glands, and oftentimes the animal sensibility of the nervous villi. The same observation may be made with regard to the stimulants of the bladder, of the intestines, &c. My only object is to show, that in the action of substances applied to the body to heal it, as in the phenomena of diseases, every thing must be referred to the vital properties, and that their augmentation, diminution, or alteration, are ultimately the invariable object of our curative method.

Some authors have considered diseases only as increased strength or weakness, and have consequently divided medicines into tonics and debilitants. This idea is true in part, but it is false when we generalize it too much. For every vital force there are means proper to raise it when too much diminished, and to lessen it when too much elevated. But tonics and debilitants are certainly not applicable to every case. You would not weaken animal contractility, augmented in convulsions, as you would insensible organic contractility increased in inflammation; neither would you increase them by the same means. The morbid phenomena that organic contractility and animal sensibility experience, are not cured by the same method. There are medicines proper for each vital force. Moreover, it is not only in increase or diminution that the vital forces err, but they are besides disordered; the different modifications that insensible contractility and organic sensibility can undergo, produce in wounds and ulcers a diversity of suppuration, in glands a diversity of secretion, in exhaling surfaces a diversity of exhalations, &c. It is necessary, therefore, that medicines should not only diminish or increase each of the vital forces, but that they should moreover restore them to the natural modification from which they have been altered.

What I have just said is particularly applicable to the strictum and laxum of many authors, who every where see but these two things. The strictum may be properly applied to inflammation, the laxum to dropsies, &c.; but what have these two states of the organs in common with convulsions, with disorder of the intellect, with epilepsy, with bilious affections, &c.? It is the peculiarity of those who have a general theory in medicine, to endeavour to bend every phenomenon to it. The fault of generalizing too much, has been perhaps more injurious to science, than that of viewing each phenomenon separately.

These observations are, I think, sufficient to show, that every where in the physiological sciences, in the physiology of vegetables and of animals, in pathology, in therapeutics, &c. there are vital laws, that govern the phenomena which are the object of these sciences; and that there is not one of these phenomena that does not flow from these essential and fundamental laws, as from its source.

If I should take a survey of all the divisions of physical sciences, you would see that the physical laws were ultimately the sole principle of all their phenomena; but this is so well known that it is not necessary to do it. I will consider an important subject, and one to which we are naturally led by the preceding observations. I mean, a parallel between physical and vital phenomena, and consequently between physical and physiological sciences.

III. Characteristics of the vital properties, compared with those of the physical.

When we consider, on one side, the phenomena which are the object of the physical sciences, and those that are the object of the physiological, we see how immense is the space that separates their nature and their essence. But this difference arises from that which exists between the laws of the one and the other.

Physical laws are constant and invariable; they are subject neither to augmentation or diminution. A stone does not gravitate towards the earth with more force at one time than another; in every case marble has the same elasticity, &c. On the other hand, at every instant, sensibility and contractility are increased, diminished, or altered; they are scarcely ever the same.

It follows, therefore, that the physical phenomena are never variable, that at all periods and under every influence they are the same; they can, consequently, be foreseen, predicted, and calculated. We calculate the fall of a heavy body, the motion of the planets, the course of a river, the ascension of a projectile, &c.: the rule being once found, it is only necessary to make the application to each particular case. Thus heavy bodies fall always in a series of odd numbers; attraction is in the inverse ratio of the square of the distances, &c. On the other hand all the vital functions are susceptible of numerous variations. They are frequently out of their natural state; they defy every kind of calculation, for it would be necessary to have as many rules as there are different cases. It is impossible to foresee, predict, or calculate, any thing with regard to their phenomena; we have only approximations towards them, and even these are often very uncertain.

There are two things in the phenomena of life, 1st. the state of health; 2d. that of disease; hence there are two distinct sciences; physiology considers the phenomena of the first state, pathology those of the second. The history of the phenomena in which the vital forces have their natural type, leads us to consider as a consequence, those phenomena that take place when these forces are altered. But in the physical sciences there is only the first history; the second is never found. Physiology is to the movements of living bodies, what astronomy, dynamics, hydraulics, hydrostatics, &c. are to those of inert ones; but these last have no such correspondent sciences as pathology. There is nothing in the physical sciences that corresponds to therapeutics in the physiological. For the same reason, every idea of medicament is absurd in the physical sciences. The object of a medicament is the restoration of properties to their natural type; but, the physical properties, never losing this type, have of course no need of restoration.

We see then that the peculiar instability of the character of the vital laws is the source of an immense series of phenomena, which form a peculiar order of sciences. What would become of the universe, if the physical laws were subject to the same commotions and the same variations as the vital? Much has been said of the revolutions of the globe, of the changes that the earth has undergone, of the overthrows that ages have gradually brought about, and upon which ages have accumulated without producing others: but you would see these overthrows and these general commotions in nature at every instant, if the physical properties had the same character as the vital.

For the same reason, that the phenomena and laws of the physical and physiological sciences are unlike, the sciences themselves are essentially different. The manner of presenting the facts and of prying into their causes, the experimental art, &c. every thing bears a different stamp; and it is absurd to confound them. As the physical sciences were perfected before the physiological, mankind thought that they could illustrate the latter by connecting them with the former; but they have confused them; and this was inevitable, for the application of the physical sciences to physiology, was the explication of the phenomena of living bodies by the laws of the inert. Here then is a false principle, and all the consequences drawn from it must be erroneous. Let us leave to chemistry its affinity, and to physics its elasticity and gravity, and let us employ in physiology only sensibility and contractility; I except, however, those cases where the same organ becomes the seat of vital and physical phenomena, as the eye and the ear, for example. It is on this account, that the general character of this work is wholly different from those on physiology, and even that of the celebrated Haller. The works of Stahl illustrate well the advantage of neglecting all those pretended accessory aids, which overthrow the science in attempting to support it. But as this great physician had not analyzed the vital properties, he could not present their phenomena in their true point of view. Nothing is more vague and indefinite than the words, vitality, vital action, vital influx, &c. when we do not precisely limit their meaning. Suppose that mankind had created some general and vague words, which were to correspond to all the non-vital properties, and which gave no precise or definite ideas; if you were every where to use these terms, if you did not determine that which belonged to gravity, that which depended on affinity, and that which was the result of elasticity, you would never be understood. Let us say as much in regard to the physiological sciences. The art is much indebted to many physicians of Montpellier for having deserted the theory of Boerhaave, and having followed in preference that given by Stahl. But in leaving a bad path, they have taken another so tortuous, that they will never, I think, find its termination.

Ordinary minds, in reading, stop at insulated facts that are presented; they do not embrace, at one view, the principles of the work. Oftentimes the author himself incautiously follows the impression given to a science in the age in which he writes. But the man of genius every where pauses at this impression, which should be henceforth entirely different in physical and physiological works. It is necessary to use a different language; for most of the words that are carried from the physical into the physiological sciences, continually refer to ideas that have no connexion with them. You see the living solids constantly undergoing composition and decomposition, every moment taking and rejecting new substances; on the other hand, inert bodies remain the same, and keep the same constituent principles, until friction and other causes destroy them. So in the elements of inert bodies, there is a constant uniformity, and an invariable identity in their principles, which is known when they have been once analyzed; whilst the principles of the living fluids are so continually changing, that it is necessary that many analyses should be made, under every possible circumstance. We shall see the glands and exhaling surfaces pour out, according to the degree of their vital forces, a great variety of modifications of the same fluid; what do I say? they pour out a variety of fluids really different; for are not the sweat and the urine poured out under one circumstance, and the sweat and the urine under another, two distinct fluids? There are a thousand examples that would incontestably establish this assertion.

It is the nature of vital properties to exhaust themselves; time wastes them. Elevated in the commencement of life, they remain stationary at the adult age, and afterwards are debilitated and become nothing. Prometheus, it is said, having formed some statues of men, snatched fire from heaven to animate them. This fire is the emblem of the vital properties; while it burns, life is supported; when it is extinguished, it ceases. It is, then, a part of the essence of these properties, to animate matter for a determinate time only; hence there are necessary limits to life. On the other hand, the physical properties, constantly inherent in matter, never abandon it; so that inert bodies have no limits to their existence, but what accident gives to them.

By nutrition the particles of the matter of inanimate bodies pass into living bodies, and vice versa; and we can evidently conceive that this matter has been endowed through an immense series of ages with physical properties. These properties are given to it at the creation, and will leave it only when the world shall end. This matter, in passing into living bodies, in the space that separates these two epochs, a space that immensity only can bound, this matter, I say, becomes possessed, at intervals, of vital properties, which are then united to physical properties. Here, then, is a great difference in matter, with regard to these two kinds of properties; one it enjoys by intermissions only, the other it possesses constantly.

I could add many other considerations, that would still further establish the difference between the physical and vital laws, and consequently between the physical and vital phenomena, and as a consequence from these, the difference of the general character and methods of the physical and physiological sciences. I could show, that inert bodies are formed at hazard, by juxta-position or a combination of their particles, while living bodies, on the contrary, exist in consequence of a certain function, viz. generation; that the first increase in the same manner as they are formed, by juxta-position or the combination of new particles; the others by an internal movement of assimilation, which requires different preliminary functions; these constantly experiencing composition and decomposition; those remaining always internally in the same condition, undergo no other modifications than such as are derived from chance and the physical laws. The existence of inert bodies ceases as it commenced, by mechanical laws, by friction, or by new combinations; living bodies afford in their natural destruction, a phenomenon as uniform as in their production; they pass suddenly to a new state when life abandons them, and undergo putrefaction, desiccation, &c. which they did not before, because the physical properties being restrained by the vital, could not produce these phenomena; inert bodies, on the other hand, always preserve the same modifications. Though a stone or a metal, when broken or dissolved, ceases to exist, their particles will always be the same. But some authors have already presented a great part of this parallel; let us content ourselves with drawing from it a consequence often deduced from other facts, I mean the difference of the laws that preside over the two classes of functions.

But there is an essential difference between vital and physical properties; I refer to sympathies.

All inert bodies show no communication in their different parts. Though the extremity of a stone, or of a metal, may be altered in any way by chemical dissolution, or by mechanical agents, the other parts are not affected; it is necessary to touch them by a direct action. On the contrary, every thing is so connected and tied together in the living body, that no one part can be disordered in its functions, without being immediately perceived by the rest. All physicians have known the singular consent that exists between our different organs, both in a state of health and disease, but principally in the latter. How easy would be the study of diseases, if they were stripped of every thing derived from sympathy! Who does not know that these complaints often predominate over those that arise from the injury of the diseased organ? Who does not know that the cause of sleep, of exhalation, of absorption, of secretion, of vomiting, of diarrhoea, of retention of urine, of convulsions, &c. is oftentimes very far from the brain, from the exhalants, from the absorbents, from the glands, from the stomach, from the intestines, from the bladder, from the voluntary muscles, &c.?

How little soever we reflect on the sympathetic phenomena, it will be evident that they are only unnatural developments of vital forces which are called into action in an organ by the influence that it receives from those that have been directly excited. In this view all the systems are dependant upon each other. This important point of doctrine will be treated at so much length, in this work, particularly under the article on the nervous system that it is useless to insist much upon it here.

We shall see sympathies call into action always those vital properties especially that prevail in a system; animal sensibility in the nerves, contractility of the same kind in the voluntary muscles, insensible organic contractility in the involuntary, sensible contractility in the glands, in the serous, mucous, synovial, cutaneous surfaces, &c. We shall see them assume the character of the vital properties of the organs in which they are developed, their progress will be chronic in the bones, cartilages, &c. acute in the muscles, skin, &c. We shall see them observe in the frequency of their development, the laws of nutrition and growth, to appear oftener in the nervous and vascular system of the child, in the pulmonary organs in youth, and in the abdominal contents in adult age. But let us pass to other subjects.

IV. Of the vital properties and their phenomena, considered in relation to the solids and fluids.

Every organized body is composed of fluids and of solids. The first are, in one point of view, the materials, and in another the residue of the second. 1st. They are the materials, for from the aliments which convey through the intestines, the elements of nutrition, even to the interior of the organs where these elements are deposited, they form evidently a part of the chyle and the blood. 2d. They are the residue, for after having remained some time in the organs, these nutritive particles are taken up, enter again into the blood, and afterwards make a part of the secreted fluids, and of those that form cutaneous and mucous exhalations, which are thrown out externally.

There are then fluids for composition and others subservient to decomposition. The solids are the termination of the first, which come from without, and the place from which the second are sent back. The fluids of composition and decomposition are not all insulated; the chyle, the materials that enter by cutaneous absorption, the principles that the lungs draw from the air, &c. are especially of the first kind. The fluids secreted and exhaled upon the mucous and cutaneous surfaces, appear to be exclusively of the second. But the blood is a common centre, in which the elements that enter, and those that go out, circulate together.

This being admitted, let us see what part the fluids and the solids enjoy in the vital phenomena. This must evidently depend on the properties they possess; and in reflecting on the vital properties which we know, it is evident, that every idea of fluidity is foreign to them, that fluidity cannot be the seat of any contraction nor of organic and animal sensibility, &c. I will not speak here of the pretended spontaneous movements of the blood, of the subtle fluids that it contains, according to some authors, and which can on occasion expand or contract it; all this is but an assemblage of vague ideas, that are confirmed by no experiment. Moreover, all the phenomena of the living economy show us manifestly the fluids in a state almost passive, and the solids, on the other hand, always essentially active. It is the solids that every where receive the excitement, and act in consequence; the fluids are only the excitants. This constant impression of the second upon the first, constitutes every where continual sensations that are not referred to the brain, and which are consequently not perceived; this is organic sensibility, and differs from the animal in this, that the mind has no consciousness of these sensations, which do not go beyond the organs in which they take place.

Since, on one side, the vital properties are essentially seated in the solids, and on the other, the morbid phenomena are but alterations of these properties, it is evident that these phenomena reside especially in the solids, and that to a certain limit the fluids are foreign to them. Every kind of pain, all spasms and irregular movements of the heart, that constitute the innumerable variations of the pulse, have their seat in the solids.

Let us not believe, however, that the fluids are nothing in diseases; they oftentimes carry the fatal principle of them. They possess, then, in disease, the same place as in the state of health, in which the solids are the active agents of all the phenomena that we observe, but their action is inseparable from that of the fluids. That the heart may contract, that the capillary system may close itself, it is necessary that fluids should first go there. In proportion as the fluids are in their natural state, the excitement is natural; but when this is changed from any cause, as by the introduction of foreign substances, at that instant they become unnatural excitants; the functions are disordered, and diseases supervene. You see, then, that the fluids can oftentimes be the principle of diseases, and the vehicle of morbific matter. But this subject merits further consideration.

Here we can apply the distinction of fluids into those of composition and those of decomposition. The first, which enter the system in various ways, go into the blood, which, on one account, belongs to them, but on another, to the fluids of decomposition. It is incontestable, 1st. that the chyle can be loaded with a variety of foreign substances, and carry into the blood the fatal principles of disease, as when putrid and badly digested matter, principles of contagion mixed with our aliment, &c. are found in the primÆ viÆ. 2d. Is it not established by many proofs, that cutaneous absorption oftentimes introduces into the blood the causes of disease, and, 3dly. that substances foreign to the constituent principles of the air, and adapted to excite disease, may accidentally get into that fluid through the medium of the lungs? these things we cannot doubt. Here, then, there are already three ways open to the principles of morbific matter, as we shall moreover have reason to be convinced in the course of this work. 4th. There is another accidental one, that arises from wounds, cuts, bites, lacerations, &c. by means of which destructive principles are oftentimes conveyed into the animal economy. Under these four we might produce a variety of cases, in which the fluids are the first causes of diseases, by conveying their essential principles and becoming unnatural excitants to the solids, in which they produce phenomena contrary to the natural order. But it is evident, that it is those fluids especially destined to the composition of the organs that thus carry morbific principles; these are especially their vehicle, and convey the disease. On the other hand, the fluids destined to the decomposition tend to carry the disease out of the system. We have seen that these fluids are every where poured upon the mucous and cutaneous surfaces, either by exhalation or secretion, as the sweat, the urine, &c.: and it is by these fluids that a crisis is produced. Physicians have exaggerated to an infinite degree the influence of these morbific humours, thus driven out; but we cannot doubt that this doctrine has oftentimes a real foundation. If these fluids are sometimes the vehicles of disease, it is when they enter unnaturally into the system, as when the bile passes into the mass of blood, when the absorbed urine enters this fluid, &c.

After all that has just been said, it is evident, that it is necessary to distinguish accurately diseases themselves, or rather the whole of the symptoms that characterize them, according to the principles that produce or support them. Almost all the symptoms are in the solids, but the cause can be in them as well as in the fluids. An example will render this more clear; the heart can contract unnaturally; 1st. because its organic sensibility is increased whilst the blood itself remains the same; 2d. because the blood is either augmented, as in plethora, or altered in its nature, as in putrid fevers, &c. while the organic sensibility of the heart does not vary. The excitement may be double, or the organ may be twice as susceptible as common, the effect is the same; an acceleration of the pulse takes place. The solid always takes the principal part in the disease; it is always that which contracts, but in the first case the cause was in the solid, in the second it was not.

This example gives an idea of what occurs in diseases, in all of which the solids are especially in action; but the cause of this action, sometimes exists in them, and sometimes not. It is no doubt essentially necessary to seek the distinction of these cases. The following reflections are made with this view. 1st. I distinguish, in the present question, diseases into two classes; 1st. into those which especially affect animal life; 2d. into those that particularly disorder organic life. I say particularly, for such is the connexion of these two lives, that the one can hardly be altered without the other; thus fevers that affect organic life, produce cerebral effects that agitate the animal: thus also primitive cerebral affections influence sympathetically the circulation, respiration, &c. But certainly we cannot deny, that there are some affections, whose principal and primitive character is a disorder of the animal life; such are convulsions, spasms, paralysis, mania, epilepsy, catalepsy, &c. But it appears that the cause of these diseases is almost always in the solids, and that the fluids most commonly are not affected. Therefore you see that crises, in every case are foreign to these diseases. Hypochondria, hysteria, melancholia, &c. though they appear to reside more particularly in the solids, can yet be in a degree dependant on the fluids, as different examples will prove.

Diseases, on the other hand, that particularly affect organic life, as fevers, inflammations, &c. may have their principle as well in the fluids as in the solids. Hence the reason, that these diseases are subject to crisis, and are cured by evacuants, alteratives, &c.

2dly. It is necessary in order to resolve the question of the affection of the solids or the fluids in diseases, to distinguish their phenomena into those which are sympathetic, and those that are the product of a direct excitement. Every sympathetic phenomenon has its seat essentially and necessarily inherent in the solids. In fine, the solids alone act upon each other and correspond together by means yet unknown. All sympathetic vomiting, febrile agitation of the heart, exhalation, secretion, and absorption, arise from a change effected, by the influence of a part more or less remote, in the solids of those which are the seats of these phenomena. When cold acts upon the skin covered with sweat, immediately the pleura becomes affected. If cold water is conveyed into the stomach while the body is hot, an effect is oftentimes produced upon a distant organ. This is sympathy, and not the repercussion of the humours. In this work I have cited a great number of examples of sympathy under each system; but in none of them I think is it possible to conceive of an affection of the fluids.

3dly. The division of diseases into organic, or those which alter the texture of the organs, and into those which leave this texture untouched, is still essential here. The first have their seat evidently in the solids.

4thly. The division into acute and chronic, ought not to be neglected in resolving the problem.

5thly. In fine, it would be necessary to make another distinction not less important, viz. that of diseases which are independent of every principle inherent in the economy and of those which proceed from a similar principle, as when the virus of the venereal, the tetters, scrofula or scurvy predominates in the whole system, and alternately attacks the different organs.

How little soever you may examine diseases under different points of view, you will perceive that what is true of one class cannot be so of another. It is evident from this, that it is improper to resolve this question in a general manner, as it has been too often done, and that a theory of diseases founded upon the principle of the affection of the solids or fluids alone, is a pathological absurdity, equal to that in physiology which would place in action the fluids or solids only. I think there are two errors that should be equally feared, that of particularizing and that of generalizing too much. The second leads us to false conclusions as well as the first.

Though the vital properties reside especially in the solids, it is not necessary to consider the fluids as entirely inert. It is undeniable, that those of them which form the composition of the body, increase in vitality as they advance from the aliments of which they are formed, to the solids which they compose. The alimentary mass is less animalized than the chyle, and this is less so than the blood. It would undoubtedly be a subject of very curious research, to determine, how the particles, from being foreign to the vital properties, and enjoying only physical ones, become by degrees possessed of the rudiments of the first. I say the rudiments, for certainly the vital elaboration that the fluids experience in circulating as such in the body, and before they penetrate the solids to become a part of them, is the first degree of their vital properties. In the same manner, if you should inject into this fluid the materials of those that are exhaled or secreted, the exhalant and secretory organs would repulse these materials, if life had not made them undergo a previous elaboration.

It is evidently impossible to say what this vitality of the fluids is; its existence however is not less real, and the chemist who wishes to analyze the fluids, has, like the anatomist who dissects the solids, only the dead body upon which he can operate. You will observe, that when the principle of life has left the fluids, they go immediately into a state of putrefaction, and are decomposed like the solids, deprived of their vital powers. This alone prevents that internal movement, which undoubtedly enters much into the alterations of which the fluids are susceptible. Observe what takes place after a meal; ordinarily a slight increase of the pulse, the effect of the mixture of the nutritive principles with the blood, is the consequence of it. If you have made use of acrid or spicy aliments, to which you are unaccustomed, a general heat, a thousand different sensations of lassitude and heaviness, accompany digestion. Shall I speak of the various kinds of wine, and their effects, even to intoxication? Who has not a hundred times paid dearly for the pleasures of a repast by a general disorder, an universal agitation, a heat in every part during the whole time that the wine circulates with the blood? Who has not observed that one kind of wine produces one effect and another a different? The solids are then without doubt the seat of every thing we experience; but is not the cause of it in the fluids? It is the blood, which carrying with its own particles others that are foreign to it, excites all the organs, and especially the brain, because there is a particular relation between this viscus and spirituous liquors, as there is between cantharides and the bladder, and mercury and the salivary glands. That which I say is so true, that if you infuse wine into the open vein of an animal, you will produce analogous effects. The experiments made upon this subject are so well known that I have not even repeated them.

I will relate a fact here which disproves what has lately been advanced upon the incorruptibility of the blood in diseases. A short time since, in examining a body at the HÔtel Dieu, with Mess. PÉborde, l'Herminier, and Bourdet, we found instead of the black abdominal blood, a real grey sanies, which filled all the divisions of the splenic vein, the trunk of the vena porta, and all the hepatic branches, so that by cutting the liver in slices, we could distinguish by the flow of this sanies, all the ramifications of the vena porta from those of the vena cava, which contained ordinary blood. This body was so remarkable for its size, that I do not recollect to have ever seen one equal to it. Certainly this sanies was not the effect of death, and the blood had circulated, if not thus altered, at least very different from its natural state, and really decomposed.

Consider the immense influence of aliments upon health, structure, and even character. Compare the people who live only on milk and vegetables with those who are in the constant use of spirituous liquors. See how alkohol, carried into the new world, has modified the manners and habits of the savages; consider the slow and gradual influence of regimen in chronic diseases, and you will perceive that in health, as in disease, the alteration of the fluids is frequently before that of the solids, which consequently become changed; for it is an inevitable circle. But the alteration of the fluids appears to depend essentially upon the mode of the mixture of parts not animalized with those that are so.

We should have a very inaccurate idea of the mixture with the blood of the foreign substances brought by the way of the intestines, the skin, or the lungs, for the purposes of sanguification, if we compared it to the mixture of inert substances, or chemical combinations. The blood enjoys, if we may so say, the rudiments of organic sensibility; and as the life which it enjoys places it more or less in relation to the fluids that enter it, it is more or less disposed to combine with them and to endow them with the life with which it is animated. Sometimes it repulses for a long time substances that are foreign to it. I am persuaded that a great number of the phenomena that we experience after taking food, especially acrid substances, and spirituous liquors, arises in part from the general disorder that the blood undergoes when its vitality begins to communicate itself to these foreign substances from the kind of struggle which takes place in the vessels, between the living fluid and that which does not live. Thus we see all the solids rise, as it were, against a stimulant they are unaccustomed to. Who knows but that the vitality of the fluids has an influence upon their motions? I think it is very probable. I doubt whether fluids purely inert could, if they were alone in animated vessels, circulate like living fluids. In the same manner, animated fluids could not move themselves, if they were in vessels deprived of life. Life then is equally necessary to one and the other. But these subjects are too obscure to occupy us longer.

V. Of the properties independent of life.

These are what I call properties of texture. Foreign to inert bodies, inherent in the organs of living bodies, they arise from their texture, from the arrangement of their particles, but not from the life that animates them. Thus death does not destroy them. They remain in the organs when life is gone; that, however, adds much to their energy. Putrefaction and the decomposition of the organs, alone destroy them. The two first of these properties are extensibility and contractility of texture. I have explained these sufficiently in my Treatise on Life. I shall have occasion in this work to explain the influence they have in each system. I shall now speak of a property of which as yet very little has been said; which chemists have proved by their experiments, and which physiologists have confounded often with irritability, but which is as distinct from it as it is from the contractility of texture; I mean the property of being3 hardened like horn, and contracted by the action of different agents. This will be examined particularly in each system; I shall now describe it in a general manner only.

Every organized part, submitted either after death or during life, to the action of fire and of certain concentrated acids, is contracted and wrinkled in different ways, and is affected almost like irritable organs when they are excited. Now this property is to be considered as to the agents which put it in action, as to the organs which are the seat of it, and as to its phenomena.

1st. Fire is the principal agent of this horny hardening. Every living organ, placed upon burning coals, is suddenly raised to the highest degree. 2d. Next to fire, the strongest acids, the sulphuric first, then the nitric, then the muriatic, make the animal fibres contract most suddenly. As they are diluted, they lose this power, and the acids that are naturally very weak have hardly any of it. 3d. Alkohol is much less powerful in producing this effect, though it may be highly concentrated. It contracts, however, the texture of parts, which it condenses and even twists. So that those who preserve anatomical specimens, find it necessary to dilute the alkohol. 4th. The neutral salts, after being moistened by the humidity of animal substances, condense and harden them wonderfully after the lapse of a considerable length of time. 5th. When the air has taken away, by drying, the aqueous particles of the solids, these continuing exposed to its action, contract, wrinkle, and twist in a slow and gradual manner. 6th. The alkalies, however strong they may be employed, do not produce any kind of horny hardening. 7th. Water appears to act in a manner opposite to this horny hardening; it dilates, spreads the organs by maceration, and separates their particles. It is when it is combined with much caloric that it produces horny hardening. This phenomenon takes place at some degrees below boiling, and is very remarkable at that point.

The different agents of which I have just spoken, produce, then, two species of horny hardening: 1st. the first is prompt, sudden, almost like the motion which results from the irritation of a living muscle: 2d. the other slow, gradual, and even insensible. Fire and the strong acids are in a special manner the agents of the first. The action of the neutral salts, of the air, of alkohol, principally produce the second.

These two species differ very much in their results. The state to which the first reduces the organ, is soon changed if the hardening cause continues. 1st. Fire continuing to act upon the solids, reduces them to a hard and coaly mass. 2d. Boiling water, after a length of time, destroys by degrees the hardness the solids had suddenly acquired, by being plunged into it. As the hardness diminishes, the effect of the boiling increases, and it arrives at the greatest extent, when the solid, having lost all consistence, becomes pulpy. 3d. Animal organs that have been acted upon suddenly by the acids, and become consequently hard, soon grow soft and change into a true pulp. This double phenomenon, that is presented on the one hand by boiling, and on the other by the strong acids, has a great analogy, and seems to be derived from the same principle.

The slow and insensible horny hardening, the effect of the contact of neutral salts, such as alum, the muriate of soda, &c. of the air and of alkohol, offers a very different phenomenon from the first. It is not altered by the continued action of the cause that produced it, however long it may be; it does not soften in a slow and insensible manner, as it has hardened, but remains always firm and contracted.

Are these two species only different degrees of the same, or are they derived from separate principles? I know not. I have only observed, that when the living solids have undergone the slow and gradual horny hardening, they are still susceptible of the other. We know that after many years drying, animal textures are hardened, as in a recent state, by the action of fire; I have made the same observation with regard to boiling and the acids. Textures that have been contracted for a long time by alkohol and the neutral salts present the same phenomenon.

All animal textures are susceptible of sudden hardening, except the hair, the epidermis, and the nails; these, if we may so say, exhibit only the rudiments of it. In general the hardening is more sensible, in proportion as the fibrous texture predominates in the organs. Hence the muscles, the tendons, and nerves, are the most susceptible of it. The organs not fibrous, as the glands, show the least degree of it. The slow and insensible horny hardening is almost the same in every part. Both exist in textures deprived of animal contractility, of sensible organic contractility, and of contractility of texture, as well as in those which enjoy them in the highest degree. Thus the tendons, the aponeuroses, the bones, even when their calcareous substance has been removed by acids, may be hardened as well as the muscles and the skin. This single circumstance would suffice to distinguish the contractility arising from hardening from all others, if a variety of differences, which I shall point out hereafter, under the article of the muscles in particular, did not.

When a texture is suddenly hardened, it loses more than half its length, and becomes twisted in various ways. Taken suddenly from the acid or boiling water, it remains hardened; but if it is pulled, it becomes elongated, and then contracts again, when the force applied ceases, so that it has acquired a real elasticity by the process of hardening. This elasticity is remarkable in the tendons, nerves and muscles, which before this are absolutely destitute of it. This elasticity is not an effect of the slow and insensible hardening of alkohol and the neutral salts. By macerating for a length of time the organized textures, they gradually lose the power of contracting suddenly, which does not, however, entirely disappear, until the maceration has reduced the textures to mere pulp.

If the textures are softened by boiling, and stretched out to their original length, after having been hardened, this cannot be produced again by any agent that we may employ.

When the textures are in a state of putrefaction, they no longer possess this kind of contractility.

Slow and insensible hardening cannot take place during life; this is an insurmountable obstacle to it. But that which is sudden may, when its agents have overcome the resistance that vitality offers. Oftentimes we see the skin hardened by burns. When it is stripped of its epidermis, and a very strong acid is poured upon it, the same effect is produced as upon any other organ.

When a part has been hardened upon a living subject, it almost inevitably dies; it cannot be restored to the suppleness that it possessed before; suppuration separates it from the sound parts.

The fluids do not present the phenomenon of hardening, the fibrine only excepted. Separated from the blood, it crisps and contracts.

After what has been said, it is evident that the solids possess the faculty of contracting or shortening. This is brought into action in many different ways. During life it appears, 1st. in the influence of the nerves upon the voluntary muscles; this is animal contractility. 2d. In the involuntary muscles by the action of stimuli; this is sensible organic contractility. 3d. In the muscles, the skin, the cellular texture, the arteries, the veins, &c. from a want of extension. This is the contractility of texture, which is not found, or at least is very obscure, in many of the organs, as the nerves, the fibrous bodies, the cartilages, the bones, &c. 4th. By the action of fire, and the strong acids; this is the contractility of the horny hardening, and is general.

When the muscles are deprived of life, they lose the two first kinds of contractility; but the third remains with them as it does with all the organs that enjoy it. When they are dried or remain in water a little time, they lose that also; but the fourth still continues with them; it is the last that abandons the animal textures; it is perpetuated for a length of years. When I have exposed to the action of fire the cartilaginous parenchyma of bones found in cemeteries, they have become hardened. I am persuaded that this faculty would last for many ages, if we could preserve the organic textures.

Contractility is, then, a common and general property, inherent in all animal textures, but which, according to the manner that it is brought into action, presents essential differences, which divide it into many species, that have no analogy. It would certainly be impossible to avoid distinguishing the difference between the four species I have pointed out, and that insensible contraction, or kind of oscillation, which forms during life the insensible organic contractility, or tonic motions.

Among the causes that bring contractility into action, some belong, then, to life, others are independent of it, and are derived only from organization. All the organs are essentially contractile; but each of the causes which makes them contract acts only upon this or that texture: the horny hardening alone has a general effect.

VI. Observations upon the organization of animals.

The properties, whose influence we have just analyzed, are not absolutely inherent in the particles of matter that are the seat of them. They disappear when these scattered particles have lost their organic arrangement. It is to this arrangement that they exclusively belong; let us treat of it here in a general way.

All animals are an assemblage of different organs, which, executing each a function, concur in their own manner, to the preservation of the whole. It is several separate machines in a general one, that constitutes the individual. Now these separate machines are themselves formed by many textures of a very different nature, and which really compose the elements of these organs. Chemistry has its simple bodies, which form, by the combinations of which they are susceptible, the compound bodies; such are caloric, light, hydrogen, oxygen, carbon, azote, phosphorus, &c. In the same way anatomy has its simple textures, which, by their combinations four with four, six with six, eight with eight, &c. make the organs. These textures are, 1st. the cellular; 2d. the nervous of animal life; 3d. the nervous of organic life; 4th. the arterial; 5th. the venous; 6th. the texture of the exhalants; 7th. that of the absorbents and their glands; 8th. the osseous; 9th. the medullary; 10th. the cartilaginous; 11th. the fibrous; 12th. the fibro-cartilaginous; 13th. the muscular of animal life; 14th. the muscular of organic life; 15th. the mucous; 16th. the serous; 17th. the synovial; 18th. the glandular; 19th. the dermoid; 20th. the epidermoid; 21st. the pilous.

These are the true organized elements of our bodies. Their nature is constantly the same, wherever they are met with. As in chemistry, the simple bodies do not alter, notwithstanding the different compound ones they form. The organized elements of man form the particular object of this work.

The idea of thus considering abstractedly the different simple textures of our bodies, is not the work of the imagination; it rests upon the most substantial foundation, and I think it will have a powerful influence upon physiology as well as practical medicine. Under whatever point of view we examine them, it will be found that they do not resemble each other; it is nature and not science that has drawn the line of distinction between them.

1st. Their forms are every where different; here they are flat, there round. We see the simple textures arranged as membranes, canals, fibrous fasciÆ, &c. No one has the same external character with another, considered as to their attributes of thickness or size. These differences of form, however, can only be accidental, and the same texture is sometimes seen under many different appearances; for example, the nervous appears as a membrane in the retina, and as cords in the nerves. This has nothing to do with their nature; it is then from the organization and the properties, that the principal differences should be drawn.

2dly. There is no analogy in the organization of the simple textures. We shall see that this organization results from parts that are common to all, and from those that are peculiar to each; but the common parts are all differently arranged in each texture. Some unite in abundance the cellular texture, the blood vessels and the nerves; in others, one or two of these three common parts are scarcely evident or entirely wanting. Here there are only the exhalants and absorbents of nutrition; there the vessels are more numerous for other purposes. A capillary net-work, wonderfully multiplied, exists in certain textures, in others this net-work can hardly be demonstrated. As to the peculiar part, which essentially distinguishes the texture, the differences are striking. Colour, thickness, hardness, density, resistance, &c. nothing is similar. Mere inspection is sufficient to show a number of characteristic attributes of each, clearly different from the others. Here is a fibrous arrangement, there a granulated one; here it is lamellated, there circular. Notwithstanding these differences, authors are not agreed as to the limits of the different textures. I have had recourse, in order to leave no doubt upon this point, to the action of different re-agents. I have examined every texture, submitted them to the action of caloric, air, water, the acids, the alkalies, the neutral salts, &c. drying, putrefaction, maceration, boiling, &c. the products of many of these actions have altered in a different manner each kind of texture. Now it will be seen that the results have been almost all different, that in these various changes, each acts in a particular way, each gives results of its own, no one resembling another. There has been considerable inquiry to ascertain whether the arterial coats are fleshy, whether the veins are of an analogous nature, &c. By comparing the results of my experiments upon the different textures, the question is easily resolved. It would seem at first view that all these experiments upon the intimate texture of systems, answer but little purpose; I think however that they have effected an useful object, in fixing with precision the limits of each organized texture; for the nature of these textures being unknown, their difference can be ascertained only by the different results they furnish.

3dly. In giving to each system a different organic arrangement, nature has also endowed them with different properties. You will see in the subsequent part of this work, that what we call texture presents degrees infinitely varying, from the muscles, the skin, the cellular membrane, &c. which enjoy it in the highest degree, to the cartilages, the tendons, the bones, &c. which are almost destitute of it. Shall I speak of the vital properties? See the animal sensibility predominant in the nerves, contractility of the same kind particularly marked in the voluntary muscles, sensible organic contractility, forming the peculiar property of the involuntary, insensible contractility and sensibility of the same nature, which is not separated from it more than from the preceding, characterizing especially the glands, the skin, the serous surfaces, &c. &c. See each of these simple textures combining, in different degrees, more or less of these properties, and consequently living with more or less energy.

There is but little difference arising from the number of vital properties they have in common; when these properties exist in many, they take in each a peculiar and distinctive character. This character is chronic, if I may so express myself, in the bones, the cartilages, the tendons, &c.; it is acute in the muscles, the skin, the glands, &c.

Independently of this general difference, each texture has a particular kind of force, of sensibility, &c. Upon this principle rests the whole theory of secretion, of exhalation, of absorption, and of nutrition. The blood is a common reservoir, from which each texture chooses, that which is adapted to its sensibility, to appropriate and keep it, or afterwards reject it.

Much has been said since the time of Bordeu, of the peculiar life of each organ, which is nothing else than that particular character which distinguishes the combination of the vital properties of one organ, from those of another. Before these properties had been analyzed with exactness and precision, it was clearly impossible to form a correct idea of this peculiar life. From the account I have just given of it, it is evident that the greatest part of the organs being composed of very different simple textures, the idea of a peculiar life can only apply to these simple textures, and not to the organs themselves.

Some examples will render this point of doctrine which is important, more evident. The stomach is composed of the serous, organic muscular, mucous, and of almost all the common textures, as the arterial, the venous, &c. which we can consider separately. Now if you should attempt to describe in a general manner, the peculiar life of the stomach it is evidently impossible that you could give a very precise and exact idea of it. In fact the mucous surface is so different from the serous, and both so different from the muscular, that by associating them together, the whole would be confused. The same is true of the intestines, the bladder, the womb, &c.; if you do not distinguish what belongs to each of the textures that form the compound organs, the term peculiar life will offer nothing but vagueness and uncertainty. This is so true, that oftentimes the same textures alternately belong or are foreign to their organs. The same portion of the peritoneum, for example, enters or does not enter, into the structure of the gastric viscera, according to their fulness or vacuity.

Shall I speak of the pectoral organs? What has the life of the fleshy texture of the heart in common with that of the membrane that surrounds it? Is not the pleura independent of the pulmonary texture? Has this texture nothing in common with the membrane that surrounds the bronchia? Is it not the same with the brain in relation to its membranes, of the different parts of the eye, the ear, &c.?

When we study a function, it is necessary carefully to consider in a general manner, the compound organ that performs it; but when you wish to know the properties and life of this organ, it is absolutely necessary to decompose it. In the same way, if you would have only general notions of anatomy, you can study each organ as a whole; but it is essential to separate the textures, if you have a desire to analyze with accuracy its intimate structure.

VII. Consequences of the preceding principles relative to diseases.

What I have been saying leads to important consequences, as it respects those acute or chronic diseases that are local; for those, which like most fevers, affect almost simultaneously every part, cannot be much elucidated by the anatomy of systems. The first then will engage our attention.

Since diseases are only alterations of the vital properties, and each texture differs from the others in its properties, it is evident there must be a difference also in the diseases. In every organ then, composed of different textures, one may be diseased, while the others remain sound; now this happens in a great many cases; let us take the principal organs, for example.

1st. Nothing is more rare than affections of the mass of the brain; nothing is more common than inflammation of the tunica arachnoides that covers it. 2d. Oftentimes one membrane of the eye only is affected, the others preserving their ordinary degree of vitality. 3d. In convulsions or paralysis of the muscles of the larynx, the mucous surface is unaffected; and on the other hand the muscles perform their functions as usual in catarrhs of this surface. Both these affections are foreign to the cartilages, and vice versa. 4th. We observe a variety of different alterations in the texture of the pericardium, but hardly ever in that of the heart itself; it remains sound while the other is inflamed. The ossification of the common membrane of the red blood does not extend to the neighbouring textures. 5th. When the membrane of the bronchia is the seat of catarrh, the pleura is hardly affected at all, and reciprocally in pleurisy the first is scarcely ever altered. In peripneumony, when an enormous infiltration in the dead body shows the excessive inflammation that has existed during life in the pulmonary texture, the serous and mucous surfaces often appear not to have been affected. Those who open dead bodies know that they are frequently healthy in incipient phthisis. 6th. We speak of a bad stomach, a weak stomach; this most commonly should be understood as applying to the mucous surface only. Whilst this secretes with difficulty the nutritive juices, without which digestion is impaired, the serous surface exhales as usual its fluid, the muscular coat continues to contract, &c. In ascites, in which the serous surface exhales more lymph than in a natural state, the mucous oftentimes performs its functions perfectly well. &c. 7th. All authors have said much of the inflammation of the stomach, the intestines, the bladder, &c. For myself I believe that this disease rarely ever affects at first the whole of any of these organs, except in the case where poison or some other deleterious substance acts upon them. There are for the mucous surface of the stomach and intestines, acute and chronic catarrhs, for the peritoneum serous inflammations, perhaps even for the layer of organic muscles that separates the two membranes, there is a particular kind of inflammation, though we have as yet hardly any thing certain upon this point; but the stomach, the intestines, and the bladder are not suddenly affected with these three diseases. A diseased texture can affect those near it, but the primitive affection seizes only upon one. I have examined a great number of bodies in which the peritoneum was inflamed either upon the intestines, the stomach, the pelvis, or universally; now very often when this affection is chronic, and almost always when it is acute, the subjacent organs remain sound. I have never seen this membrane exclusively diseased upon one organ, while that of the neighbouring ones remain untouched; its affection is propagated more or less remotely. I know not why authors have hardly ever spoken of its inflammation, and have placed to the account of the subjacent viscera that which most often belongs only to this. There are almost as many cases of peritonitis as of pleurisy, and yet while these last have been particularly noticed the others are almost entirely overlooked. Oftentimes that part of the peritoneum corresponding to an organ, is much inflamed; we see it in the case of the stomach; we observe especially after the suppression of the lochia or the menses, that it is the portion that lines the pelvis that is first affected. But soon the affection becomes more or less general; at least examinations after death prove it satisfactorily. 8th. Certainly the acute or chronic catarrh of the bladder, or womb even, has nothing in common with the inflammation of that portion of the peritoneum corresponding with these organs. 9th. Every one knows that diseases of the periosteum have oftentimes no connexion with the bone, and vice versa, that frequently the marrow is for a long time affected, while both the others remain sound. There is no doubt that the osseous, medullary and fibrous textures have their peculiar affections which we shall not confound with the idea we may form of the diseases of the bones. The same can be said of the intestines, of the stomach, &c. in relation to their mucous, serous, muscular textures, &c. 10th. Though the muscular and tendinous textures are combined in a muscle, their diseases are very different. 11th. You must not think that the synovial is subject to the same diseases as the ligaments that surround it, &c.

I think the more we observe diseases, and the more we examine bodies, the more we shall be convinced of the necessity of considering local diseases, not under the relation of the compound organs, which are rarely ever affected as a whole, but under that of their different textures, which are almost always attacked separately.

When the phenomena of diseases are sympathetic, they follow the same laws as when they arise from a direct affection. Much has been said of the sympathies of the stomach, the intestines, the bladder, the lungs, &c. But it is impossible to form an idea of them, if they are referred to the organ as a whole, separate from its different textures. 1st. When in the stomach, the fleshy fibres contract by the influence of another organ and produce vomiting, they alone receive the influence, which is not extended either to the serous or mucous surfaces; if it were, they would be the seat, the one of exhalation, the other of sympathetic exhalation and secretion. 2d. It is certain that when the action of the liver is sympathetically increased, so that it pours out more bile, the portion of peritoneum that covers it does not throw out more serum, because it is not affected by it. It is the same of the kidney, the pancreas, &c. 3d. For the same reason, the gastric organs upon which the peritoneum is spread, do not partake of the sympathetic influences that it experiences. I shall say as much of the lungs in relation to the pleura, the brain in relation to the tunica arachnoides, the heart to the pericardium, &c. 4th. It is undeniable that in all sympathetic convulsions, the fleshy texture is alone affected, and that the tendinous is not so at all. 5th. What has the fibrous membrane of the testicles in common with the sympathies of its peculiar texture? 6th. No doubt a number of sympathetic pains that we refer to the bones, are seated exclusively in the marrow.

I could cite many other examples to prove, that it is not this or that organ which sympathizes as a whole, but only this or that texture in the organs; besides, this is an immediate consequence of the nature of sympathies. In fact the sympathies are but aberrations of the vital properties; now these properties vary according to each texture; the sympathies of these textures then would do the same.

Observe what takes place in fever, accompanying the different kinds of inflammation. That attending the mucous is slight, that with the serous severe, and that with the cutaneous has the peculiar character of showing itself some days before the eruption, as has been noticed by Pinel. If we attentively observe the fever which attends the inflammations of all the systems, we shall find as many differences, as many peculiar characters, as there are systems. Whence does this arise? From the difference of the relations that unite the heart to each kind of texture; now this difference of relations is the result of the difference of the vital forces peculiar to each.

Observe the itch, herpes, cancer, venereal disease, &c. when they have ceased to be local affections, they spread themselves universally; they alternately attack different textures, according to the relation which they have with the organic sensibility of these textures. But it is almost always separately that they attack them; an organ is never as a whole influenced by them in all its parts. What do I say? If two of these diseases exist at the same time, one seizes upon one texture, the other upon a different one of the same organ. Thus the stomach, the intestines, the lungs, &c. can be attacked by two different diatheses, and each will be independent of the other, because each will be fixed upon a different texture, one upon the mucous, for example, the other upon the serous, &c.

Let us not, however, exaggerate this independence of the textures of the organs in diseases, lest experience should contradict us. We shall see that the cellular system is oftentimes a medium of communication, not only from one texture to another in the same organ, but from one organ to a neighbouring one. Thus in many chronic diseases, all the parts of the same organ are gradually changed, and at the examination of this organ after death, the whole of it appears to have been affected, though one of its textures only was so at first. In the cancer of the breast, you find at first only a small gland that rolls under the finger; finally the glandular, the cellular, and even the cutaneous textures are confounded in one common cancerous mass. Cancer of the stomach, the intestines, the penis, &c. follows the same course. Observe phthisis, exhibiting in the beginning some small tubercles in the pulmonary texture, at length invading oftentimes the pleura, the bronchial membrane, &c. How little soever you may examine bodies with a view to the same chronic disease, and at different periods, you will be convinced of the truth of this assertion, viz. that a texture being at first affected in an organ, communicates its affection gradually to others, and that you will be deceived in judging of the primitive seat of the disease, if you attempt to determine it from the parts found affected at the time of the examination.

In acute diseases, continuity is oftentimes sufficient to explain the different symptoms that appear in textures that are not affected. The peritoneal coat only being inflamed, vomiting is produced. We cough and sometimes expectorate considerably when the pleura alone is diseased. Delirium comes on when the tunica arachnoides is inflamed, though the intellectual functions are not connected with it. Frequently the diseases of the pericardium are sufficient to disturb the motion of the heart, &c. We cannot deny after this, that oftentimes an alteration in one of the textures alone of an organ is sufficient to disturb the functions of all the others; but still it is in one only, that the primitive source of the evil exists.

I now pass to some other considerations relative to the influence of the anatomy of systems in diseases.

Since every organized texture has every where the same arrangement; since, whatever be its situation, it has the same structure and the same properties, it is evident that its diseases must be every where the same. It makes no difference, that the serous texture is connected with the brain by the tunica arachnoides, with the lungs by the pleura, with the heart by the pericardium, with the gastric viscera by the peritoneum, &c. every where it is inflamed in the same manner; every where dropsies take place in the same way; every where it is subject to a species of eruption of little whitish tubercles, like the miliary, of which I believe there has been no description, but which deserves great attention; I have already many times observed this peculiar eruption of the serous texture, which is generally of a chronic character, like most of the cutaneous eruptions; I shall speak of it hereafter. Whatever may be the organ that the mucous texture invests, its affections have in general the same character, excepting the difference only that arises from variety of structure. I will say the same of the fibrous, cartilaginous textures, &c. Mr. Pinel appears to me to have done much for the art, in being the first who arranged inflammations in the order of the systems, and embracing in one general view all those of the same system, whatever may be the organs in which it is found.

There are always two orders of symptoms in inflammations; 1st. those that belong to the nature of the diseased textures; 2d. those which depend upon the affected organ, in which the inflammation exists. For example, the kind of pain, the nature of the accompanying fever, the duration, the termination, &c. are almost always the same, whatever serous surface is affected. But difficulty of breathing, dry cough, &c. prove it to be the pleura; diarrhoea, constipation, vomiting, &c. that it is the peritoneum; injury of the intellectual functions, that it is the tunica arachnoides; irregular pulse, that it is the pericardium, &c. The first belong to the whole class, the second set of symptoms is confined exclusively to this or that particular sort; now the second are, if we may so say, accessory, depending upon the proximity of the affected texture with some other texture. The first are particularly important.

Medicine has yet much to do, in its researches upon the inflammation of the different textures. We are well acquainted with that of the cellular, the cutaneous, the serous, and the mucous; but that of the others is very obscure. It is yet to be ascertained, which is attacked, the fibrous or muscular, in rheumatism. I am inclined to think that it is the first. Almost every thing remains to be known in the cartilaginous, the synovial, the arterial, the venous, &c. as it respects their inflammatory phenomena.

In making these researches, it will be necessary to establish one important distinction; that is, 1st. that certain textures, as the osseous, the muscular of animal life, &c. are precisely the same in all the organs in which they are found, and consequently that their diseases must be the same; 2d. that others, as the cutaneous, the serous, the mucous, &c. experience, according to the organs to which they belong, some variety of structure and vital properties, which necessarily modify the general phenomena of the class of diseases that belong to these textures; 3d. that others, as the glandular, the muscular of organic life, &c. are very different in each organ; and that their general symptoms and class of diseases must consequently differ considerably.

After having shown most of the local diseases, as affecting almost always, not an individual organ, but some texture in an organ, it is necessary to show the differences they present according to the textures they affect. As under each system, this subject will be treated more or less fully, I shall only refer to it here.

We shall see, then, that pain is modified differently in each texture, according to the degree of sensibility that it possesses. No one excites the same sensations as the others when it is inflamed. Compare the burning of erisypelas with the throbbing of phlegmon, the pain of rheumatism with that of inflamed lymphatic glands, &c. We shall see also that the sense of heat, developed in each inflamed texture, has a particular character; here it is sharp and biting, there like the feeling produced by fire, &c. There are two general causes that produce a variation in the symptoms of diseases: 1st. the nature of the affected texture; thus, as I have just said, the inflammation of each produces a different kind of suffering. 2d. The nature of the disease; we know that cancer, whatever texture it may affect, has a pain that is peculiar to it; that syphilis and scurvy have also a peculiar character, that is, however, modified in a slight degree in each texture.

The difference of textures not only modifies the symptoms, but affects the duration of them also. Nothing in medicine is more vague, in this point of view, than the terms acute and chronic, in relation to inflammations of the different textures. Most commonly they run their course rapidly in the dermoid, cellular, serous, mucous textures, &c.; on the other hand, they are slow in the bones, the cartilages, and the fibro-cartilages. If we apply this distinction to the same texture, it is very well; thus there are catarrhs, serous and cutaneous inflammations, &c. that are acute and chronic. But if we generalize it, it cannot be understood. A catarrh would be chronic if it lasted two months; but this is the common term of an acute inflammation of the bones; a chronic one continues for a whole year or more. Cutaneous, mucous wounds, &c. last only five or six days if they heal by the first intention; while it requires thirty or forty for a bone, a cartilage, &c. to be cicatrized by the juxta-position of its different parts. A disease cannot be classed, then, by its duration, as an acute or chronic one, except in relation to the same system; when we describe it then in a general way, this distinction becomes void.

Physicians consider abstractedly almost all diseases. When they speak of inflammation they describe the redness, swelling, throbbing and pain, as general attributes, always uniform. If of suppuration, they take for a general standard that of the cellular texture, in phlegmon, without thinking that it is only one of the modifications of suppuration and its product. The same may be said of gangrene, scirrhus, &c. Nothing is more vague and uncertain than the general ideas that are given concerning a disease; they scarcely agree in one or two of the textures.

It is not only the history of diseases that the anatomy of systems will elucidate; it will change in part the method of treating morbid anatomy. Morgagni, to whom we owe so much in this respect, and many others, to whom the art is indebted, have adopted the general arrangement used in descriptions. They have examined the diseases of the head, the chest, the abdomen, and the extremities. In following this method, they can only form to themselves a general idea of the alterations common to all the textures. The ideas are necessarily too much contracted, when there is presented only an insulated part of a system, which is composed of a great many others. If, besides this, you obtain a general knowledge of the affections of each system, you must bear in mind, with regard to each, the general ideas concerning the affections of the parts they compose.

It appears to me to be infinitely more simple to consider at first all the affections common to each system, and then to observe what every organ has peculiar to itself in the part that it occupies.

I divide, then, morbid anatomy into two great parts. The first contains the history of the alterations common to each system, whatever may be the organ in the structure of which it is concerned, or whatever may be the place it occupies. It is necessary to show at first the different alterations of the cellular, arterial, venous, nervous, osseous, muscular, mucous, serous, synovial, glandular, cutaneous textures, &c. to examine the kind of inflammation, suppuration, gangrene, &c. peculiar to each; to speak of the different enlargements of which they are susceptible, the changes in their nature, which they undergo, &c. Some, as the mucous, the cutaneous, the serous, the glandular, &c. afford in this respect an immense field to morbid anatomy. The others, as the fibrous, the nervous, the muscular, &c. are more rarely changed in their texture. We shall see hereafter that nutrition alone is performed in these, and that the others are particularly the seat of exhalation, absorption, secretion, &c. functions which suppose much energy in the insensible contractility and organic sensibility, which are connected with all the alterations of texture.

After having thus pointed out the alterations peculiar to each system, in whatever organ it is found, an examination should be made of the diseases peculiar to each region; as those of the head, the chest, the abdomen, and the extremities, after the common method. Here they may be divided, 1st. into diseases which can especially affect an organ as a whole, and not one of its textures alone, which is very rare. 2d. Into the characters peculiar to each portion of this or that texture; for example in the head, the peculiar symptoms which are seen in diseases of the serous surface of the tunica arachnoides, those in affections of the mucous surface of the pituitary membrane, &c.

This course is incontestably the most natural, though, as in all divisions in which we wish to copy nature, there are many cases which it almost excludes.

It seems to me that we live at a period, when morbid anatomy should take a higher stand. This science is not only that of organic derangements, that take place slowly, as the principles or consequences of chronic diseases, it consists in the examination of all the alterations our organs can undergo, at any period in which we may observe their diseases. With the exception of certain kinds of fevers and nervous affections, every thing in pathology is within the province of this science. How weak appears the reasoning of many great physicians, when we examine it, not in their works, but on the dead body. Medicine was for a long time excluded from the circle of the exact sciences; it will have a right to be associated with them, at least in the diagnostics of diseases, when we shall every where unite to accurate observation, an examination of the changes our organs undergo. This course is beginning to be that of all rational minds; it will without doubt soon be general. What is observation worth, if we are ignorant of the seat of the disease? You may take notes, for twenty years, from morning to night at the bedside of the sick, upon the diseases of the heart, the lungs, the gastric viscera, &c. and all will be to you only a confusion of symptoms, which, not being united in one point, will necessarily present only a train of incoherent phenomena. Open a few bodies, this obscurity will soon disappear, which observation alone would never have been able to have dissipated.

VIII. Remarks upon the classification of functions.

The plan that I have followed in this work, is not the most favourable to the study of the functions. Many of them, such as digestion, respiration, &c. would find no place here, because they do not belong especially to the simple systems, but to a combination of them, an union of many systems, and even of many organs. Thus what I have said upon the functions, is introduced only incidentally in this work, the particular object of which is the analysis of the different simple systems that form the compound organs. However, as some would wish to connect the different facts of physiology that it contains, with a physiological classification, I will now explain that which I have adopted in my course of lectures.

We know how different the kinds of classification are. The ancient division, into animal, vital, and natural functions, rests upon so weak a foundation, that a methodical superstructure could not be raised upon it. Vicq d'Azyr has substituted one for it which offers hardly any more advantages, as it separates phenomena that are connected, and changes into functions, properties, such as sensibility, irritability, &c. Since this author, others have made divisions which are not more methodical, and are equally removed from the natural arrangement of the phenomena of life.

I have endeavoured, as far as possible, in classing the functions, to follow the path marked out by nature herself. I have laid, in my work upon Life and Death, the foundations of this classification, which I pursued before I published this work. Aristotle, Buffon, &c. have seen in man two kinds of functions, one which connects him with external bodies, the other, which serves for his nourishment. Grimaud brought forward again this idea, which is as great as it is true, in his course of physiology and in his memoir upon nutrition; but by considering it in too general a manner, he did not analyze it with sufficient exactness, he ranked among the external functions, only sensation and motion, he did not describe the brain as the centre of these functions, nor place the voice among them, which is however one of the great means of communication, with the bodies that surround us. He did not analyze more accurately the internal functions. He did not point out their connexion in the elaboration of nutritive matter, where each works in its turn, if I may so express myself; nor show the distinctive characters, which separate generation from all the other functions relating to the individual alone. Besides, the distinction of internal and external functions was only presented as a general sketch in his Memoir upon Nutrition, and not as a means of classification. He did not avail himself of it, in the division of the functions, in his lectures, of which many manuscripts arranged by himself, are to be met with at the present time; in these he examined, 1st. osteogony, which was treated at much length; 2d. the action of the muscles; 3d. the action of the vessels or the circulation; 4th. generation; 5th. the action of the organs of the senses; 6th. the action of the brain and nerves; 7th. digestion; 8th. secretion; 9th. respiration, &c. From this it may be perceived, that Grimaud, like preceding authors, mixed together all the functions without referring them to certain general heads.

In reflecting upon the division pointed out above, I soon saw that it was not only one of those general views, one of those great outlines, that are oftentimes made by men of genius who cultivate physiology, but that it might become the permanent basis of a methodical classification. To come at this classification I observed that it was necessary at first to refer all the functions to two great classes, one relating to the individual, the other to the species; that these two classes had nothing in common, but the general connexion that unites all the phenomena of living bodies; but a variety of distinctive attributes characterize them, which cannot be separated from them.

These two first classes being rigorously defined, and their limits established by nature, I sought to discover in each, orders equally natural; this was easy in the functions relating to the individual. In fact, this was the place for the general outline of Aristotle and Buffon; but it was not to be presented in too general a manner; the nature and connexion of the functions peculiar to each order, were to be accurately assigned.

I called the order of functions that connects us with external bodies, animal life, thus indicating that this order belongs alone to animals, that it is more with them than with vegetables, and that it is the addition of these functions that particularly distinguishes them from vegetables. I called organic life, the order that serves for the constant composition and decomposition of our bodies, because this life is common to all organized beings, vegetables as well as animals; and because the only condition of enjoying it is organization; so that it forms a boundary between organic and inorganic bodies, as animal life serves to separate the two classes that form the first.

Animal life is composed of the action of the senses which receive impressions, of the brain which perceives them, reflects, and wills, of the voluntary muscles and larynx that execute this volition, and of the nerves which are the agents of transmission. The brain is truly the central organ of this life. Digestion, circulation, respiration, exhalation, absorption, secretion, nutrition, calorification, compose organic life, which has the heart for its principal and central organ.

I place calorification here, because it is evident from what I have said under the article upon the capillary systems, that it is a function analogous to secretion, exhalation and nutrition. It is truly a separation of combined caloric, from the mass of blood. It is, if the expression is preferred, a secretion or exhalation of that fluid in every part of the body. I have not even at present given this place to heat in my physiological classification: but in reflecting upon the method of its production, it will be seen that it ought to have it.

The two orders of the first class being established, it was easy to assign those of the second, which are three in number: 1st. functions belonging to the male; 2d. those belonging to the female; 3d. those arising from an union of the two sexes and the product of this union; these are the three orders.

Such is the classification that I made in my Lectures on Physiology; it has evidently nothing in common with any of those that are found in physiological works; and if you reflect upon it a little, it will appear I think infinitely preferable to any of them. Observe in fine, that each class and each order have general and characteristic attributes that particularly distinguish them, and which being applicable to all the functions of that order, mark a difference between them and all the functions of any other order. I have pointed out moreover the distinctive attributes of animal and of organic life; I have shown that the organs of one are symmetrical, those of the other irregular; that there is a harmony in the functions of the first, a discordance in those of the second; that one commences sooner and terminates later, &c.

I have demonstrated, that the cerebral nerves belong especially to animal life, the nerves of the ganglions to the organic, which appears to me to be a remarkable difference, and which has induced me to make two systems of the nerves, that anatomists have united in one. The first, belonging to animal life, is composed of the cerebral nerves, the other to organic, is formed of the nerves of the ganglions, or what is commonly called the great sympathetic.

But it is the vital powers especially that distinguish one life from another. I have shown that one kind of sensibility and contractility belongs to animal life, and another to organic. Now as these vital properties are the principle of the functions, it is evident that the division of these properties demonstrates that that of the two lives is not an abstraction, but that it is nature herself that has fixed the limits, since she has made particular properties for each.

It is impossible to form a precise idea of the vital properties, without admitting the division I have made. How many disputes there have been, upon the subject of sensibility! Not one of them would have taken place, if the attributes of animal life had been properly distinguished from those of the organic. Certainly no one will hereafter confound in one view, as frequently has been done, the faculty that the heart has of being sensible to the entrance of the blood, without transmitting that impression, and the faculty that the skin, the other senses, the nerves, &c. have, not only of feeling the impression of external bodies, but of transmitting it to the brain, so that the sensation may be perceived.

If you include under one common name of irritability, the motions of muscles that contract only by stimuli, and those which the cerebral influence puts in action, it is impossible that you should be understood.

There has been much discussion during the last age, upon the point, whether sensibility is the same as contractility, or if these two properties can be separated. Each of the two opinions seem to have rested upon an equally solid foundation. But all these disputes will be done away, by admitting the distinction I have made in the vital properties. 1st. In animal life, then, it is evident, that contractility is not a necessary consequence of sensibility; thus frequently external objects make for a long time an impression upon us, and yet the voluntary muscles remain unmoved. 2d. On the other hand, in organic life, these two properties are never separated. In the involuntary motions of the heart, the stomach, the intestines, &c. there is first an excitement of the organic sensibility, and then an action of the sensible organic contractility. In the same manner, in the motions necessary to secretion, exhalation, &c. when the organic sensibility has been brought into action, immediately insensible organic contractility takes place. It is that they may be studied better, and appreciated more accurately, that in organic life, I separate these two kinds of contractility from sensibility. In the natural state they are inseparable. Hence why the passive sympathies of animal sensibility are very different from those of animal contractility, and make two distinct classes, whilst the passive sympathies of organic sensibility can never be separated from the corresponding contractilities. We suffer by sympathy, and are sympathetically convulsed in a distinct manner; these two things are almost always separate. On the contrary, sensation and motion in the organic sympathies are inseparable.

I could prove by many examples, that all the disputes, and all the diversities of opinion, upon the subject of the vital properties, proceed only from this cause, that those which preside over the functions of one life, have not been distinguished from those which put into action the functions of the other.

Let us return to my physiological division; I will now give a table of it, which, presenting it under one point of view, will give a more precise idea of the classification. This table comprehends, 1st. the prolegomena of the science; 2d. the exposition of the functions. In the prolegomena, every thing is referred to two great considerations; on the one hand to organic texture, described in a general manner, and on the other to life, considered in relation to its great attributes.