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Meckel JF. Handbook of Pathological Anatomy (Handbuch der pathologischen Anatomie) Vol. 1. (1812) Leipzig.

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Handbook of Pathological Anatomy Volume I (1812)

General Anatomy. Part I

I. Anatomy is the science of the organic form. This term is not very convenient, as it suggests only one of the numerous means employed to attain a knowledge of the organism ; hence, the terms zoography, physiology organography, and morphology, have been proposed as substitutes for it ; but as the word anatomy is sanctioned by long usage, and does not retard the continual progress of the science, it may be retained without inconvenience, and probably will be always used.

That series of practical rules by which we gain a knowledge of the organism, constitutes the art of anatomy. Its relations with anatomy are then those which exist between the means and the end.

II. The particulars of the organic form are,

1 . The external form, which may also be called the configuration ; it is determined by the relations which exist between the three dimensions.

2. The inner fonn or the texture, (textura,) the maimer in which the body or its parts are composed. The term stnicture is also given arbitrarily to the composition of the whole body, inasmuch as it is formed of large parts, while texture is apphed to the composition of these parts, since they themselves are produced by the union of parts still smaller.

3. The size.

4. The color.

5. The physical properties, the degree of cohesion, of elasticity, &c.

6. The relation of locality of one part in regard either to the others, or to the whole body, and consequently, a. its situation, its place in the organism ; b. its mode of connection with the parts adjacent.

In the sketch of the organic form, we consider more or less completely.

Introduction

1 . The Chemical composition, and

2. The properties and actions of the organisms, in order to present as complete a view as possible of all their characteristics.

In fact, we may say that anatomy is to a certain extent the historical part of physiology ; hence it would be convenient to consider these two sciences as forming but one, and to place them first in all books.

III. The subject of anatomy is extremely varied ; it may then be presented in a great many different forms.

IV. Thus:

1 . The science of the organization may comprehend a greater or less number of different organisms. The subject of anatomy, in general, is to make loiown the form of all the organs ; but the objects are so many and various, that it has been subdivided into phytotomy, or vegetable anatomy, and zootomy, or comparative anatomy. {1) In

(1) The unity of the organic composition, the most important fact of animated nature, is now admitted by all enlightened naturalists. The meditative Greeks discovered it ; but when they studied it in detail, they objected to what were termed its numerous exceptions. This difference arose from the fact that Aristotle, and after him Galen, who have been followed by all anatomists, founded comparative anatomy on the unity of functions, because they knew not how to proceed, except upon perfect organs, exercising determinate functions, and did not recognize identities, except in pursuing the insensible gradations of forms. An example will show better than abstract remarks the defect of this method, which prevented the unity of anatomy from being recognized, although that of the organic composition was admitted, and which determined the naturalists to make as many distinct systems of anatomy as they could perceive different characters. Take, for instance, the four limbs of a cat; they carry the trunk; they are the organs of support; they are composed of moveable parts, which, put in action by the muscles, serve to move the trunk ; they are, then, the organs of Locomotion; they are terminated by moveable phalanxes, which extend and bend â€” these are the organs oiprehension, to seize and retain their prey ; finally, the last phalanx, which is naturally turned backward, can be brought in the saiiie direction with the others, so that the sharp nails, which terminate it, project â€” they are the means of attack and defense. Now, if we consider the four limbs of the ape, we find they are capable only of the first three functions ; they perform only the first two in the dog, and the second in the seal. Their anatomical relations are, however, the same. Anatomy demonstrates, in the limbs of the cat, of the ape, of the dog, and of the seal, the same bones, the same muscles, the same ligaments, the 'same envelops, and the same nails ; they differ only in slight modifications of form and size, to assist their uses. How then ought we to regard these forms, proportions, and functions

Impressed with these great principles, J. St. Hilaire discovered, that to attach to anatomy a philosophical and truly scientific character, we must neglect the organs themselves, their too fugitive forms, and various functions, and consider only the organic elements, which change or increase from new developments. In this manner he arrived at organic elements, which are, strictly speaking, the same, and discovered, that the functions of the organs are much modified, according as some of their parts vary in length and thickness. Such is the path pursued by this naturalist, to give a philosophical turn to anatomy. His doctrine is, in fact, that of Aristotle, but with this important distinction, which gives it the character of a real discovery : Aristotle did not recognize the analogy, except while the functions were preserved ; that is, he admitted no similarity when organs, composed of elements, employed these same elements, partly before, partly behind, or on the side ; in a word, directed them to other organs. Hence, a resemblance in form, and an equivalent destination, assured him that the organizations were identical : in short, he mistook the appearance only for the rule. J. St. Hilaire does not say that the organs, but the materials of which they are composed, are always the same. This distinction changes the state of the question entirely, for then the identity remains a genera! fact, even when the organs do not continue the same, as on leaving the classes. In fact, it is ordy when the connections and mutual relations of two parts are similar, that they are analogous according to the new theory, which attaches but a secondary importance to the different uses entailed by their newly acquired relations, and introduces for the first time in anatomy, the principle of the dissemination of the organism each of the two organized kingdoms, the science may treat particularly of a class, an order, a genus, or even a species. In fact, we must know the forms of all the species, to have a complete phytotomy or zootomy, and lastly, a complete anatomy.

2. The limits of anatomy may also be contracted or extended, because the organic form is not confined in each species by absolute rules, nor are all individuals formed after the same type. Thus :

a. Anatomy is not the same at all periods of life :

b. The two sexes differ from each other, at all ages, at least in the perfect species :

c. The species comprehend a greater or less number of varieties, of races.

There is then an anatomy of ages, sexes, and races :

These differences may be considered as regular, inasmuch as they are constant, and necessarily belong to organized bodies.

A second class of differences comprises the irregularities, so called either because they are not necessarily connected with the essential forms of organized bodies, and most of them arise more or less evidently by a departure of the formative act from the laws of formation, or because they endanger more or less imminently the existence of the organism.

Pathological anatomy treats of these aberrations from the primitive type.(l)

The anatomy of a species, to be complete, should comprise all the conditions above mentioned. We may, however, separate some of them from the rest, and consider them only tenais, â– which is so fertile in results ; by virtue of which these materials, when displaced, take on new actians, as do all those organs which have become rudimentary. Thus the doctrine of our learned compatriot is founded on the following : 1. That identity does not always depend upon the organs as a whole, but only on the materials of which each is composed. 2. That inquiries after identity should regard the mutual, necessary, and consequently invariable, dependence of the parts. 3. That the organic elements which touch, are, from their position, necessarily constrained to assist one another reciprocally. 4. 'Finally, that an organ, whether in its normal or pathological state, never possesses extraordinary activity, unless some other one of the same system, or of those connected with it suffers proportionally, and in the same ratio. J. St. Hilaire briefly terms these the four fundamental laws of every organic formation, theory of analogies, â€¢principle of connections, elective affinities of the organic elements, and balance of organs. Regarded in this new light, anatomy will change the view of physiology, and will finally allow it to rank among the sciences ; it will even have a direct influence upon the practice of medicine; for, first, it will establish general pathology on a rational foundation, and refer to a single principle the many facts observed by pathologists, although ignorant of the law which embraced them all ; secondly, it will teach us to mistrust the experiments on animals, in which we have hitherto confided implicitly. Many physicians draw conclusions from these experiments in regard to man, saying, â€œthe organs are the same, and consequently the functions must be similar.â€ A blow from the claw of a cat, or the tiny hand of a child, would lead to an opposite conclusion. The stomach of the dog is unique like that of man ; but an enlargement in the size of its parts would change the nature of its functions. Will the dog then vomit, as man does 1 Be careful how you conclude. F. T.

(1) Our idea of pathological anatomy would not be correct did we suppose, from the definition, it treated only of monstrosities, or of variations from the formative type ; for it makes us acquainted, also, with all the accidental alterations of the organic tissues produced by disease. Hence, to avoid all doubt, wc say, that it treats of all aberrations from the primitive type, congenital or accidental. F. T.

Tho differences of the first class are not generally excluded from works which treat of the form in its regular state. It is to be regretted that the periodical differences arising from age are not usually sufficiently appreciated, being often very wrongly separated more or less from the anatomy, and considered as branches of a science with which they have no connection. On the contrary, the study of the normal state is often separated from that of the anomalies. This is also AVTong ; first, because the line of distinction between the rule and the exception cannot always be exactly drawn. Secondly, because the anomaly is often a comment on the rule, and is a deviation only at the age when it is found. And finally, because, as anatomy proposes to give a complete view of the organic form, this end can be attained only by treating of every particular of this form.

V. Anatomy may be presented in very different forms. Sometimes it is thought sufficient to describe successively the organized bodies as a whole, and in detail ; sometimes general results are deduced from these isolated descriptions, in order to obtain directly a knowledge of the peculiarities which distinguish the different tissues which compose the organism, and the general laws according to which the organic form seems to have been produced.

Hence anatomy is divided into two parts, according as it treats of a single species of animals, or embraces all organized bodies, into general and special, or topographical anatomy.

The first comprises the general conditions of the organisms, and the union of the parts which form them ; the other is confined to their details. The first acquaints us with the different sijstems composing the organism, the other learns us the distinctions between the different parts of the same system. The former pertains rather to physiology.^ the latter to surgery ; but the second is indispensable to the physiologist, as the first is to the surgeon.

General Anatomy Sources

The sources of general anatomy, are all the works on general anatomy, and on physiology, as well as on the different branches of the former ; since we there find an exposition, more or less exact and complete, both of the general properties of the organic formation, as of those of each of the systems which unite to form the organism.

Under the first head we recommend several chapters of the first volume of Dumas {Principes de Physiologie, Paris, 1806 ;) under the second, Haller's {First lines of Physiology,) Bichat, {General Anatomy, Boston, 1822,) with Bedard's additions, and SÅ“mmering, {Lehre vom Baue des menschlichen Kcerpers, Frankfort, 1800.) The last is mentioned, principally, for the general conditions of most of the organic systems, particularly the bones, ligaments, muscles, nerves, and vessels.

In most of these works, the healthy and unhealthy state of the parts are considered at the same time, but without sajdng all that can be said upon the latter topic, and without always ascribing to it the importance it merits. Portal {Anatomie medicale, Paris, 1804,) has treated all the organized systems in both of these states on a good plan.

The French anatomists have, generally, described pathological alterations in their treatises before the writers of other natiops. Munroe's book {Outlines of the Anatomy of the Human Form, London, 1813) is an exception to this remark.

The principal treatises on the alterations of textures, and of the structure of the human body, and the most important for exact descriptions, and the great number of facts tending to establish the systems of pathological anatomy on a firm basis, are those of

Morgagni, {De cans, et sedibus morb.)

Baillie, {JMorbid Anatomy of the Human Body, 1793.)

Voigtei, {Handbuch der pathologischen Anatomie, Halle, 1804,) and

Mechel, {Handbuch der pathologischen Anatomie, Halle, 1813.)

The principal works upon each part of general anatomy wÃ¼l be mentioned hereafter, when treating of those parts.

General Anatomy Part II. General Laws of Formation

Â§ 1. The human body, as well as all those that resemble it, is composed of various parts, which have the mutual relations of preservation or of generation, and which reciprocally play the part of means and end, one with the other, and of which the ag^ 2 ^(b^ritely varied, have, for a result, life, and the preservation of formed by their union.

Â§ 2. These parts are so different va form, chemical composition, physical and vital powers, and the phenomena dependent upon them, that it is much easier to point out their differences, than their analogies. Nevertheless, when the thing is examined attentively, we can mention certain general qualities, in regard to all the conditions above, so that these considerable differences then seem to be only simple modifications of a single and even primitive type.

Â§ 3. The organic form, consequently also the human form, presents two points of view : 1st, its intimate composition, the texture of its parts' ; 2d, the external composition, the structure or the form. But when closely regarded, it is seen that these two points differ only in degree.

Â§ 4. As regards texture, the component parts may be reduced to others more simple, which in their turn differ from each other, in their degree of simplicity, and may, therefore, be divided into proximate and remote.

Â§ 5. The remote constituent parts of the organic form, are finally reduced to two, of which one appears constantly under a given form, which is not the case with the other, although this is equally susceptible of figure. These parts are the globules and a coagulated or coagulable substance. The part is solid or liqiiid, according as the latter, in the first or second state, exists alone, or with globules, and it has an external form in the former case. All the solid and fluid parts do not contain these last two constituent materials : but the globules never exist alone ; they are always imbedded in a coagulated or coagulable substance.

Â§ 6. The term globule is not well adapted to corpuscles having a definite form ; for it is proved that many of them, particularly the globules of the blood^{1) are not equally thick in all directions, but are flat and lenticular, since, if rolled on an oblique surface, their edges maybe seen with a microscope. (2) They are however never angular, but always rounded, and vary in form, size, number, color, and chemical composition, not only in different subjects and in different parts of the same subject, but even at different stages of life, w'hether they pass or return, and are regular or irregular.

Thus, in regard to form, the globules appear more complicated in some parts than in others. In the blood, according to the best authorities, they are formed of a central part, which is solid, and of an external part, which is hollow, vesicular, and incloses the first, but does not adhere to it. Every where else their structure appears more simple, for one only of these two parts is perceived ; but whatever may be the region of the body in which they are examined, their general form appears the same in the same animal, that is, they are never found oblong in one part, and rounded in another. In man they are rounded.

The globules differ much in volume in the different parts of the body : they are smaller in the liver than in the kidneys, and larger in the spleen than in the liver. (3) Those of the nervous system are smaller than those of the blood; (4) these latterare in their turn larger than those of the lymph, of milk, and of chyle. (5) At the commencement of suppuration(6) they are smaller than when it has existed for some time. (7)

(1) C. H. Schultz has very recently attempted to demonstrate that blood endowed with the vital principle is not composed of globules swimming in serum, but forms a homogeneous mass, which is divided into numerous corpuscles, exercising, upon each other and on the parietes of the blood-vessels, the most lively action ; so that they are reciprocally drawn together, or rather are united, and then reform themselves anew : they attract each other mutually, and join to form one mass : this mass resolves itself into several parts ; and the same thing occurs again. This new theory of the vitality of the blood founded on microscopic observations, if confirmed, will have a powerful influence on physiology, and will serve to explain the existence of animal scions, which have been rejected'too soon, because we could not understand them. See two important memoirs of Schultz in the Journal Complementaire : Observations microscopiques sur la circulation du suc propre dans la chÃªlidoine et dans plusieurs autres plantes, vol. xvi. p. 208. and vol. xvii. p. 136. MÃ©moire sur les phÃ©nomÃ¨nes de la vie dans le sang, dÃ©montrÃ©s par les observations microscopiques, vol. xix. pp. 19 and 212. The observations of this physician have been resumed by Dutrochet, who thinks they were founded on an optical delusion. â€” Same Journal, vol. ix. p. 289. This subject demands more attention, and we invite to it the talent and zeal of physiologists. We ought, however, to add that Doellinger {Was ist Absonderung und wie geschieht sie, Wurtzburg, 1819, p. 21.) had already rejected the theory of globules swimming in serum ; but he admits the existence of globules : he thinks too that the blood should not be termed a fluid ; for it does not run like water, but like the fine sand contained in an hour-glass. F. T.

(2) Hewson, Experimental Inquiries, London, 1777, vol. iii. p. 15. LeuwenhÅ“ck says they are globular in man and the mammalia, but flat in fishes. â€” (Arc. Nat. vol. i. p. 51.) Schmidt states they are round in man and the mammalia, and elliptically oblong in all other animals. â€” (^Sur les globules du sang, in the Journal Compl. du Diet, des Sciences Med. vol. xviii. pp. 107 and 210.) See also the work of G. A. Magni, (Nuove osservazioni microscopiche sopra le molecule rosse del sangue, Milan, 1776,) as likewise that of PrÃ©vost and Dumas, (in the BibliothÃ¨que Universelle, 1821, July, August.)

(3) Wenzel. Prodromus eines Werks Ã¼ber das Gehern des Menschen und der SÅ“ugthiere, Tubingen, 1806, chap. iv.

(4) Prochaska. De Struct. Nerv. Vienna, 1779, chap. iv.

(5) Hewson. Exp. Inq. tabs. 1 and 4.

(6) Home. On the Properties of Pus, London, 1778, p. 14.

(7) M. Edwards, from his microscopic researches upon the cellular, fibrous, and vascular tissues, the muscles, and the nervous tissue, or pulpy substance of the brain

Some fluids, as urine, contain very few globules ; the same is true of some solids, as the mucous tissue, the fibrous parts, the cartilages, the bones. On the contrary, there are more in the blood, the muscles, and the nervous substance. More are found in the blood than in chyle and milk ; they are also more numerous in perfect pus than in that which is just forming.

The color and chemical composition of the globules are determined usually by those of the parts ; since the latter are constituted by them, and they cause the diffÃ©rences of the parts. This proposition appears incontestible, at least as regards the solids.

In all these respects the globules are subject to periodical changes. The analogy between man and animals renders it probable that at different periods of life they vary considerably also in him, both as regards form and volume ; for in the fetuses of birds and reptiles, globules of blood have been found of another form and much larger than in the adults. The same remark is true in respect to color and chemical composition ; since the two qualities do not remain the same in the same parts at all periods of existence. Their number certainly changes regularly at different times. At the commencement of the first period, when the fetus is forming, no globules can be perceived, and the substance of the new being is composed entirely of a coagulable, homogeneous liquid ; this soon separates into a fluid part and another which is more consistent ; the latter is surrounded by the former, and, as a plate of zink moistened with water, is alternately in a positive or negative state of electricity, according to its situation, so the positive state every where prevails in the solid portions, or the globules, and the negative, in the liquid which surrounds them. But when the fluid, which was at first homogeneous, once divides into globules and a liquid, the globules continue for some time more apparent than they are afterwards, and then may be discerned in all parts of the fetus.

Â§ 7. These two remote constituent parts, the globules and the coagulable liquid, produce, either the second alone, or both combined, two principal forms : in the first, the length much exceeds the other dimensions ; in the second, it is more nearly equal to the breadth, although they both exceed the thickness. The first form is called fibrous, the second, the laminar : the fibrous form belongs usually only to the coagulated liquid, which is sometimes changed into fibres, even without the globides, as in the bones, tendons, and nerves, has determined that the elementary parts of these tissues are formed and arranged in the same manner in every animal observed by him. Edwards thinks he can establish, as a general law, that the proper elementary structure of these different tissues is the same in all animals. A still more remarkable fact is developed by his researches, viz., that the form and size of the globules are always the same, whatever is the organ or animal in which they are examined. We must then believe that the primitive form of the molecules of solid and organized animal matters is always constant and definite. In fact, as Edwards states, the organic tissues above indicated are formed of spherical corpuscles â€¢j-.l.j. of a millimetre in diameter, whatever may be the other properties of these parts and the functions for which they are designed. â€” (H. M. Edwards. MÃ©moire sur la structure Ã©lcmeniaire des principaux tissus organiques de l'homme, Paris, 1823.) F. T.*

M. Haspail concludes, from some recent microscopic observations, that the membranes, when isolated, and reduced to their proper consistence, are not composed of globules perceptible by our means of observation, and however coarse those examined may be, their surfaces appear smooth, and not granulated. â€” Am. Med. Jour. Nov. 1828, from the Repertoire d' Anatomic.

The globules tend very much, with the coagidable liquid, to form fibres ; that is to say, to arrange themselves one after another, as is seen in the nervous and muscular systems ; although in several parts, as in the substance of the viscera, they are deposed without any regularity, being placed indiscriminately in the coagulable fluid. The latter is, however, inseparable from the globules, for it envelopes them entirely ; even the most delicate fibres are surrounded with a sheath, produced by this fluid, in which all the parts are, in some measure, placed, and in the hquid portions of which, the globides contained in the flidds float.

The properties of the fibres vary as much as those of the substances which constitute them. There is, then, no single or elementary fibre.

Â§ 8. The union of fibres and laminÃ¦, or of the latter alone, produces spaces of ditferent forms, called cellules. Gallini, Ackermaim, and some others, were wrong in consideiing these cells as the only final elements of form. The very expressions of these authors refute their own opinions ; for if â€œ all the parts of the body are aggregations of laminÃ¦ of different sizes, joined one to another at different angles, so as to intercept between them, spaces or cells of various sizes,â€(l) or if â€œfour mucous laminÃ¦ joined at an acute angle, enclosing a space called a cell, are the homogeneous elements of every organization,â€ (2) it is easy to perceive, that the cellular formation comes manifestly from the lamellar, and thus that the cells are a secondary formation. To this ii may be objected that the globules are, properly speaking, cells, and hence that the fibres themselves are composed of cells ; but this opinion cannot be admitted, because these globules exist in a loose state in the fluids. Besides, there are many parts in which there are no traces of these hypothetical cellules, and which appear to be produced by a homogeneous fluid coagulated in large laminÃ¦, as is seen particularly in the serous membranes. It is equally improper to call the fibres the crystaline forms of organized bodies. (3)

Â§ 9. In the body the fibrous formation exceeds the lamellar very much, and the parts themselves in the whole form in which the dimensions of length and breadth are equally developed, such as the fibrous membranes, the broad bones and muscles, manifestly exhibit the fibrous texture internally, a chcumstance belonging, unquestionably, to the law, in vhtue of which the dimension of length, in the whole body, exceeds the other two. The fibres are easily distinguished in the nerves, muscles, most of the bones, and the fibrous organs. A tissue, at once fibrous and lamellar, is found in the viscera, and partially, also, in the bones.

Â§ 10. These elements, disposed in fibres and laminÃ¦, winch originall}'^ differ much in figureand composition, produce, when united, several proximate or immediate constituent parts of Ihe fio7-m,\vhich. vary considerably, both in their internal and external figure. These bodies have received the name of systems, in relation to iheix form, bywhich we understand, that the different parts of a given combination resemble each other, and differ from the others in all the parts of the body. Many, as the mucous, nervous, and vascular systems, deserve this term in a still more special manner, because they form an uninterrupted whole. Here the connection is less intimate in some systems than in others ; for example, the bones and muscles do not offer, like the above mentioned, an uninterrupted continuity in their proper substance ; nevertheless, they are so united into a whole by peculiar systems, to wit the fibrous, that the periosteum which covers the bones, not only has the same structure as the accessory ligaments which pass from one bone to another, and as the tendons of the muscles which are inserted into it, but also forms with them a continuous whole.

(1) N. Gallini, Betrachtungen Ã¼eber die neuen Fortschritte en der Kenniniss des Menschlichen KÅ“rpers, Berlin, 1794, p. 61.

(2) Ackermann, Darstellung der Lehre von den Lebenskrceften, vol. i. p. 11.

(3) Antenrcith, Physiologie, vol. i. p. 7.

Other parts of the body, on the contrarjt, as the viscera, and serous membranes, are isolated, and are retained, one to the other, only by the first three systems, which are universally diffused, and form an uninterrupted whole.

The different parts of the body receive also the name of tissues, {textus,) in regard to their internal structure ; and that of organs, by reason of the actions they execute ; for each acts, in its manner, for the preservation of the body, which is itself called an organism, in reference to the activity of the parts constituting it.

Â§11. These different parts vary much from each other, in their external and internal form, their chemical composition, their mode of vital activity, and their functions. They differ most, however, in the degree of complication. There are, in this point of view, two grand principal classes, which may be called, the first, the class of simple organic organs or systems, or of similar parts, {partes similares,) because they are found in the body more than once ; the second, the class of compound organs or systems, or of dissimilar parts, {partes dissimilares,) or as Bichat terms them, of apparatus, because they are found in the body only once, or at most twice. The union of the simple organs takes place in a determined manner, many of them uniting to give rise to parts designed to accomplish a special function, single, or at most double. Combining thi.is, they form the apparatus ; so that the body, considered as a whole, results from an assemblage of compound systems which we must decompose and reduce to their elements, if we wish to have an exact and complete idea of the conditions of their existence. The hand, the foot, each viscus, the different organs of the senses, &c. are examples of these apparatus. Nevertheless, v/e should observe, that the line of demarkation between the simple and compound organs is not rigorously traced. The simple organs themselves are composed of several different parts, and combine and unite differently. As for the more complicated organs, we can, with attention, refer them to simple systems, since we finally find, in several, the same conditions which are presented by the latter. This is the case, at least with many of them, and particularly with those termed uiscera ; doubtless all these do not differ from other parts, sufficiently to constitute special organs ; but when examined attentively, we ascertain, first, that they are only simple modifications, or branches of one and the same system, the cutaneous ; and secondly, that they are so analogous to the vascular system, that no perfectly distinctive characters can be assigned to them; both are canals having their parietes formed essentially of two layers, an internal and an external, of which the latter tends to move the contents, and which are both formed with vessels and nerves. We are then embarrased in attempting to decide on the subject of certain parts, whether they should be regarded as simple or compound organs. The skin, for instance, is certainly an apparatus, a compound organ, if we consider it in its totahty, as is necessary to acquire an exact idea of its functions : but, we can distinguish in it several particular systems, since we can reduce it mechanically, not only to parts which are found in other organs, but into those which are peculiar to it, as the cutis, papillary tissue, epidermis, han, and nails.

Â§12. We ought not, however, to think, from what has been said, that a classification founded on the difference of tissue and of composition, is useless and impossible ; on the contrary, it appears more proper, not only to examine the simple and compound organs separately, but farther, in making the table of the most simple systems, to consider all the parts manifestly connected with a compound organ, as belonging to this organ, and to describe them with the others, rather than follow the opposite course, and to refer the history of these different parts to that of the simple systems to which they belong. This method is decidedly J^^best, at least for those systems which do not form an entire wholejÂ« me vascular and the nervous systems.

Â§13. The number of systems should be determined after a profound study of the properties possessed by the different parts ; since we must admit as many particular systems as we can demonstrate different tissues. But at the same time we must be careful to refer to the same system, all the parts which resemble each other in these different points of view, however great may be the distance between them.

Â§14. To approach the truth as nearly as possible in this respect, we must clearly distinguish the final forms and the final tissues, to which all the formations are reduced, that is, the laminÃ¦ and the fibres, from the forms which proceed fi'om a particular aiTangement of the latter, and which appear to constitute so many distinct species, because each of them has less analogy \vith all the others than exists between those of their parts, which are found hi different regions of the body. Sufficient attention is not generally paid to this difference ; hence why the forms of the second species have been united with those of the first.

Haller(l) and some other physiologists admit only three tissues, to which all the others are refen'ed ; these are the muscular fibre, the â€¢ nervous fibre, and the mucous tissue. They assert that all the organs which are not formed from the first or second of these fibres, belong to the third division.

This resembles the diifision of those authors who admit three primitive forms: 1, the cellular, or membranous; 2, the vascular, or Jibrovs ; and 3, the nervons.{\) These two classifications have the same defect, for if, in arranging the first elements, only the ditÃ¯erence of texture is considered, the number of divisions is too great, since the nerr-ous and vascular formations belong evidently to the same class, that of the fibrous organs. But if we attend to the specific differences of tire external and internal form, and of the actions, these two classifications are insufficient, because the number of the forms and of the modifications of the vital phenomena is much greater.

(1) De part. corp. hum. vol. i. p. 46.

The classification of Dumas(2) is more correct; he admits four tissues ; the cellular, or spongy ; the muscular, oi fibrous ; the mixt, or pa renchymalous ; and the lamellar, or osseous. The first three represent truly the primitive form, although the term muscular, given to the second, is badly chosen ; but the fourth should be rejected, as the osseous tissue evidently belongs to the second class.

Â§15. Nevertheless, as these classifications announce only the primitive forms, and consequently may be referred to what has Ijeen Stated above, (Â§7,) they are far from removing the differences pointed out between the particular systems. It is less correct also to derive certain systems from others, and hence to regard them as modifications, than to say, certain systems are extended more generally than others, and contribute to their composition and preservation, tvhile they do not exercise a similar influence upon them.

With these ideas, Bichat has formed his general anatomy, although his classification is not perfectly correct. He admits general systems, andparticular systems; the first, which are also called gejie?'ariâ€˜re, because they are generally distributed, and concur to form all the others, are six in number: the cellular, ox mucous, the arterial, the venous, the exhalent, die absorbent, and the nervous systems.{3) He has even increased this number by one, having subdivided the nervous system into the nervous system of animal, and that of organic life. If we unite, as should be done, the second, third, fourth, and fifth, we reduce the systems to three, the mucous tissue, the vascidar system, and the nervous system, which, adopting Bichat's meaning, might be called primitive, or general systems, but to which this name is not applicable when we confine ourselves to the acceptation universally received.

Besides these three, we usually establish but a small number of systems, because the general characters of the tissues, in different parts of the body, are neglected, while other tissues, which are composed of very different elements, are considered as primitive ; and, in tracing their history, we describe the different parts which concur to form them, but without reflecting that several of these parts, although they do not form a connected and coherent whole, and often differ, even in their external form, do not the less belong to one and the same system, when their most essential properties are considered. Thus a muscle is described as composed of a fleshy and of a fibrous portion, without thinking that the first alone enters into our idea of what a muscle should be, and that, the second belongs not to the muscle only, but also to other and very difierent parts.

(l) Walther, Physiol, vol. i. p. 97.

(2) Prop, de phys. vol. ii. p. 4.

(3) Bichat's General Anatomy, trans. by G. Hayward, vol. i. p. 79.

Other systems are then referred to the hones^ cariilages, ligaments, muscles, and viscera. Hence anatomy osteology, to

which is joined chondrology, as most of the fiynirfrnt- are blended with the bones, sytulesmology, myology, splanchnology, angiology, and neurology. Nevertheless, this division does not exhaust, by any means, the subject of anatomy. The bones, cartilages, ligaments, muscles, and viscera, are, it is true, essentially dilFerent organs : but, first, the class of hgi^ments is faulty for two reasons : because it comprehends two kinds of different tissues, on the insufficient ground merely that both extend from one bone to another ; secondly, because there are several organs, which deserve, as much as the ligaments, to be admitted to that class, even after rectifying it, as it might be amended. Again, the class of viscera, which may safely be called a negative class, embraces organs so dissimilar, that no general characters can be assigned it ; and 'w.e know not how to retain it, at least, as we do not wish to give it the name of the class of the most complicated organs or apparatus.

Â§ 16. Here we cannot overlook the services which Bichat has rendered to anatomy, regarded philosophically, and as a science, although we must admit he has made too many classes.(l) He mentions fourteen besides the generative systems, (Â§ 15,) viz ; 1, the osseous system : 2, the medullary system : 3, the cartilaginous system : 4, the fibrous system :

5, the fibro-cartilaginous system : 6, the muscular system ofi animal life : 7, the muscidar system of organic life : 8, the mucous system : 9, the serous system: 10, the synovial system : \\, the glandidar system : 12, the cutaneous system : 13, the epidermoid s7jstem,and 14, the pilous system. (2)

Among these systems, we suppress the medullary system, which is the same as the cellular tissue, and the sjmovial system, a slight modification of the serous system ; the two muscular systems should be

(1) Bichat gen. anat., Vol. ii. p. 141.

(2) It may be well to mention how modern physiologists and anatomists have divided the organic tissues since Bichat.

Walther thinks that all the tissues are derived from'the cellular; and thÃ¢tthey proceed from this primitive tissue in two series : one comprising the serous and synovial membranes, the mucous membranes waÃ glandular tissue, the dermis, epidermis, the horny sluA pilous tissues: the other, the muscular tissue, tlie fibrous membranes, the fibro-cartilages, the cartilaginous, and osseous tissues. â€” [Darstellung des Bichafscliens systems : in Schelliiig and Marcus, Jah.rbv.chen der Medicin.) Vol. ii. P. i. p. 49.

Dupuytreyn has diminished the number of tissues admitted by Bichat, and has added one very important, wMch Bichat had omitted : 1, the cellular system : 2, the vascular system, arterial, fcnous,and lymphatic : 3, the nervous system,cerebral,aiiA ganglionic : 4, the osseous system: 5, the proper fibrous system, fibro-cartilaginous, and dermoid :

6, the muscular system, voluntary and involuntary: 7, the erectile system: 8, the mucous system : 9, the serous system : 10, the horny system, pilous, and epidermoid : 11, the parenchymatous system, properly so called, and the glandidar.

Chaussier divides the partsofthe animal body as follows: 1, the bones: 2, the articular cartilages, of prolongation, of ossification : 3, the muscles : 4, the ligaments : 5, the vessels: 6, the nerves: 7, the vascular ganglions, glandiform bodies : 8, the simple follicles, or crypts, proximate,compound : 9, the lachrimal,salivary,and mammary glands, thepancreas,liver, kidneys, and testicles: 10, the lamellar, muscular, albugineous, simple villous, or serous, compound villous, or follicular, and coriaceous membranes, and epidermis: II, the lamellar or cellular : 12, the viscera, the digesiire respiratory, circulatory, urinary, and genital organs, and those of the senses . â€” ( Table synoptiques des solides organiques.)

united. .We ought not to separate the fibrous S3^stem fi'om the epidermoid s\'stem, which, perhaps, should be joined to the dermoid system. .Finally, all the probabihties authorize us to unite the dermoid,

It. Cloquet admits fifteen tissues, viz: cellular tissue, membranes, vessels, hones, cariitages, ÃŸbro-cartilages, ligaments, musetes, tendons, aponeuroses, nerves, glands, follicles, lymphatic ganglions, and viscera. â€” {Cloquet's Anatomy, Boston, 1830.)

Lenhossek numbers only eig-bt tissues : 1, the cetlular tissue ; 2, the mucous, serous, fbrous, und mÃ¼ed membranes; 3, the cuta;icous system, including ihe epidermis, nails, and hair ; 4, the vascular, arterial, venous, capillary, and lymphatic system; 5, the nervous system ; 6, the muscular system ; 7, the glandular system ; 8, the osseous system, witli the cartilages and the medulla. â€” (Physiologia meÃ¢icinalis.)

Mayer also admits eight : 1, the lamellar, or albugineous tissue, tissue of the crystatine and cornen, epidermis, hair, and nails; 2, the cellulo-flbrous, cellular, adipose, medullary, serous,synovial tissues, and that of the vascular membranes,dermoid system, system of the mucous network, tissue of the uterus ; 3, the fibrous tissue, proper membranes of the glands, of the spleen and kidneys; albugineous membrane of the testicles, tissue of the corpora cavernosa, tissue of the sclerotica, of the dura-mater, and of the periosteum, the perichondrium, fibrous articular capsules, ligaments, aponeuroses, tendons, ncurilema ; 4, the cartilaginous tissue of organic life, or fibro-cartilage, that of animat life, or articular cartilage; 5, the osseous tissue ; 6, the glandxUar tissue; 1, the muscular tissue, and, '8, the nervous tissue. â€” {ÃJ eher Histologie und eine neue Einthcilung der Gewebe des menschlichen KÅ“rpers, Bonn, 1819.)

Kudolphi divides the solid parts into simple and compound. 'Fire simple parts are :

1, the cellular tissue ; 2, the horny tissue, which comprises the epidermis, epithelium, nails, and hair : 3, the cartilaginous tissue ; 4, the osseous tissue ; 5, the tendinous fibre; 6, the vascular fibre ; 7, the muscular fibre; 8, the nervous fibre. The compound parts are : 1, the vessels, both general and special ; the former comprising the arteries, veins, and absorbents, and the latter, the special canals of the excretory organs, as the biliary, salivary, urinary, and seminal ducts : 2, the membranes, which are also divided into general, as the serous, mucous, and fibrous, the dermis and epidermis; and special, as the membranes of the ovum, of the eye, and encephalon : 3, the viscera ; 4, the glands. â€” {Grundriss der P/i.yswlogte, Berlin, 1821.) See alsoC. A. Budolphi, Programma de corporis humanÃ®partibus similar ibus, Grispwald, 1809; and S. J. Bugaiski, DissertÃ¢t io de partium corporis humani solidarum similarum aherrationibus, Berlin, 1813.

J. Cloquet classes the tissues of the human body as follows: 1, the cellular system :

2, the adipose system ; 3, the vascular system ; 4, the nervous system ; 5, the serous system ; 6, the mucous system ; 7, the ligamentous system : 8, the elastic system ; S, the cartilaginous system ; 10, the fibro-cartilaginous system ; 11, the osseous system; 12, the muscular system : 13, the erectile, or cavernous system; 14, the gfandular system ; 15, the horny system. â€” {Anatomie de l'homme, ou Description etfigures lithograph iÃ©es de toutes les parties du corps humain, Paris, 1821.)

lleusinger refers ail the organic tissues to eleven : the formative, or cellular, the horny, the cartilaginous, the osseous, the fibrous, the membranous, the nervous, the serous, the vascular, the parenchymatous; and the glandular. â€” {System der Histologie, Ki.senach, 1822.)

Ducrotay dc Jllainville admits a generative clement, the cellular, or absorbent tissue, and two secondary elements, the muscular, or contractile fibre, and the nervous, or exciting fibre. By slight inodifications, the cellular tissue produces nine systems : the dermoid, mucous, fibrous, fihro-cartilagirwus, and cartilaginous, osseous, serous, synovial, arterial, venous, and lymphatic. The first secondarj^ element produces three systems, the subdermoid muscular, submucous muscular, and the profound, muscular ; and the second secondary element forms four : the pulpous ganglionic, the apulpous ganglionic, the nervous system of animal life, and the nervous system of organic life. â€” {Principes d' Anatomie comparÃ©e, Paris, 1822.)

Bedard admits 11 classes of tissues: 1, the cellular and adipose tissue ; 2, the serous membranes; 3, the tcgumcnlary membranes; 4, the vascular system ; 5, the glands ; (i, the ligamentous tissue ; 7, the cartilages ; 8, the osseous system ; 9, the muscutar system. ; 10, the nervous system ; 11, the accidental formations. â€” {Siemens d'anatomie gÃ©nÃ©rale, Paris, 1823.)

We may also consult, in regard to similar parts, or simple tissues of the animal economy, Fallopia, De partibus simitaribus humani corporis,'Nuretxthurg, 1575 . â€” Malacarne, i sislcmi e la loro reci]>roca infiuenza indagati, Padua, 1803.â€” Prochaska, Tiemerkungen Ã¼ber den Organismus des menschlichen KÅ“rpers, Vienna, 1810. â€” â– Mascagni, Prodrumo della grande Anatovna, Florence, 1819 : Milan, 1821, 4 vols.

rsesss^^i and glandular systems. Thus the twenty-one systems admitted by Bichat, are reduced to twelve, and even to ten, viz ; the mucous, vascular, nervous, osseous, cartilaginous, fibrous, fibro-cartilaginous, muscular, serous, and dermoid systems.(l)

These will be examined in the general anatomy, according to their general conditions, and in the special anatomy, topographically, or according to their local relations ; when the general considerations of the organic form, including the human form, shall have been first given.

Â§17. The general laws of the organic form, and hence those which belong to man, are as follows : first, the outline is not sharp and angular, but rounded. This law is true, both in regard to the form of the whole body, as well as to that of each of its organs, and its smallest elements. The roundness of the form usually depends upon the fact, that all the solids are accompanied with fluids, for the first effect of solution is to smooth down the angles of solid bodies. We mention, as examples, the round form of the cavities of the body, of the viscera, vessels, nerves, muscles, bones, &c.

Â§18. II. The dimension of length exceeds the others. This law, already mentioned above, (Â§9,) is seen no less in the body as a whole, and in the external form, than in the internal form, or the texture of its parts. The whole length of the body, much exceeds its breadth and thickness. It is divided into three principal regions, the head, trunk, ar\d the limbs, or extremities. Of these, the head alone is round, but it is only the upper and bulging extremity of the vertebral column, that is of the osseous base of the trunk, in which the dimension of length evidently predominates. This column is enveloped by lateral expansions, producing cavities designed to lodge the apparatus placed before them, but it is not entirely concealed. The excess of length is most manifest in the extremities, generally, and in their different parts. It is the same with all the particular systems. The dimension of length much exceeds the other two in ohe vascular and nervous systems. It is especially marked in the hair. The luunber of the long bones, muscles, and fibrous organs, is much greater than of those which are broad or thick. The intestinal canal, the trachÅ“a, ureters, urethra, &c., are very narrow in proportion to then length.

This rule applies exactly to the texture, since the fibrous is the most common of all, and every large fibre is divided mto an endless multitude of others which gradually become smaller and smaller.

Â§19. III. The structure of the organism is radiated. From the central parts, which are largest, originate others, which are smaller, which move in all dh'Sns, and in which the dimension of length especially predominates. Thus the extremities arise from the trunk : the long, and naiTow ribs, from the spine ; the nerves, from the brain, spinal marrow, and ganglions, the vessels from the heart. But, besides thesegrand centres, from which the rays commence, there is an infinite number of the second order, since each ray usually divides into several, which, in some systems, particularly the general, as that of the nerves and vessels, also, in llieir turn subdivide. The rays then ramify.

(p Perhaps it would be better to suppress, not only the fibro-cartilag-inous system, which is a mixed, or compound tissue, as its name indicates, but also the serous system, which has the same relations with the mucous, or cellular tissue, as exists between the dermoid and epidermoid, which Meckel has very properly united. F. T.

Another general law is, that the number of rays augments as they depart from the principal centre of radiation, and their volume diminishes in the same jiroportion. Thus, instead of one long bone, as in the arm and thigh, we find two, which are smaller, in the forearm and leg, twenty-six in the foot and twenty-seven in the hand, still smaller. The number of the muscles and tendons inserted into the bones, and of the ligaments, multiplies in the same manner, and they diminish in size in the same ratio. In the whole course of the nervous and vascular trunks, branches and tvings are constantly sent off in every direction, at different angles, and at certain distances from the principal trunks they divide into others still smaller, which are themselves again subdivided.

I'his (hvision is true, not only in respect to length, and from without, inward : it also occurs in the thickness of the oigans ; for the muscles and nerves represent bundles composed of cords, which are, in their turn, formed of fibres and filaments.

Â§ 20. IV. At the side of this law of ramification proceeds another, the law of anastomosis. These rays, it is true, subdivide a great many times, but the subordinate rays which result froni this division, unite in different ways with each other, and with the principal ray. The same remark is true in regard to the continuity, that is, to the thickness of the organs ; for these anastomoses take place from above, downwards, and also from within, outwards. The different trunks, branches, and twigs of the nerves and vessels, the different tendons of the same muscle, the simple fibres, their fasciculi, both large and small, in the nerves, or at least in many muscles, the fibres of the bones, and those of the fibrous organs, mutually anastomose together. We can, to a certain extent, mention here those bones placed side by side, which, in addition to the ligaments necessary tc keep them in place, are connected by interosseous membranes.

Â§ 21 . V. These rays arc not straight, hut nsually more or less curved. This law, which has been termed the km of the spired line, is seen in the vertebral column, which describes several curves ; it is confirmed also by most of the long bones. The cochlea, semichcular canals, several vessels, excretory ducts, and nerves, are also examples. Finally, this is sometimes seen very evidently in the double monsters : since, when two heads arc placed side by side, or two bodies are united by a head, the direction of these two bodies or two heads is always different ; so that the monster, considered as a whole, appears spiral.

Â§ 22. VI. The difi'erent organs are someichat ancdogous.{\) It has aheady been stated (Â§5) that the texture of the most dissimilar organs can be reduced to two elements of form, which are generally united ; we have there indicated the analogy which exists between the final structure of the organs, and to which many writers have wrongly given still more extent. As the structure of almost all the organs is radiated, (Â§19,) it follows that the analogy of their external form is demon (1) See our Memoir on the analogy of organic Jorms, in our Beylrcegc zur vergleichenden Anatomie, vol. Ã¼. p. 2.

strated. It exists even where there is no manifest radiation ; since we there remark parts first dilated, and others which are contracted. Thus, the brain is joined to the spinal marrow, the vertebral column to the skull, the vascular trunks to the heart, the esophagus to the buccal cavity, the intestinal canal to the stomach, the trachea to the larynx, the cystic duct to the gall-bladder, the ureter to the pelvis of the kidney, and the urethra to the bladder.

Another great analogy between the different systems is established by the circumstance that those which vary the most from each other are formed after the same type in the same parts of the body. Thus, the simple trunk of the arteries of the superior or inferior extremities is almost always divided into two different branches, at the place where the number of bones is doubled ; in general, the divisions and unions coiTespond exactly in the different systems situated near each other. The number of the arteries destined for the fingers and toes is the same as that of these appendages. The nervous trunks and the vessels anastomose in the palms of the hands and soles of the feet. In the same manner, the tendons of the flexor and extensor muscles of the fingers and toes are united by mucous and tendinous slips. The different parts of the nervous system and of the vascular system proceed together.

The whole form of the body is repeated not only in those systems which are generally diffused in the entire economy, and which form a whole more or less contmuous â€” as the cellular tissue and the nervous, vascular, osseous, and muscular systems â€” but also in each of the organs. We should refer to this the form already pointed out as belonging to so many systems, the peculiarity of which is an enlargement at one extremity and a continuation into a narrower process at the other. We must refer to this also the manner in which most of the organs, and principally the glands, receive their vessels. In fact, we always observe a considerable depression, a fissure, about the centre of these organs, through which the vessels enter and emerge exactly as in the fetus. Here the organ is open to a certain extent, and is much more so the nearer it is to its formation, exactly as in the fetus, which at first is open entirely before.

The peculiar analogy of certain systems is still greater. This is seen particularly in the genital organs and the intestinal canal.(l)

Â§ 23. VII. The body is formed symmetrically. We find an analogy, and even a resemblance to a certain extent, not only between the different organs, but particularly also between their different regions. (2) This analogy may be demonstrated, both in the breadth, and in the length, and thickness, or even between its right and left sides, (3) between its upper and lower extremities,(4) and between its anterior and postenor faces.(l) We must here remark generally, that the sijnilitude is never perfect^ and that usually one extremity predominates, more or less, over the other. This is sometimes expressed by the greater volume, and sometimes by the greater development in the radiation of corresponding parts. Nor is the symmetry equally great in all directions, nor between the different corresponding regions. The most perfect is the lateral symmetry, or that of the two sides of the body ; and the most imperfect, that of its anterior and posterior faces. The nervous, osseous, ligamentous, and muscular systems, and the genital apparatus, are the most symmetrical parts ; we find less symmetry in the vascular system and in the thoracic and pelvic viscera, if we except the genital apparatus.

(1) A. A. Meckel. De genitalium et intestinorum analogia, Halle, 1810. Trans, in J. F. Meckel's Beytr. zur vergl. Anat. vol. ii. p. 2. No. 1.

(2) J. F. Meckel, loc. cit. p. 95.

(3) Du Pui, De liomine dextro et sinistra, Leyden, 1790. â€” Heiland, Darstellung der VerhÅ“ltnissen zwischen der rechten und linken HÃ¦lfte des menschlichen Koerpers, Nuremberg-, 1807. â€” Loschge, De sceleto hominis symmetrica. â€” Erlangen, 1795. â€” â– f^'^onte^gia, Fasciculi pathologici, Turin, 1793 : morbi symmetrici et asymmetrici. â€” Mehlis, De morbis hominis dextri et sinistri, Goettingen, 1818.

(4) Vicq-D'Azyr, Sur les rapports qui se trouvent entre les usages, et la structure

Â§ 24. 1. The most perfect lateral sijmmetnj is in the external form, and on the surface of the body. Hence, it is better known there. In fact, the body seems to be composed of a right and a left half, since most of the organs are double, and those which are single, are placed more or less on the median line, so that a plane drawn from before backward, would divide them into two nearly equal parts, as they are formed of two lobes united and blended on the median line. These latter, when placed betvmen cavities, form septa ; and on the contrary, are called media of communication, commissures, when placed between two corresponding parts, which are otherwise separated.

Similar arrangements are found in all the systems, and we may say with justice that a commissure exists more or less perceptibly in all the body, althoitgh it is often interrupted ; this, at the same time, forms a septum between the right and left sides. (2) Thus, the falx cerebri descends from before backward, from the centre of the skull ; and the internal ridges of the frontal and occipital bones correspond to it. Below it, is the corpus callosum which unites the two hemispheres of the cerebrum ; below, is the septum lucidum, formed of two layers closely applied to each other, and which represent in the brain what the falx and spinous ridges have in the skull. The nasal cavity is divided into two parts by a partition, which is bony above and behind, and cartilaginous before ; the former of these portions being formed by a part of the os ethmoides, and by a particular bone, the vomer. The frena of the lips in front, and the uvuia behind, represent this septum in the mouth. In the chest, the internal parietes of the pleurae, which partly touch, and are partly separated by organs placed between them, form the anterior and posterior mediastina, and thus establish a line of demarkation between the two halves of the thoracic cavity. A longitudinal septum, generally perfect, exists between the right and left sides of the heart. This septum is only indicated in the abdomen, where the two halves seem blended together ; the division has been destroyed, or its formation has been prevented, by the considerable mass of organs which are inclosed by this cavity. We trace it, hoAvever, forward and above, in the suspensory ligament of the liver Avhich extends from the inferior face of this gland to the umbilicus, and below, in the analogous but less extensive fold of the peritonoeum, which reaches from the bladder to the umbilicus, covering the remains of the obliterated umbilical artery and urachus ; and finally, behind, in the other fold of the peritonÅ“um, which goes from the anterior face of the lumbar vertebrae to the intestinal canal, and which is called the mesentery. On the median line of the penis in the male, and of the clitoris in the female, we find a perpendicular septum. The corpus spongiosum of the penis, and the septum and the raphe of the scrotum in the male, are situated exactly on the median line. The cellular tissue, which unites the skin to the subjacent parts, is thicker in all regions of the body on the anterior and superior, than on the posterior face. The vessels frequently anastomose together on the median line, as is seen in the coronary arteries of the lips, the sinuses of the medulla spinalis, and the cerebral arteries, which, supplying the Uvo hemisphei'es of the brain, unite by numerous transt'erse branches. So, likewise, the trvo vertebral arteries unite on the median fine, to produce the basilaiy, and the anterior and posterior spinal arteries descend along the spinal marrow. Several smuses of the dura mater exist on the mediair line of the skull. The aorta, venÃ¦ cavÃ¦, thoracic canal, the azr^gos vein, and partly even the esoi3hagus, describe a curve, Avhich corresponds very nearly to the median line of the thoracic and abdominal cavities.

des quatre extrcmitcs danr "omme ct dans les quadrupÃ¨des; in Mem. de Paris, 1774, vol. ii. â€” Ã¼lcckel, loc. cit., p. 97â€” 148.â€” Falguerolles, De e.Tlremitalum analogiÃ¤, Erlanfrcn, 1780.

(1) Meckel, loc. cit., p. 148.

(2) R L. H. Ardicu, Considcralions sur la ligne mÃ©diane, Sira.Ã¤hurg, 1812.

The vertebral column, sternum, occiput, os frontis, os ethmoides, and os sphenoides, are those parts Avhich are unmated and distinct, and serve to join the corresponding parts of the same system, as they are united with them, and wedged in by them. Those bones Avhich meet on the median line, but remain always distinct, although united by an intermediate substance, as the ossa parietalia and ossa ilia, form the connecting link between them and those which do not touch in the least.

The brain and spinal marrow, the heart, womb, vagina, prostate gland, bladder, urethra, thyroid, and thjmious glands, the intestinal canal, the trachea, larynx, and tongue, are unmated, but are formed of two similar portions, between which the median line passes, at least to a certain extent.

All the other organs are mated, and are rarely united by their own proper substance. They are connected in various ways. Thus the kidneys lie on each side, and are united above by the blood-vessels, and below by the ureters, Avhich go to the bladder. The lungs are joined abor'e both by the trachea and pulmonary blood-vessels, while the extremities are perfectly insulated, or at least are united only at their upper ends, Avhere but a small number of parts are found belonging to them in c-ommon,(f )

(1) See a note by ,T. P. Meckel, on the differences between the rig-lit and left portions of the body, in respect to the proportional size of the arteries and veins, in Devtsches Archiv. J'Ã¯ir die Physiologie.^ vol. i. p. 450.

isji 25. 2. Tlio sipnmetni of the dipper and lower parts of the body is less than than that of the lateral portions ; but it cannot be mistaken.

It is especially seen in the pectoral and abdominal members, where it is indicated by the number of subdivisions which they include. The form and number of the parts of the different systems, which contribute to form the members, are the same in all, except some slight differences, which depend for the most part upon the difference of functions performed by the superior and lower extremities, so that one caanot doubt but that these are constructed after the same type, even in man. The upper and lower regions of the central parts of the whole body also correspond, when the head and trunk are supposed to be united. To the central part of the vertebral column alone are attached peculiar and distinct bones, called ribs. Next come, above and below, vertebrÃ¦ without ribs ; above are the cervical, below the lumbar, the number of each being less than that of the dorsal. To the former is annexed the head, to the latter the sacrum, which is, like the head, an aggregation of large vertebrÃ¦ ; these are similar to each other, partly in their increase of size, and also because they unite more slowly, and sometimes do not fuse upon the median line, because the number of pieces of which each is composed has become more considerable, because they are more solidly united to each other ; and finally, because they are fused together, and articulate with moveable bones â€” the coccyx below, the lower jaw above. Hence, we may consider them as imperfect vertebrÃ¦, since the first represents the arch, the second the body of the vertebra.

The upper and lower parts of the body correspond manifestly also in the energy with which hair is there produced. We may especially compare together the hairs of the beard, of the nose, and genital parts, which surround the upper and lower openings of the intestinal canal, and the apparatus connected with it, since they appear in the same places, and are or are not developed under the influence of the same conditions.

But the two extremities of the intestinal canal, and the organs which are there annexed, also correspond.

The intestinal canal commences above by a considerable dilatation, the buccal cavity and the pharynx ; next comes the esophagus, the muscular parietes of which are attached to the adjacent bones, and are susceptible of voluntary motion. The same arrangement is observed in its inferior extremity, the rectum, which continues above with the colon. The parietes of those two extremities also are provided with very strong muscular fibres. The same thing occurs a second time in the remainder of the alimentary canal, and two new expansions are remarked ; the superior is the stomach, which is continued with the small intestine ; the inferior, the colon, and still farther, the cÃ¦cum, which opens in the same manner with the large intestine.

Farther, in the upper and lower parts of the body there are several organs which manifestly correspond. The respirator}' apparatus may be compared with the urinary apparatus ; and the thyi'oid and thymous glands, the tongue, and the nose, correspond to the genital parts.

The first comparison is estabhshed more easily than the second. The principal organs of the two apparatus, the lungs and the kidneys, are similar : first, in number, they are two ; second, in situation, they are separated one from the other â€” are not inclosed in a common sac, and are placed along the vertebral column ; third, in their mode of connection ; for they are united by large vessels which enter them, and canals which come from them,' all of which are united on the median line, the lungs by the trachea, Ã„nd the kidneys by the ureters and urethra ; fourth, by their structure ; apart from the general conditions presented by the texture of the glandular organs, the formation of the cellules of the lungs is represented by the size of the vessels which secrete the urine, and of the large or small cellules socommonly found in the kidneys.

The genital parts and the other organs may be compared, and a parai â– lei drawn between them from structure and functions. The thymous gland, which is composed of two lateral lobes more or less e\idently separate, corresponds to the ovaries and testicles in its glandular structure, and in its situation, since it is the deepest of all. The thyroid gland, an unmated^ organ, is placed much higher and more externally, and represents the prostate gland with the vesiculÃ¦ sÃ©minales, and the uterus. The external and internal form of the tongue, the abundance of its vessels and nerves, the development of these vessels and of these nerves in papillÃ¦, the nature of its epidermis and, finally, the arrangement of its muscles, vessels, and nerves, resembles the glans penis, and clitoris. So, too, with the nose and larynx ; the first may be compared with the urethra and vagina, in regard to its structure, its texture, and its functions. With regard to the larjmx, the powerful influence of the state of the genital parts upon the bosom and on the voice, aheady assures us that we may compare it to these organs, but as it fulfills peculiar functions, we ought not to expect to find in the lower half of the body any thing exactly corresponding to it.

Besides the analogies already indicated between the upper and lower halves of the body, they correspond ; o. in the arrangement-of the vascular system. The aorta and venÃ¦ cavÃ¦ are distributed in almost the same manner, and form, above, the vessels of the head and upper extremities, and below, those of the pelvis and lower extremities.

b. In the arrangement of the nervous system : the cerebral nerves, and even one of the spinal nerves proceed from behind, forward, while the direction of those of the spinal cord, except the upper, which move somewhat obhquely, is from before, backward. The spinal marrow, after gmng off the spinal nerves, is prolonged, and sometimes bulges like a button, which corresponds to the brain.

c. In the aiTangement of the muscular s3stem ; since several of the muscles of the back and belly are repeated in the upper and lower parts of the body.

We have already remarked that the greatest analogy exists in the arrangement of all the systems which unite to form the extremities.

The diaphragm forms between the upper and lower parts of the body a partition resembling the median line. (Â§ 24.)

Â§ 26. 3. The more obscure analogy between the anterior and posterior faces of the body is generally neglected for that which is seen in the two directions above mentioned. However, we must point it out, although the external face of the body offers but few faint traces of it.

The vertebral column is evidently represented on the anterior face of the body by the sternum, since this bone closes the cavity of the chest before as the vertebral column closes it behind. The sternum corresponds particularly to the centre or pectoral portion of the vertebral coi)imn ; nevertheless, it extends both above and below, beyond the cartilages of the ribs with which it is united, and as it is shorter than the pectoral portion of the spine, so that, in regard to one dimension, it represents only an imperfect spine, the upper and lower extremities, which do not support any ribs, are incomplete imitations of the cervical portion and of the lumbar portion of this column.

The costal cartilages represent also the false ribs, since they remain always behind the true ribs, either in their smaller size or in their texture and chemical composition.

In the anterior part of the abdomen there are no bones to correspond to the vertebral column ; but the linea alba, that strong tendinous cord which extends along the median line from the sternum to the pubes, certainly represents it.

The internal mammary and epigastric vessels on the anterior face of the trunk, correspond to the large vascular trunks which descend along the vertebral column ; and the medulla which passes through the spine, resembles the grand sympathetic nerve situated before this column. This law is recognized also in the doubleness of each lateral half of the spinal marrow which is itself composed of an anterior and a posterior cord, in the existence of an anterior and posterior series of roots of the spinal nerves, and in the division of the encephalon into the cerebrum and cerebellum. In the same manner the frontal and occipital bones correspond before and behind. In the spine, the arched ribs before, resemble the vertebral arches behind, and the more so, as the latter are developed by separate points of ossification.

The analogy extends also both to the trunk and limbs, between the extensor and flexor muscles, in respect to number, size, form, situation, and mode of insertion.

Â§27. We have said above (Â§ 23) that the symmetry is not perfectly regular. We have explained the possibility of this fact, and its reality is already in part proved by the details into which we have entered. A glance at the different systems, and at the different regions, will prove that the differences we have mentioned really exist. The osseous and ligamentous system, as also that of the voluntary muscles and the nerves associated with them, appear to be essentially formed of two exact halves, which correspond so closely, in volume, form, and situation, that they are almost perfectly similar. On the contrary, the vascular system, the grand sympathetic nerve, the organs of respiration, of digestion, and of the uime, are not symmetrical. The heart is not placed perpendicularly but obliquely, so that its septum does not correspond to the axis of the body. In its two portions we see the same divisions and the same general arrangement ; but they differ much in capacity, and in the thickness of their parietes. The vascular trunks which belong to these two parts correspond neither in external nor internal form, nor in destination. The vascular system, considered as a whole, is composed of four trees united by the heart ; these are the arteries and veins of the body, and the arteries and veins of the lungs. The first two trunks, as well as the last two, accompany each other, but neither the two parts of each tree, nor the portions of different trees which proceed together, perfectly resemble each other. The trunk of the aorta is not placed exactly on the median line, but is found, first on the right, and then on the left of the vertebral column. Hence it is arched. From tins arch the carotid and subclardaii arteries arise by a common trunk on the light side, while they have separate origins on the left. The large vessels of the right and left sides are very seldom ahke in then origins, volume, and rout. The two venÃ¦ cavÃ¦ inchne to the right ; on the same side we find between them the azygos vein to which the small vein of the same name corresponds, but imperfectly on the left side. The two arteries of the heart arise each by a single trunk from their respective ventricles ; but the pulmonary veins, when they alive at then auricle, are four in number, while those of the body are only two. So, likewise, we almost always see three or four veins corresponding to a single secondary arterial trunk.

The two lungs have neither the same volume nor the same form : the right lung is larger than the left, and is composed of three lobes ] and its bronchia is shorter, but broader. For this reason, and also on account of the obhquity of the heart, the anterior mediastinum is directed obhquely fi'om above downward, and from right to left.

If we extend our observations to the digestive system, we see the esophagus inclines more to the left than to the 'right, and that the stomach occupies the left side, whence it extends obliquely to the right, and near its left portion is the spleen, which, even when connected with the pancreas also situated more to the left than the right, corresponds but slightly to the liver, which, with its voluminous mass, fills all the upper parts of the right portion of the abdomen. The mesentery extends from above downwards, and from right to left. The large in testine continues with the small mtestine, not on the median line, but on the right side ; its right and left halves do not correspond. The kidney and capsula renalis of the right side are situated lower than those of the left, and have not exactly the same form ; their bloo'd-vessels and their excretory ducts are rarely arranged in a similar manner. The genital organs are more symmetrical ; nevertheless, one testicle is sometimes larger than the other, and sometimes one remains in the abdomen, when the other descends into the scrotum. The direction of the womb is often oblique, which does not arise from accidental circumstances.

The least symmetrical organs correspond, however, in this respect, that they are formed at least of two similar halves. The digestive apparatus presents so little symmetry only because this want of symmetry is necessary from its length, and the functions it executes. Its whole extent may be divided into two nearly similar parts, which, setting aside its cylindrical form, are well indicated by the arrangemerrt of the vessels. In fact, in almost its whole length, that portion of its circumference which is turned towards the mesentery, and in some parts especially, as the stomach, two opposite portions of the same circumference receive vessels which ramify uniformly, and which, proceeding each upon one of the portions of this canal, anastomose opposite their point of commencement.

Hence why the lateral parts of the least symmetrical organs resemble each other so much that the lateral symmetry is more perfect than the others, and the parts which coiTespond laterally execute precisely the same functions. Hence especially this more distinct symmetry, which in several respects, is indicated in other directions so obscurely that it is not perceived by one unaccustomed to tracing analogies, and who knows not how important it is to determine them when we wish to explain the cause of the phenomena of formation.

But the want of perfect symmetry may usually be explained by tjie law above mentioned, (Â§ 23,) and, in accordance with which, one of two opposite correspondmg parts is almost always more developed than the other. All the right side is larger than the left. The right portion of even the most symmetrical organs is larger than the left. The larger lung and the liver are placed on this side. The common trunk of the right carotid and subclavian arteries seems to be produced by a greater energy of the formative power. The cerebrum develops itself at the expense of the cerebellum, and the inferior part of the spinal marrow otfers hardly a trace of expansion which may be regarded as corresponding to the brain. Where such marked differences exist, we see another organ very largely developed in the parts where the system is so considerably diminished, of which there is scarcely a trace on the opposite side. The spinal marrow terminates rather high in the vertebral column, although we see appear in the pelvis, and in front of the sacrum which corresponds to the cranium, (Â§ 25,) a special apparatus, that of the genital system, which very much resembles the nervous system in structure and functions.

On the contrary, on the opposite side, at the upper extremity of the body, where the brain so remarkably predominates, the generative system is but imperfectly indicated ; for, first, the different parts here situated are not united in a single body, as constantly happens when the development of parts, which, if regularly formed, constitute a whole, is disturbed and cannot be perfected ; secondly, these different parts have not a common function, since the tongue belongs to the digestive, and the nose to the respiratory system, while the thyroid and the thymus glands are not included in any.

The differences between the organs which are here compared are such as to oblige us to enter upon a more profound examination, in order to prove that the analogy established is not forced. We have said that the genital system corresponds, partially at least, with the brain, or, perhaps more exactly, with the nervous system.

Our arguments are :

1st. This proposition is rendered very probable by the functions of the two apparatuses. The nervous system is the principle of all life and of all formation in the organism. The existence of the individual is more closely connected with the integrity of its central parts than with that of any other organ. A similar relation exists between the principal parts of the generative system and the life of the species. We may even, and with justice, say that the generative system has the same effect on the formation of the individual, when we reflect upon the remarkable modifications its presence or absence produces in the activity of the mind and of the body.

2d. The form of these two systems argues in favor of this opinion. The remarkable exception made, by the perfect symmetry of the genital organs, to the common arrangement of the other organs with which they have some affinity, must be mentioned. The round form of the ovaries and testicles also furnishes a point of comparison. The texture of the testicles and brain is very analogous, since both are formed of very delicate fibres, similar in flavor and chemical composition. The dura mater forms septa between the two hemispheres of the brain, and between the cerebrum and the cerebellum, which partially resemble the septum of the scrotum, and partly those found in the substance of the testicle, which are fonned by the prolongation of the tunica albuginea. The corpus highmorianum, which arises from the testicle by numerous roots, may be compared to the spinal maiTow ; it opens externally on each side by an excretory canal comparable to the nerves, although the brain and spinal niaiTow are necessarily connected with the organs by several rays. But few lymphatics arise from the brahi and the spinal marrow, while very many originate in the testicles, in order to strengthen the influence which those organs biave on the body. We ought also to remark that the arrangement of the blood-vessels in the brain and testicles is very analogous, since in both the circulation of the blood is evidently retarded.

3d. The study of these organs comparatively in the animal series presents still more points of agreement, of which we shall mention only one of the principal, the development of one of the two systems accompanied by the wasting of the other.

We have already stated (Â§ 25) several arguments which justify the comparison established between the genital parts and those organs situated in the upper half of the body, the development of which appears to be restrained in part by the brain, as that of the lower extremity of the spinal fnarrow is checked by the genital system. It might be objected that the uses of the tongue relate to the functions of the alimentary canal, and so with the nose, which is very intimately connected with the organs of respiration. But on one side, the genital system is only developed out of the alimentary canal ; and again, the senses of smelling and of taste are at least as closely connected with the sexual appetite as with that for food. We shall avail ourselves of this favorable opportunity to explain the difference between the upper and lower extremities of the body, relatively to the arrangement of the two extremities of the alimentary canal and of the organs near them. Below, the canal is entirely separated from the genital and urinary systems blended together ; above, on the contrary, it unites with the respiratory system, and the tongue inclosed in the buccal cavity corresponds to a part of the genital apparatus. This arrangement depends partly on the analogy between the genital and digestive systems, and partly on the fact that the epiglottis and velum palati form septa, which, by changes in their direction, can separate the nasal cavity and the trachea, and consequently the organs of respiration, from the buccal cavity, and even from the pharynx, and necessarily from all the digestive apparatus.

The form, situation, texture, and liability to the same land of disorganization, justify the comparison established between the thyroid gland and the womb, or prostate gland. That the thymus gland corresponds to the testicles and ovaries, is known from its similarity in form, situation, texture, the analogy of the fluid secreted, and the circumstance that its activity ceases when the testicles or ovaries come to maturity.

The differences between the anterior and posterior faces of the body, which we have compared together, are reconciled in the same manner. All the posterior or dorsal half is more completely developed and more strongly marked than the anterior. ' The occipital is thicker than the frontal bone, and the bones of the skull are generally stronger than those of the face. The face is naked, while the skull, especially behind, is thickly covered with hair. The muscles are more numerous and stronger along the spine thair along the sternunr. The sternum is formed like an imperfect spinal column ; as it represents only the anterior part the bodies of the vertebrÃ¦ properly speaking, and corresponds to the lower extremity of the spine, to the coccyx. The linea alba is still more imperfect and feeble. The ribs ossify ; the costal cartilages do not ossify, or but rarely, and at an advanced age. The posterior part of the ribs is, in its turn, much stronger than the anterior. The ribs below the tenth belong properly to the spine. An artery winds on each side along the rudiment of the anterior vertebral column, and corresponds to the aorta, which is placed before the proper spine ; the whole in conformity to the law, that formations of an inferior order are characterized by a want of concentration. ( 1 )

(1) See our remarks on the progressive advancement of the organization, or on the diflerence between the formations of a superior and inferior order, in our BcylrÅ“go zur vcrglciekendcn Anatomic, vol. ii. part 1, Leipsick, 1811.

Notwithstanding these adjustments, corresponding parts, even the right and left halves of the body, always differ essentially. The symmetry is, then, noi perfect. The organization of man has no advantage in tliis res^rect over that of animals, not^vithstanding what Heiland intimates when he says that the dualism (lateral) is particularly marked in the human body.(l) So far is this from being true, that the farther we proceed from man, the more distinct is the lateral symmetry, with a few exceptions. For not only do the organs, which are but slightly symmetrical in him â€” for instance, the heart, some parts of the vascular system, the respiratory system, the urinary system, and digestive system â€” become more and more so as we descend the scale, but even the organs most symmetrical in man, as the nervous system, and the brain especially, become still more so m animals.

Â§ 28. The conditions enumerated form the object of an anatomy, which compares a body wdth itself, considering it only in reference to its different parts. But tlris body may be compared Avith itself, considering it in time, that is to say, in regard to the different periods of its existence.

VIII. JVb organ possesses precisely the same qualities at all periods of the existence of the organism. There are none which are alike at all periods of their existence. Each organ, and consequently the whole organism, passes through certain regular and normal stages. (2) Tlris very important law, called the law of development, gives rise to the following considerations ;

1 . There is for each organ, and for the whole orgairism, a period of imperfection, in which the whole development is irot attaiired ; tlris is called the period of youth, or infancy ; a second called that of mature age, or period of maturity, of perfection ; and a third, that of old age, or of decline.

2. The resemblance is much greater betiveen diff'erent organs, and the diffey'ent regions of the body, the nearer each respective organ, and the whole organism, is to its origin; the more recent the organism, the more symmetrical it is. The heart is, at first, perpendicular ; its septum coiTesponds exactly to the median line, and its two portioirs have the same size aird thickness. The liver projects as much to the left side as to the right ; its left lobe is as large as the right, and its suspensory ligament is on the median line. The stomach is perpendicular. The upper extremities are more simila,r to the lower than at later periods. The sternum is, at first, composed of several cartilaginous pieces, which afterwards become so many bones. Each piece is placed between two costal cartilages, and the latter are always implanted in a groove, hollowed from two pieces of bone. This analogy afterwards disappears, since the osseous pieces, each of which corresponds to a vertebra, fuse together, so as to form only one body.

(1) Loc. cit. p. 5. Walther {Physiologic, vol. ii. p. 102.) is not more correct when stating' that the dualism of the two portions of the body is less evident in the inferior classes of the animal kingdom, and commences to be perceptible only when the nervous and muscular fibres can be distinguished. In fact, the bodies of many animals destitute both of muscles and nerves are evidently formed of two symmetrical halves.

(2) See, in regard to the changes which supervene during 'the first periods of existence till birth, the work of F. G. Danz, Grundriss der 2^gliederungskunde des ungebornen Kindes, Francfort and Giessen, 1792-3; and for the particulars of the structure of the body till the latter periods of life, the dissertation of Seiler, (AnatomiÅ“ corporis humani senilis specimen, Erlangen, 1800.) Consult also Hopfengoertner, Einige Bemerkungen Ã¼ber die menschlichen Entwickelungen, und die mit derselben in Verbindung stehenden Krankheiten, Stuttgard, 1792. â€” A. Henke, Ueber EntwickelungcnundEntwickelungs-KrankheitendesmenschlichenOrganismus,Nuremberg, 1814. â€” C. A. Philites, De decremenio alterÃ¤ homiiium Å“tatis periodo, seu de marasme senili in spscic, Halle, 1808.

Generally, the mode of development of the organs is the same, or at least almost similar, which increases the analogy remarked between diflferent parts and different regions, during the first periods of life. Thus the spinal marrow, and probably also the brain, arise at first by two layers, which are not even united. The intestinal canal forms in Ihe same manner.

The heart is at first only a single cavity, with thin parietes. The cerebrum also exists before the cerebellum, and its parietes are extremely thin in proportion to its cavity. The intestinal canal is a continuation of the umbilical vesicle or of the vitelline sac, as the genital and urinary systems are probably of the allantoid membrane. The extremities of the urinary, genital, and digestive apparatus, are at first blended together, and form a drain. This arrangement certainly exists in the upper end of the body, for at first the palate does not exist between the nose and the mouth, which form but one cavity. The male and female genital organs are more similar in form and situation when studied m the young fetus.

3. The color of the organs develops itself gradually. At first, the whole body is whitish, and even transparent ; it gradually assumes a deeper color, and becomes opaque. Each organ does not acquire its peculiar color till a later period.

, 4th. Every organ is softer and more fluids the nearer it is to its origin ; it gradually acquires its normal degree of consistence, and its cohesion increases till the end of life. Thus, softness characterizes the first, and rigidity the latter periods of life. This law is founded on the fact that all the solids come from the fluids, both at the period of the first formation of the new organism, and during the rest of life. The substance of the organ is not only soft and fluid, but it is also surrounded with an abundant fluid, or if hollow, it contains a liquid, the quantity of which is very considerable in proportion to the thickness of its parietes. The nervous and vascular systems prove this assertion. The vascular system is composed at first only of channels formed in a homogeneous material, and has no distinct parietes. The progressive increase in the consistence of the organs is clearly seen in certain portions of the vascular system, in the uterus, in the serous membranes, in certain organs, as the spleen and some fibrous organs, where an osseous tissue is formed, which is almost regularly developed in them at an advanced age. When the degree of cohesion equals that of the bones, there appears in the mass, at first homogeneous and fluid, a peculiar system, very dense in relation to the others : this is the cartilaginous, which gradually changes to a tissue still more solid, the osseous.

5th. This state of great fluidity is attended with a leant of a determined texture during the first periods of existence. At first we do not see even globules in the organic substance ; these globules then appear, but they are not yet united to form distinct organs ; when this is commenced, fibres are not yet formed. All these circumstances unite to strengthen the resemblance between ditferent organs in the extreme periods of life.

6th. All the organs do not appear at the same time. This proposition is true in regard to the whole system and to each of its different parts. It is more difficult to determine the order m which the systems are developed in man, and in the superior animals generally, which pass very rapidly through the first periods of existence, than in the inferior animals ; and it often happens that organs of great importance do not appear until the growth is terminated ; but we are certain that vessels and nerves are the parts first seen m the primitive homogeneous mass, and that the intestinal canal begins to form almost at the same time. At first, the trunk of the body exists alone ; no trace of the limbs or head is perceived ; next we see the head, then the upper extremities, and afterwards the lower, the parts of which also gradually develop themselves. The organs of sense and of generation are seen at a peiiod still more advanced. The muscles and the bones, especially the teeth, are developed still later. Finally, the dermoid system is the last to form, since a long period elapses during which the nails and hairs, the latter especially in certain parts of the body, are entirely wanting, or are developed but imperfectly. Naturally the similar parts are the slowest to show themselves in the regions which appear the last.

7th. These parts, which are hut repetitions of other more perfect parts, and lohich especially correspond to them, are the last to appear. Thus the sternum and linea alba, do not appear till long after the vertebral column ; the thymus and thyroid glands are formed after the genital organs ; the right ventricle of the heart appears after the left.

8th. The external form develops itself much more rapidly than the texture and chemical composition of the organs. There is no perceptible difference between the gray and the wlfite substance, in most of the cerebral mass, when its parts are entirely formed. A bone, when cartilaginous, has its external characteristic form. But this form differs remarkably at different periods.

Generally, the form is more simple, as the organ is younger. The brain has no circumvolutions nor layers ; and the cartilage forms a homogeneous mass, although the bone is fibrous, and has not the same texture in all its parts. The heart, which afterwards contains cavities, is at first, single, and is formed like a vessel, &c.

9th. The organs arise almost entirely by separate parts, which gradually unite to form a whole. The whole body, the nervous system, the intestinal canal, are, at first, formed of two halves, which afterwards unite upon the median line. The vascular system, at first, forms i.slands filled with a fluid substance, isolated lakes, which, by slow degrees, form themselves by intermediate passages into a canal, with numerous ramifications in their intervals, and gradually give rise to a network of vessels. I'he kidnejis are, at first, composed of several lobes, which are then more numerous than at subseciuent periods. The bones develop themselves by several dilferent points of ossification, which are afterwards united.

10th. Jill the orgcms have not the same proportio7ial volume at evernj epoch of life. The brain, the whole nervous system, the heart, the whole \-ascular system, the hver, the kidneys, and still more tire capsulÃ¦ renales, the thymus, and thyroid glands, are, at first, larger in proportion to the other organs, than they are at later periods.

On the contrary, other organs, the iirtestinal canal, the spleen, the genital parts, and the lungs, remain for a long time relatively small. We also observe certain organs shrink after a time, before others, which, though small at first, had acquired considerable size. This is the case with the thymus gland, which is formed late, and the sexual organs, particularly those of the female.

Hence the respective proportions of parts of the entire system differ very much at different periods of life. The clavicle, so small in the adult, is, at first, six times as large as the humerus and femur.

In virtue of the same law, the mutual relations of different parts of the body do not remain the same at different periods of life. The head, which at first does not exist, soon acquires almost the size of the trunk ; and the hmbs are, for a long time, but stumps, the upper being the larger.

11th. The du7'ation of the oi'gans is not the saisie. For this reason, the organism is not constantly formed of the same number of organs. Some of its parts are temporary, others remain during life. The membrana pupillaris is destroyed before birth ; the membranes of the ovum, the placenta, and umbilical cord, disappear soon after tins period. After a time those portions of the vascular system which coexisted with these organs, are entirely obliterated. A little later the thymus gland becomes smaller, and gradually vanishes ; at twelve years of age we cannot trace it. The first twenty teeth are shed at the age of seven years.

The capsulÃ¦ renales sometimes disappear in old age ; and, perhaps, the same thing occurs with the ovaries.

We may establish it as a principle, that the parts which grow the latest, are those which disappear, or at least those which cease to be active the soonest, and which are most easily destroyed. This is proved by the facility with which cicatrices of the skin and of the bones open again in general diseases.

Marry of the organs which disappear are replaced by new organs. As others serve only to replace those which are not sufficiently active, their disappearance is not necessarily attended with the formation of new parts, and only with an increased action on the part of some aheady formed.

12th. Some systems pass through a greater variety of degrees than others^ not only in respect to texture, but in external form, situation, and proportional volume: the history of their life is more complicated. The vascular system stands first in this respect ; the intestinal canal, with its appendages the genital organs, come next. The osseous system, at different periods of life, varies very much. The differences are less in the nervous system, and still less in the others.

13th. In some parts ive can alicays trace the primitive formation ; in others we cannot, although ive Tinoio not exactly the cause of this difference. Thus, in the adult, we rarely see the four pieces of bone of which the os occipitis is composed, or the two halves which unite to form the frontal bone, or the lower jaw, while the existence of the intermaxillary bone, and the articulation of the mastoid portion of the temporal bone with its squamous and petrous portions, are always very perceptible. Nevertheless, this circumstance may possibly depend on the fourteenth law, and the fact, that the traces of the transitory normal formations, which correspond to the constant formations generally existing in the animal kingdom, are preserved longer than those of any others.

14. The degrees of development through which man passes from birth to the period of perfect matu7'ity, cot'respond to co7istant fomnations in the anhnal kingdom. {!) All the organs prove tliis assertion.

The fetus, m fact, is allied to animals much lower in the scale,(2) from the circumstances of the greater resemblance between the different parts and the different regions during the early periods of life, the smaller number, the uniformity of color, the greater degree of softness, the less distinct texture, the relative difference of volume of the organs, and their production by the union of parts at first isolated. The most general law in this respect is that the organisms which the fetus resembles, are the more inferior, the nearer it is to its origin when the comparison is made ; whence it follows, that the embryo, from its first formation to the time of its maturity, passes through a series of forms more and more complicated.

(1) See our Essay on the resemblances which exist between the fetal state of the S7C~ perior and the permanent state of the inferior animals, in our BeytrÅ“ge sur vergleichenden Anatomie, vol. ii.p. 11., No. l.j Leipsick, 1811:

(2) There is, perhaps, in anatomy no axiom more incontestable than this; but we must

^uard against abusing it, and should not confound analogy with identity. Thus, it IS too much to say that man, from the period of formation to that of birth, passes successively through different forms, which are permanent in the inferior animals. First, this proposition is never true in respect to all parts, but only in regard to some, so that the relations supposed by modern physiologists to exist between the human fetus and reptiles, fishes, csetacese, &c., rest only on analogies, more or less remote, between some of its organs and those of the animals in these classes. Again, we must not forget that the human fetus, from the period of its formation, irresistibly tends to assume the peculiar form of man, and so toe with those of all animals. These remarks seemed necessary to anticipate the forced applications w-hich might be made of one of the discoveries most honorable to modern anatomy, and to keep within reasonable bounds that enthusiasm which exists with us ; for by falsifying the principles of a science we retard its progress. F. T.

The proofs drawn particularly from the organs are :

a. In regard to the vascular system. At first only one system of vessels is found in the embryo, the omphalomesenteric vein. This state of the vascular system corresponds to what is observed in the medusÃ¦ and zoophytes allied to them, in which also only one order of vessels exists : and farther, because the vessels have no proper parietes distinct from the mass of the body. When the development is more advanced, the heart appears as an enlarged point slightly dilated, a little muscular, oblong, channeled, and curved from the vascular system, as in many worms, where, although a complex system of vessels exists, the heart is wanting. Even in the arachnides and the branchiopedous Crustacea, the heart resembles a thin elongated sac, and the vessels arise from its extremities and parietes. At first only one dilatation exists, even as in the most perfect cnistacea, where the heart is contracted to a sort of small quadrangular and muscular cavity.

A later formation, in which a second dilatation is produced by the separation of the auricles with the venÃ¦ cavÃ¦, corresponds to the heart of most mollusca, of fishes, and of the lowest reptiles ; this is more perfect, and presents two cavities, each composed of an auricle and ventiicle ; but here the two auricles and the two ventricles communicate, as the septum between them is irnperfeet. This formation includes also the hearts of certain reptiles, for example, that of the scorpion turtle, and of the lacerta apoda, and as respects the communication between the two ventricles only, that of most reptiles, of those which constitute the upper orders. At first, as only one ventricle exists, there is only one artery, which, as in the mollusca, fishes, and reptiles, commonly arises by a considerable muscular dilatation which is, in fact, a third cavity. The pulmonary artery does not begin to form a distinct trunk till after the aorta, and during all fetal existence these two vessels are united in a common trunk by the arterial canal.

So too in most reptiles, particularly those where the heart is completely developed, we not only recognize two aortas coming from the heart, which meet at an acute angle, and are blended together ; but the pulmonary artery communicates during life with the corresponding aorta by a broad canal, as is evident at least in the turtle. In the plungers, among the mammalia, the communication between the two auricles is so often found open, that it forms a new analogy between the human embryo and animals. A peculiar system, that of the vena porta, which is intermediate between the arterial and venous system, is seen only in the vertebral animals ; as we descend the scale, the veins of the intestinal canal empty immediately into the vena cava inferior. This system of the vena cava is deficient during the first periods of fetal life, and the blood of the iirtestinal canal then returns directly to the heart ; since the vena porta is the first vessel which appears, and the liver is not yet formed. We trace this primitive formation in the venous duct, even when the development is perfect.

b. The nervous system also somewhat resembles the organization of animals.

Ð°. It is formed by the union of two distinct cords, and is similar in this respect to the arrangement in most invertebral animals, in which the two cords which unite one ganglion to the following are more or less evidently separated from each other.

ÃŸ. As at first the spinal marrow exists alone, there also the formation corresponds to that of the most inferior worms.

y. The spinal marrow is much longer at first, and descends lower in the vertebral canal ; even so the medulla dorsalis of worms, of most mollusca, of fishes, of several reptiles, and of all birds, extends to the posterior extremity of the body ; and even in almost all the mammalia it is longer than in man. In the fetus, a cavity extends entirely through it : in the superior vertebral animals, this remains during existence.

Ð±. In the fetus, the parietes of the ventricles of the brain are thin, its surface has no circumvolutions, and the gray substance predominates ; these circumstances are similar to what always exist in reptiles and fishes'. The brain, properly speaking, has no circumvolutions in the mammalia or in birds. The proportion between the gray and white substance is greater in animals than in man. The surface of the cerebellum is indented before that of the cerebrum, both in animals and in man, since this organ is fissured in several fishes, in all birds, and in all the mammalia.

Â£. Finally, both in the fetus and in the animal kingdom, the organs of sense, the appendages of the nervous system, appear very gradually, and these organs in their development present very great resemblances to what occurs in animals.

c. The intestinal canal is at first closed at its upper and lower extremities, as in most of the intestinal worms. The posterior end remains closed longer than the anterior extremity, as is seen in several zoophytes, where the mouth performs at the same time the functions of the anus. At first the intestinal canal is not longer than the body, and enlarges gradually ; so too we see, generally speaking, and with but few exceptions, that it always shortens as we descend in the animal scale. Another analogy also with its mode of development in animals is its greater simplicity during the first periods of fetal life ; since then there is no distinction between the large and small intestines, and the stomach is but slightly distinguished from the rest. The cavities of the nose and mouth are at first united, a little later they are only joined posteriorly, and finally the want of separation between them is expressed by the imperfect union of the upper lip on the median line ; so too the posterior part of the palate is constantly closed in birds, the velum palati is wanting in these animals and in almost all reptiles, and many mammalia have a hare-lip. While the teeth develop themselves very late in the embryo, they never appear in several mammalia, in birds, in many reptiles and fishes, and in most of the invertebral animals.(l)

(1) This defect however is more apparent than real, at least in the mammalia edentata and in birds. Thus J. F. St. Hilaire has remarked that the lower jaw in the fetus of the whale is channeled by a deep fissure, where he found the rudiments of VoL. I 7

During the first periods of fetal existence, an appendage is attached to the ileum, which traces the communication existing anteriorly with the umbilical vesicle. This communication always remains in many birds. Finally, the liver diminishes in size, while the spleen enlarges from the first period of the existence of the fetus â€” phenomena perfectly similar to those found in animals.

d. The sexual parts are at first constructed after the same type, and their primitive form is that of the female.(l ) Afterwards arrives a period when some of these organs, particularly the external, resemble the male form, in all individuals, at least in volume. So several zoophytes and mollusca have only one ovary, which in the former, as in the fetus,

V does not open externally. The testicles of the male fetus remain for a long time in the abdomen ; an arrangement, which is the case during life in all animals, if we except some mammalia. The uterus, in its development, passes through those forms which are permanent in the animal series ; in fact at first it has long horns, which resemble the separation pf the oviducts in reptiles and fishes, and in most mammalia, and reminds us of the great length of the internal horns, in proportion to the body of the organ ; these horns shorten, then the fundus of the uterus is somewhat deepened. Finally the neck is very long and thin in proportion to the body ; the same as the horns of the uterus gradually become smaller in the animals allied to man, and the uterus of many of the apes differs but little from that of the female, except in being thin and narrow. The external genital parts appear late, as in animals.

e. The urinary system, one of those which is formed very late in the animal series, since it is not distinctly seen until we arrive at the fishes, does not appear very early in the fetus. The kidneys are at first united, as in most fishes and many reptiles ; they are also lobed as in almost all reptiles, in birds, and in many mammalia. The number of lobes is greater and their size smaller, the younger the fetus is, as is also seen in fishes, birds, and the cetaceÃ¦, and in the superior mammalia. The kidneys are generally larger in the last three classes of the vertebrated animals than in the mammalia ; but also in the newly born infant they are much larger in proportion to the size of the body than at subsequent periods. We find the capsulÃ¦ renales very much developed in some of the marn)nalia, particularly in the order of gnawers, which also present other analogies with the proper organization of the fetus.

teeth in a substance analogous to that of the gum : these rudiments seemingly disappear early ; for then the fissure closes, and the bone fills up. This anatomist has also recognized in birds the existence of rudiments of teeth reduced to pulpous nuclei, which secrete the horny substance of the beak instead of the phosphate of lime. The same arrangement exists undoubtedly in reptiles of the order chelonia. â€” SystÃ¨me dentaire des mammij'Ã¨res et des oiseaux, sous le point de vue de la composition et de ta dÃ©termination de chaque sorte de ses parties, Parie, \Q2i. F. T.

(1) Muller, De genitalhimevolutione. Halle, 1815, p. 6. D. de Blainville, Remarques sur les organes gÃ©nitaux, in the Bulletin de la sociÃ©tÃ© philomatique, 1818, p. 156,

/. The thymus gland, which in its vital periods is similar to the capsulÃ©e renales, appears late in the fetus, as in the animal kingdom . The mammaha are the first in which it is seen unequivocally ; but it soon after acquires a considerable preponderance, and when the fetus is formed it resembles, in this respect, the gnawers, the amphibious animals, and several plantigrades, in which the thymus gland always remains fully developed.

The thyroid gland is at first formed of two lobes only, which are perfectly distinct, as in most mammalia.

g. The osseous system presents very remarkable analogies, viz. first, in the late period of its development. Most of the other systems are formed when the bones have acquired only a cartilaginous consistence. So, too, almost all the organs are developed in the vertebral animals before we see the skeleton. When the skeleton shows itself for the first time in the cephalopoda,(l) the part first formed corresponds to the bones of the head, which are also the first to ossify in the fetus. But in the former case the skeleton always continues cartilaginous ; so, too, a number of fishes are called cartilaginous^ by which is meant that their osseous system always exists in the state of cartilage ; and in other animals of this class, as also in the reptiles, the bones never advance from the temporary conditions of fetal hfe, i. e. they always remain softer than in animals of the upper classes. In the higher animals the texture and composition of the bones in the early periods of life form a second analogy between man and animals. A third comes from their external form. There is not a single bone which, in the course of development, does not pass through some of the forms which are permanent in animals. This proposition is true, especially in regard to the bones of the trunk and head. In fact the pieces which gradually unite and form the vertebrae, the occipital bone, the temporal bone, the ethmoidal bone, the sphenoidal bone, the frontal bone, and the upper and lower maxillary bones in the fetus, always remain distinct and separate in most animals inferior to man ; and the first periods of fetal existence correspond to the formations, which are permanent when we descend in the animal scale.

h. The external form of the fetus also passes through several inferior formations. The want of distinction between the head and the trunk, itself destitute of the extremities, is manifest in worms and the mollusca, as also the want of the neck after the limbs are developed assimilates the fetus to fishes and the cetaceÃ¦. Many fishes, many reptiles, and even thecetaceÅ“ among the mammalia, also want one or the other of the two pairs of members, and where the limbs appear for the first time in the animal series, they are merely stumps, without fingers or toes, as when they are first seen in the fetus. In no animal is the number of fingers greater than in man, and in many it is less. In many the toes, although the same in number as in man, are, to a certain extent, united by a swimming membrane ; this is another analogy with the human fetus, where the fingers and toes are at first joined together, although one easily perceives that they constitute so many distinct parts. The vertebral column evidently terminates at first in a small prolongation, similar to a tail.

(1) J. P. St. Hilaire thinks that the articulated animals, which form one of the great divisions of the invertebrata, also have a skeleton, but it is placed externally, instead of internally as in the vertebrata : he compares the rings of their bpdies to vertebra and their feet to ribs. (See J. F. St. Hilaire, MÃªm. sur un squelette chez les insectes, dont toutes les piÃ¨ces identiques entre elles dans les divers ordres du systÃ¨me entomologique, correspondent Ã chacun des os du squelette, dans les classes supÃ©rieures; in the Jour, compl. du Diet, des sc. mÃ«d., vol. v. p. 140. â€” Id. MÃ©m. sur quelques rÃ¨gles Judamentales en philosophie naturelle, same collection, vol. vi. p. 36. â€” Id. Rapport sur un MÃ©moire d' Audouin, concernant l'organisation des insectes, ibid, vol. vi. p. 36. â€” Id. MÃ©m. sur une colonne vertÃ©brale et ses cÃ´tes, dansles insectes apiropodes, same collection, vol. vi. p. 138.) This opinion has been adopted by Rudolphi, (TBeytrÅ“ge zur Anthropologie, 1812, p. 89,) and by Carus, {Zeitschrift fÃ¼r die jSatur und Heilkunde, vol. ii. p. 308, 1822 ;) it is well developed in the Dictionnaire classique d'histoire naturelle, vol. V. p. 141., article CrustacÃ©s, F. T.

15th. Ã†an is distinguished from the other animals by the greater rapidity with ivhich he passes through the inferior formatioms. As his organization is the most perfect of ail, he rises above the inferior degrees more rapidly than other animals, doubtless in order to gain time to arrive at his highest perfection.(l)

Â§ 29. IX. Jllthough the form of the human organism varies at different periods of life^ yet it presents certain peculiarities which distinguish it from all others, and characterize the human 7-ace as a separate species. This species, however, is only one of the numerous modifications of the primitive type which constitutes the base of all animal formations, so that its form necessarily resembles, in many respects, those of other animals, particularly those most allied to man. It is then almost incredible that, even recently, several writers would consider many of these conditions of the human form not as results of this law, but as proving positively that, after the original sin, man was even physically degraded from the great excellence he possessed in Paradise ! They pretend that the traces of the intermaxillary bone prove that the cerebrum and cranium are diminished ; they add, that the face is developed in the same proportion, that the plantaris muscle has attained at the same time the aponeurotic expansion of the sole of the foot, and that its actual rudimentary existence proves that men then walked on all fours, &c. All these assertions are unfounded : all these phenomena demonstrate nothing, since it might be proved in the same manner, by the arrangements of some other part, that man, before the deluge, was a different animal from what he is now. The human structure has nothing to distinguish it entirely from that of animals : it ought then to have the same forms ; those presented by it serve to remind us, here and there, of what is found in animals. But these marks, such for instance as the intermaxillary bone, are easily explained by the preceding law ; they trace that series of degrees of the organization through which the embryo, but not the whole human race, always passes ; or they are the vestiges of the primitive state when the human formation was depressed to the level of the animal formation. In order to give some probability to the opinion we oppose, it is necessary, at least, to compare the human skulls before the fall of man and the deluge with each other, and with those of the present time.(l) Nor are there any facts to support a similar hypothesis, the partizans of which pretend, that as the human organism, in accordance with the preceding law, passes through different periods, so this is the case Avith the whole human family ; and that certain races are now at a point formerly possessed by other races at present more elevated, and that these also are capable of gradual improvement.(2) In refuting this hypothesis, we cannot deny but that the different classes of organisms are developed gradually, and in direct proportion to their greater or less degree of perfection.

(1) This law should be called the law of Harvey ; for, althoug-h it was long' forgotten and has been completely developed only by the moderns, it was, however, Harvey who founded it, in saying : ÃŸst cquidem, quod miremur, animalium omnium (jmta canis, equi, cervis, bovis, gallinÃ¦, serpentis, hominis deniqve ipsius) primordia tarn plane galbce figuram et consistentiam referre ut oculis internoscere nequeas. {De generatione, Amsterdam, 1662, p. 77.) This law is of general application to the whole organic kingdom. We must, however, distinguish it from the false law of Harvey, of which we shall soon speak.

To determine the special conditions of the human organization, we can bring together the characteristic marks which distinguish it, so far as they depend on the conditions of the forms of the different parts ; and also those drawn from the form of the whole body, and use them to trace a general picture.(3)

We become acquainted with the marked characters of the human organization, by studying, successively, the different systems and the different apparatuses.

Nevertheless, before proceeding farther, we should observe, that most of these characters distinguish man only from those animals which are the nearest to him, as the other mammalia.

1st. The mucous tissue of man differs from that of almost all other arrimais by its greater softness; perhaps the power he possesses of living in all parts of the world, and the frequent anomalies presented by his organization depend on tliis.

(1) The following' passage from Ackermann, (De naturae humanÅ“ dignitaie, Heidelberg, 1813,) will show that we have not misrepresented him, as is, unhappily, too often done : â€œ Fuere lempora, quÃ¦ antediluviana dicimus, ubi ita despecta et abjecta erat humana species, ut brutorum animantium natures non cequivaleret tantum, sed et infra earn deprimeretur. Argumenta ultra omne dubium elata nobis exhihet anatomica corporis kumani perscrutatio. Reperimus enim per totum corpus non rara vestigia degeneratcB in brutorum naturam humanÅ“ fabricÅ“, ita ut inter multasrariores excitem species... Os intermaxillare, aperto indicio ; aliquando in homine maxillas, uti in brutis magis versus anterioraprotrusas fuisse, cranii recedentis amplitudine diminuta... Musculus plantaris pedis... argumenta, [aliquando hominem extremis digitis incessisse quod alio modo fieri non potuit, nisi etiam priore extremitate corpus suffultumfuerit.â€ Who is not reminded of Stephanus and ^Ivius 1

(2) See Schelver's Memoir â€œ On the primitive race of the Human Family," in Wiedemann's Archiv fÃ¼r Zoologie und Zootomie, vol. iii. p. 1. No. 4. Sehelverand Doornik pretend that all the races are formed by gradual improvement from the negro race. Pallas had already presented this opinion as a probable hypothesis. F. T.

(3) The distinctive characters of the human race have been well defined by Blumenbach, (De Generis humani varietate nativÃ¢, Goettingen, 1795, p. 4. 46.) â€” See also W. Lawrence, Dectures on Phys. ZooL, and the Nat. Hist, of man, republished at Salem, 1828. â€” Caldwell, Thoughts on the Original Fnity of the Human Race, New York, 1830.

2(1. The vascular system. The obliquity of the heart, the inclination of its apex to the left, and the adhesion of the lower face of the pericardium to the centre of the diaphragm, are characteristics of man, or at least are possessed in common with him only by a small number of apes, which resemble him very much.

There are but few animals, too, in which the vessels of the head and superior extremities arise, as in man. The distribution of the vessels is not the same â€¢, we distinguish the want of the rete mirabile i. e. of a plexus formed by the internal carotid artery before entering the eye ; if this be not peculiar to man alone, it serves to distinguish him from a great many animals. We may also mention here, the arrangement of the thyroid arteries, which are two on each side in man, while in the other mammalia we find only one, &c.

3d. The nervous system of man differs from that of other animals in the remarkable size of the brain. Nevertheless, as a comparison of the brain with the rest of the body does not lead to exact results, either when we regard its weight, or consider its volume only, it is more convenient to contrast the encephalon with the spinal marrow and nerves. In doing this, we find the relation to the brain more favorable in man than in any other animal ; and we discover that, in him, the brain is larger in proportion to the spinal marrow and nerves.(l)

At the same time the spinal man'ow in man is proportionally thinner and shorter than in all other animals ; since, in him, it occupies only the greater part of the vertebral canal, while in animals, with few exceptions, it fills all this canal.

If we compare the different parts of the encephalon, we find also, that man is distinguished fi-om all other animals by the greater volume and development of the cerebrum in him, which predominates over all other parts of the nervous system.

The upper and anterior part of the brain principally exceeds those portions which relate to the organs of the senses. To the first law then is attached a second, viz. That the cerebrum, properly speaking, is very much developed in proportion to the organs of the senses.

There are also, or at least they state as such, other characters peculiar to parts of the encepholon, viz.

1 . In the brain ; the existence of the small calculi of the pineal gland,(2) which are not constant except in man, but which exist also in the buck, and which are sometimes deficient even in man, as in old persons. (3)

The greater development of the cerebrum, properly speaking, is attended also with the presence of parts peculiar to man, as a special dilatation of the third cerebral ventricle, the third horn, and the eminence inclosed by this cavity.

(1) SÅ“mmerring', Von Baue des menschlichen Koerpers, vol. i. p. 85. â€” J. G. Ebel, Observationes nevrologicÅ“ ; in Ludwig-, Scrip, neurol. minor, vol. iii. p. 148.

(2) IjsignolÃ®), De lapillis vel prope. vel infra gland, pineal, sitis, Mayence, 1785.

(3) Wentzel, De penitiori cerebri structurÃ¢, p. 156.

The spinal marrow of man presents this peculiarity, that when perfectly developed, it is completely solid. In other animals we see along its centre a cavity, but in man, this does not exist always, being soon obliterated.

2. In the organ of sight, a. The vicinity of the eyes which are still nearer each other in the ape.

6. The absence of the membrana nictitans, although its rudiment - exists in the inner angle of the eye, where it forms a semi-circular fold.

c. The absence of the suspensory muscle of the eye, a character which belongs also to the apes, but which, with this exception, distinguishes the organization of man from that of all other animals.

d. The existence of the eyelashes, although these are found in some mammalia, and also in some birds.

3. In the organ of hearing, a. The existence of the lobe of the ear, which is also seen in some apes, but in them it is much smaller.

b. The immobihty of the external ear ; this last, however, is not general, and is seen only in civilized people, and may be ascribed to a want of exercise : on the other hand it is common also to the anteater.

4. In the organ of smell, a. The projection of the nose over the mouth, and generally its prominence, a character to which, notwithstanding its generality, the simia rostrata is an exception, not to mention the trunk possessed by several mammalia.

h. The want of an organ hke a sack, which has been lately disco vered in all the other mammaba on the floor of the nasal fossae, and necessarily the absence of a communication between the buccal and nasal cavities, the foramen incisivum, which always exists in the other mammalia.(l)

c. In the organ of touch. The smoothness of the skin, which arises from the fewness and shortness of the hair. It is well proved that no part of the skin of the ape is more naked than that of man ; but the skin of the cetaceÃ¦ is undoubtedly less hairy than the human skin. The abundance of hair on some of the South Sea Islanders approximates the skin of man to that of the other mammalia.

4. The osseous system.

1. In the head we remark,

a. The proportion between the skull (cranium) and the face (facies). (2) The excess of the former over the latter distinguishes the human organization from all others. It exists because the br^in is much greater in proportion to the other parts of the nervous espe cially the nerves and the organs of sense, as the skull is designed particularly for the brain, while the organs of the senses of sight, smell, and taste, are situated in the face. We may also separate from the brain-case that part of the head designed for the organ of hearing, inasmuch as the temporal bone which contains it is situated at the base of the skull ; and secondly, its squamous portion, which is appropriated to the sense of hearing, is always separated from that part, and concurs to form the brain-case ; thirdly, the Eustacliian tubes unite the organ of hearing with the buccal cavity, consequently with the other organs of the senses. This mode of considering the subject is justified still more by comparative anatomy.

(1) See the Description of an organ observed in the mammalia by Jacobson, confirmed by Cuvier, in the Annales du MusÃ©um, vol. xviii. p. 412 â€” 24.

(2) G. H. Crull, Diss. de cranio ejusque adfaciem rationc, Groningen, 1810.

The skull also exceeds the face in size, from the predominance of the brain over the organs of mastication, with which the greater development of the organs of taste and smell coincides. The projection of the jaws forward and the retreat of the forehead, which is a consequent of it, have given rise to the facial angle of Camper.(l) This angle is formed by the union of two lines, one of which, called Camper's facial line, descends from the most projecting part of the forehead, along the edge of the upper incisors, and the second is parallel to the base of the cranium, and passes by the external auditory passage and the inferior edge of the nasal passage. It is evident that as the jaws retreat, and the forehead projects, the angle enlarges, although for several reasons it does not indicate precisely the relation of the face to the skull considered as the brain-case.

b. The situation of the occipital foramen. In man this foramen is found exactly or very nearly in the centre of the base of the skull ; so that the centre of gravity of the head corresponds to its centre of motion when the head rests on the base of the skull : a circumstance very important in regard to the question of the erect posture of man. (2)

c. The arrangement of the upper jaiv. Its anterior and internal part, m which the incisors are inserted, constitutes in animals, with the exception only of some apes, a bone, which remains distinct through life, and is called the intermaxillary bone,(os incisivum s. intermaxillare.) (3) This portion however is entirely separate from the rest of the bone in man also, but only during the early periods of existence ; and in the intermaxillary fissure we can always trace more or less evidently the peculiar formation of animals. (4)

d. The shape of the dim, which in animals retreats more or less behind the alveolar processes, while in man it projects slightly before them.

(1) P. Camper, Diss. sut les variÃ©tÃ©s 'naturelles qui caractÃ©risent lu physionomie des hommes des divers climats et des diffÃ©rcns Ã¢ges, translated by Jansen, Paris, 1791 . â€” See also Stuart, De mensch, zoo als hij roorkomt op den bebenden aardool, Amsterdam, 1802, p. 51. â€” Wiedemann in Archiv fÃ¼r Zoologie und Zootomie, vol. i. part 1. p. 18. â€” J. E. Doomick, Wijsgeerig natuurkundig onderzoek aangaande den omssprongliken mensch en de oorsprong liiie stammen van deszelfs geslacht, Amsterdam, 1808.

(2) See the memoir of Daubenton, Sur les diffÃ©rences de la situation du grandtrou occipital dans l'homme et dans les animaux, in MÃ©m. de l'AcadÃ©mie des sciences, 1764, p. 568â€”575. P. T.

(3) G. Fischer, Ueber die verschiedene Form des Intermaxillarknochens in verschiedenen T'hieren, Leipsick, 1800.

(4) Goethe, Zur Naturwissenschaft Ã¼berhaupt, insbesondere zur Morphologic, Stuttgard, 1820, p. 201.

e. The position of the teeth, in two respects ;

a. These bones in man form an uninterrupted series, while in animals, except the anoplotherium,(l) we always observe a vacuum, caused either for the greater development of the canine teeth or by their absence.

ÃŸ. Man is almost the only animal in whom the direction of the incisors is perpendicular to that of the two jaAvs.

2. The trunh also furnishes some distinctive characters :

o. The pelvis in man is peculiarly formed. With a few exceptions, the human pelvis is the only one which appears as a low, spacious cavity, surrounded by broad parietes, or as the bottom of a reservoir.

b. In man also the bones of the vertebral column, from above downward, increase considerably in volume, although generally the spinous processes, particularly of the thoracic vertebrae, are proportionally shorter than in animals.

c. The sternum. When man is perfectly developed, the sternum is formed at most but of three bones ; while in the other mammalia its parts are very numerous, equaling the number of spaces between every two true ribs ; an arrangement which is also regular in man at certain periods of life.

5. The muscular system in man differs from that of other animals by the slight development of some muscles and the greater power of others.

The muscles least developed are those which move the skin ; the most vigorous, on the contrary, are those which serve to maintain the erect attitude, and those which prevent the inferior part of the trunk and the lower extremity of the thigh from bending forward, that is, principally those of the haunch and of the calf of the leg. The muscles which move the head are also more developed in other mammalia, both on account of their proper attitude, and because they serve to sustain the head, and to bite.

The composite systems and apparatuses present the following peculiarities :

1st. In the intestinal canal, the vermiform appendix of the cÃ¦cum is in some measure a distinctive character of the human formation. But the vesicula umbilicalis is not confined to man only, since the tunica erythroides which is found in all the mammalia, at least at certain periods, and the vitelline sac of birds, reptiles, and of many and probably of all fishes, correspond to this organ.

2d. In the genital apparatus, the separation which takes place soon after birth between the serous sac of the testicles and the peritoneal sac is a character which belongs exclusively to the male ; for the canal of communication between these two cavities is never obliterated in the other mammalia. In the female, the external form of the womb, the tissue of this organ, and the presence of the hymen, have been considered as so many particulars belonging exclusively to the human race ; but this is false in regard to the hymen,* which has been found well developed in several other mammalia, or at least is always indicated by folds.(l) The other two characters are more valuaWe : 1. In fact the womb of most mammalia is not single and pyriform both externally and internally, like that of the female ; but it has two horns, and frequently is completely divided into two cavities. 2. It has also a distinct red layer of muscular fibres, vdrich is attached to the internal membrane only by a loose cellular tissue, and its parietes are very thin in proportion to its cavity, while the fibrous texture of the human uterus is developed only during pregnancy ; even then the fibres of this organ do not assume the peculiar appearance of those of the muscles ; it is difficult to separate the internal membrame from the rest of its tissue ; and its cavity is always very small in proportion to the thickness of its parietes.

(1) Cuvier, Ann, du MusÃ©um, vols. iii. and ix.

Neither are these conditions exclusively peculiar to the human race ; for they are found in almost all the edentata and tardigrada ; besides, the womb of the apes and makies differs but little from that of woman.

Â§ 30. The principal character of the human species is drawn then from the large size of the brain, from the inferior development of the organs of sense, and their almost uniform development.

It is in this sense only that we can admit the proposition of Herder(2) so often repeated by others, that man is but a species intermediate between those beings above and below him.

Â§ 31. From the many particulars already mentioned, and from those which remain to be examined, may be deduced a fundamental characteristic of the human species, viz., that originally, and from his very nature, man was formed for the erect posture. The ancients understood this law perfectly well, and showed more sagacity in developing it than many modern writers have in opposing it. (3)

Â§ 32. X. Notwithstanding the peculiarities of conformation which prove that man, like every other organism, forms a separate species, daily observation demonstrates that, under any relation, all the individuals are not exactly alike.

The principal difference, which extends to the whole species, is the distinction of this species into two sexes,(4) male and female. This in fact does not exist, or is not marked so distinctly, in the early periods of fetal existence ; and as the resemblance of the organism to itself is much greater the nearer it is to the time of its origin, so at this period all the organisms appear formed more exactly after the same type But this difference soon begins to show itself, and although the sexual characters in the general form are not well marked until after the fourteenth year, nevertheless the form of some organs, as the genitals, in the regular course of development soon assumes the characters of the male or female. The two sexes differ from each other both in the size of the body in general and of the organs in particular, and also in the proportion either between these organs themselves or between them and the whole body, as in regard to their external form and texture, physical properties, and the position of their parts.

(1) Cuvier, Anatomie comparÃ©e, vol. iv.

(2) Ideen zur Philosophie der Geschichte der Menschheit, Carlsruhe, 1790, vol. i. p. 103.

(3) Compare Moscati, Delle corporee'differenze essenziali che passano tra la struttura de'i bruti e la umana, Milan, 1770; and against his assertions, G. Vrolik, De homine ad statum gressumque rectum per corporis fahricam disposito, Leyden, 1795. â€” G. Bakker, Natuur-en geschiedkundig onderzoek aangaande den oorspronglijken stam van het menschelijk geslacht, Harlem, 1810. â€” The opinion of Moscati has been maintained by Schclver and Dooruik, and contested by Blumenbach, Herder, Vrolik, and Bakker.

(4) Hufeland, Sur V Ã©galitÃ© numÃ©rique des deux sexes dans l'espÃ¨ce humaine, in the Jour, cÃ´mpl. du Diet, des Sciences MÃ©d., vol. vi. p. 361.

1st, In size. The male is usually taller than the female. Some organs are proportionally larger in the male, and others in the female. Besides the differences in this respect between the different parts of the genital organs, for the mammÃ¦ of the male are less developed than those of the female, and the uterus is larger than the prostate gland, and again, the testicle is more voluminous than the ovary, and the penis than the clitoris : independently, we say, of these differences, the heart, lungs, and organs of voice are larger in the male, while the liver, and the brain considered proportionally to the nerves and the whole body, are larger in the female. The hair of the head is more developed in the female than in the male ; in the latter there is a strong beard, and the whole body is hairy, which is not the case in the female, except on the head and pubis.

2d. In the external form. The number of parts is the same in the female, but they differ somewhat in form, for if the stomach in the female is more oblong, and in the male rounder, the form of the body of the female, and usually that of all the organs, is rounder than in the male where the outline is sharper and more angular.

In fact all the parts of the genital apparatus correspond in the two sexes ; but their external forms vary so much that it seems at first impossible to believe that the genitals of the two sexes are only modifications of the same primitive type. In this respect the distinguishing characteristic is the predominance of length in the male, and of breadth and thickness in the female. It is seen both in the form of the genital organs and in that part of the body which contains them. Thus the male pelvis is narrower, more contracted, and deeper, than that of the female ; the penis is longer and narrower than the vagina and clitoris, the vasa deferentia are longer than the Fallopian tubes. The two sexes differ also as respects their constancy of form, which is much greater in the male than in the female.

3d. In texture and physical qualities. The body of the female is usually more delicate, softer, and less firm than that of the male.

4th. The situation of the parts is the same in both sexes, if we except those organs which relate to the generative functions. The principal difference in this respect between the male and female is, that the parts are external in the male, but internal in the female. The testicles are situated externally, and the ovaries internally, the prostate is at the outlet, and the uterus within the cavity, of the pelvis ; the penis extends along its external face, while the clitoris and vagina are placed within its cavity.

Â§ 33. Besides this grand fundamental difference, which divides the human species into two halves, there are others less striking which are common to both of these halves, which distinguish the species, not into sexes, but races. They are called, differences of races. {!)

The characters employed to establish the principal divisions of the human family may be very different, but the suitable track to follow is that which embraces the whole organization, and is not confined to the consideration of only one or another of its peculiarities, as, for example, the color, size, the proportions of the different parts of the body, &c.

Buffon was the first who proceeded in this manner, and divided mankind into six races, viz. the Hijperborean., or Laplander, which includes the polar nations : 2d, the Tartar, which is the largest, and inhabits central Asia ; 3d, the Southern Asiatic, which embraces also the South Sea Islanders ; 4th, the European : 5th, the Ethiopian : and 6th, the American :{2) but, finally, he reduces these six races to five only, considering the Laplanders as degenerated Tartars, and indicating very precisely the tribes which make the transition from the Tartar race properly so called, to those imperfectly developed nations who live under the poles.

After this correction, the five races established by Buffon, correspond to those of Blumenbach, as the Laplander and the Tartar of the first are the Mongolian of the second ; the Southern Asiatic corresponds to the Malay, and the European of Buffon is the Caucasian of Blumenbach ; the similarity of names identify the other two.

Â§ 34. The principal characters which distinguish the European, or the Caucasian, race from the others, are as follows :

A white skin, but in the people of the south it is brownish yellow ; cheeks red, but they have little or no color in the other races. The color of the hair varies, from a light yellow to a deep brown, and even black. The eyes, that is to say, the hides, are blue, gray, brown, and rarely entirely black. The form of the face is oval, neither very flat nor very angular. The bones are no where very prominent ; neither do the cheek bones ever project much. The forehead is arched, but never retreating ; the nose narrow, the mouth moderately large. The lips do not project much ; the lower projects beyond the upper. The teeth are perpendicular to the two jaws. The chin is full and rounded.

(1) The principal work on this subject is that of Blumenbach, De generis humant varielate nativÃ¢, Goettingen, 1795. Consult also, besides the work of Herder quoted above, A. G. Zimmermann, Geographische Geschichte der^ Menschen und der allgemein verbreiteten Thiere, Leipsick, 1778-1783. G. Josephi, Grundriss der Naturgeschichte des Menschen, Hamburgh, 1799. â€” C. F. Ludwig, Gundriss der Naturgeschichte des Menschenspecies, Leipsick, 1796. â€” J. J. Virey, Histoire naturelle du genre humain, Paris, an IX.â€” Id. Recherches sur la nature et les facultÃ©s de l'homme. â€” C. Gross, Magazin fÃ¼r dieNaturgeschichte des Menschen, Leipsick, I788--I791. â€” S. S. Smith, An essay on the causes of the variety of complexion and figure in the human species, in the American Aluseum 1789, p. 30, et seepâ€” C. Meiners, Untersuchungen Ã¼ber die Verschiedenheiten der Menschennaturen, Tubingen, 1811.

The Caucasian race represents, in some measure, a centre, on each side of which are varieties. In fact, the head, and to a certain extent, the whole body becomes either broader or narrower. The Mongolian and American races are marked by greater breadth, while a lateral compression is seen in the Ethiopian and Malay races.

The principal characters of the Mongolian race, are a yellowish or olive color, between that of wheat and boiled quinces or dried lemon peel ; hair black, short, thin, stiff, and straight ; head almost triangular ; face broad and flat ; cheek bones high and prominent ; forehead very broad and flat ; small flat nose ; cheeks almost round, and plump ; eyelids half closed. The proportion of the skull to the face, is a little less favorable than in the Caucasian race, being about one tenth less. The stature of the northern nations of this race is very low ; the extremities are very short, even in the countries at some distance from the north, which probably depends in part on artificial habits.

The American race is distinguished from the others by a copper or cinnamon color ; hair fine, black, straight, and thin ; forehead low ; eyes sunken; nose slightly flat, although projecting. The face is broad ; the cheek bones are generally prominent, but the different features are not both flat and depressed ; they appear, on the contrary, very full, especially on a side view.

In the Malaij race the skin is brown ; the hair is soft, curled, and abundant ; the head narrow; the forehead prominent ; the nose broad, diverging, and thick at its apex ; the mouth large. The upper jaw projects considerably ; but on a side view the features are well proportioned.

The Ethiopian race is farther removed from the Caucasian in many respects. The color is more or less black ; the hair is short, thick, woolly, fine, hard, glossy, and elastic ; it does not extend itself gradually towards the neck, but terminates suddenly, like a wig. The eyebrows are also curled and thinner ; the eyelashes are much more arched and thicker than in the other races. But these peculiarities are not seen at all periods of life, for at birth the color is whitish, and the hair is long and cmded, but not woolly, and on the back part of the head it continues insensibly to the neck ; this latter is stronger, and the occiput is more feeble ; the occipital foramen is placed a little farther forward and is larger ; the head is narrow and compressed laterally, whence the forehead appears sloping. The cheeks project forward, but not on the sides ; the upper jaw is constructed after the same type, and the cheek bones project, evidently, from this arrangement. Hence the alveolar processes appear narrow and long. The upper incisors are directed obliquely forward. The bones of the skull are very strong and very thick. Of all the human races, the Ethiopian is that in which the proportion between the face and skull is least advantageous to the latter, for the facial angle is only seventy degrees, while in the Mongolian race it is seventy-five, and in the Caucasian, eighty. The surface of the face, compared to that of the skull, is one fifth larger in this race than in the Caucasian. The nerves, especially those of the first, second, and fifth pairs, are also more voluminous, in proportion to the brain. The brain is firmer. We could discover no difference in its color, and the various opinions among authors on this subject leave it doubtful. The lips, especially the upper, are thick and turned upward ; their color is not purely red, but they are bluish black, or at most a dirty rose-red. The chin is more or less retreating. The nose is very thick, and is almost blended with the upper jaw, and it is, moreover, flat, even in young fetuses. The eyes are very prominent, and often so black that, in many nations of this race, we cannot distinguish the iris from the pupil. The aperture of the eyelids is generally smaller than in the Caucasian race, but the globe of the eye is larger, and blackish to about half a line round the cornea, while the rest is yellowish. The rudiment of the third eyelid is greater than in the other races. The external ear is rounder, more analogous to that of the ape, and stands out farther from the head. The muscles of the mouth are more developed ; hence the temporal fossa is deeper, and the semicircular line on the side of the skull is more distinct and prominent. The anterior orifice of the nasal fossÃ¦ is extremely large, and the surface of the pituitary membrane is increased by some irregularities within the nose. The anterior palatine foramen is broader. The teeth are very large and very broad. The pelvis is narrower than in the Europeans. The hands and feet are well proportioned, but flat ; the fingers and toes are long.

The genital organs in this race present some general peculiarities, and some characters which belong only to certain tribes. They are chiefly characterized by their great development ; in males, this is seen in the size of the penis, and in that of the clitoris in females.(l) The nymphÃ¦ are sometimes (2) excessively lengthened, and sometimes, in different nations, even new parts seem to be developed, certain accessory organs, which serve to enlarge the external genital apparatus. (3) All these peculiarities are very remarkable, because they resemble the structure of the ape. In fact, the Ethiopian race seems to form the transition from the Caucasian race, to the quadrumani.(4)

Â§ 35. The number of races can be restricted still farther, by referring to a single type, those which are separated in the same manner, from the middle term of the formation peculiar to the Caucasian race. We should then have only three races. This classification is more convenient, as it is favored by the similarity of customs. Finally, the diferent races not only pass from one to the other by imperceptible shades, but still it sometimes happens that certain individuals belonging to one race, resemble others in many essential respects, and especially in the form of the head. We have before us, at the present moment, the skulls of several Germans, so strongly marked with the characters of the Ethiopian race, that it would be difficult to distinguish them from the skulls of negroes.

(1) VaiUanVs Traveh in the Interior of Africa, in the Mag. merk. Reisebeschr, vol. 2. p.308.

(2) PÃ©rou and Lesueur in the Anatomie ComparÃ©e of Cuvier vol. iv. â€” Barrow in Voigt's Magazin fÃ¼r die Naturlehre, vol. iii. p. 4. p. 792. Barrow, however, pretends that the parts found in the Boschisman woman are prolongations of the nymphÃ¦.

(3) The exhibition of a Boschisman woman at Paris as a Hottentot Venus who died

there, proved that PÃ©ron was deceived in admitting a special organ. The pretended apron, very impropeily stated in regard to the Hottentots, (a^ the true Hottentots are deprived of it, and it belongs only to the Houzouanas, or Boschisman women,) is a prolongation of the nymphÃ¦, developed, if we may so speak, at the expense of the labia externa, which arc hardly visible. Cuvier has shown, that the upper part of the two fleshy lobes which compose this apron, are formed from the prepuce and the summit of the nymphÃ¦, while the rest is only an extension of the nymphÃ¦. See his Memoir on this subject, in the MÃ©moires du Museum, vol. iii. p. 259.â€” Flourens, Notice SUT la VÃ©nus Hottentote, in the Journal complÃ©mentaire du Dictionnaire des sciences mÃ©dicales, vol. iv. p. 145. â€” G. Sommerville, in the Med. Chirur. trans. vol. vii. p. 154. P. T.

(4) Sec S. T. SÅ“mmcrring, Ueber die KÅ“rperliche Verschiedenheit des Negers vom EuropÅ“er, Francfort, 1785.

The form of the whole body, and . especially of the head, evidently proves, that the Caucasian race, is that, in which the human character, the predominance of the brain, is seen most perfectly, and on the con-' trary, the Ethiopian race most resembles the apes. The other races form intermediate degrees between the Caucasian race and the other mammalia. But we have no proof, nor is it even probable, that the Ethiopian race can in time be perfected, and that the other races have already possessed their form, than that the human race has once been formed more perfectly, of which form it is now deprived. On the contrary, there is every reason to think, that the species man was formed last, and that all other beings are so many attempts of nature, before making him. We cannot decide, whether the different races are consecutive modifications of a single primitive trunk, or if the differences be original, and if the number of primitive races, which perhaps appeared at the same time, be not infinitely greater than that of the races afterwards formed, by including several, similar to each other, in some large families ; the second hypothesis however, is more probable than the first ;(1) nevertheless, it does not prevent us from reducing the five races, actually admitted by naturalists, to three.

Â§ 36. Besides the differences of sexes and of races, the human formation presents others of a third kind. These latter are separate from the first, and are common to the whole species, and are found indiscriminately in both sexes and in all the races, although they may be more frequent in one sex, or race, than in another : they are called abnormal formations, or deviations of formation. In fact, the whole body, as well as each particular system, possesses an external as well as an internal form, which recurs oftener than any other, and which may therefore be considered as the rule. This regular form, is, at the same time, if not always, at least in most instances, the most suitable, because it is the most favorable for the performance of the functions. It may then be called the healthy form, or the form in harmony with the health. On the contrary, those which vary from it should be called morbid formations ; first, because they often disturb the functions of the organ, and, according to the nature of the organ, and the manner and degree of the aberration, may even prevent the continuance of life ; and secondly, because the cause of those aberrations from the normal state, is evidently a disease, as most of the alterations of texture result from morbid affections.

(1) See the memoir of Rudolphi On the distribution of animals, in the Beitreege zur Anthropologie und allgemeine ^Naturgeschichte, Berlin, 1812.

These anomalies form the subject oÃ® pathological anatonnj. Nevertheless, it is impossible to separate completely the study of the regular from that of the irregular structure ; so that general anatomy ought to embrace, also, the most important considerations arising from anomalies of texture.(l)

All the abnormal formations are essentially the same ; in the end, they consist in the rarity^ and consequently, in a deviation from the rule. Nevertheless, these formations may be distinguished from each other, either from the size and importance of the organ, or from the influence of the anomaly on its functiÃ§n, or according to the degree of the anomaly. But the differences they present in relation to the qualities of the organs, and to the manner in which they are themselves developed, are still more important.

Many of these anomalies, in fact, affect only the external form of the organs ; others their internal structure, their tissue, chemical composition, and physical properties. Many arise during the course of life, and are accidental, while others are primitive. Alterations of texture are the most frequent, but they are not always accidental. The defects oÃ¯ formation are congenital when they do not depend upon mechanical injury, or on previous alterations of texture.

Â§ 37. The anomalies of form, whether appearing primitively, or after the period when the part affected has its regular form, refer, 1st, to the number, 2d, to the volume, 3d, to the situation, and 4th, to the form of the organs.

1st. In the first respect, an organ may be entirely or partly deficient ; sometimes the defect is original, but it is often, also, only accidental, resulting from morbid actions, which, either mechanically, chemically, or dynamically, have partially or totally destroyed the organ. Thus compression and irritation, arising from tumors, or from the teeth which are cutting, cause even the hardest bones, the milk teeth, to disappear ; by the 'vant of extension, as consequent to a ligature, the blood vessels are obliterated as high as the first branch, furnished by the trunk, in which the circulation is impeded. The acids destroy the most solid parts by solution ; the testicles vanish without leaving the least trace, and often without any known sufficient cause, &c.

We cannot always determine with precision, if a part which is deficient, has existed previously, and has been destroyed, since numerous observations demonstrate, that parts, existing at first, partially or wholly disappear, not only morbidly, but normally. (See page 46.)

(1) These considerations, however, can be pointed out only very briefly, when treating' either of general or of descriptive anatomy. We have made them the subject of a separate treatise, called Handbuch der pathologischen Anatomie, Halle, 1812-16. 3 vols, in 8vo.

Neither is there an instance of the defect of any part whatever which has not been differently explained by different observers.

The reverse of defect or absence^ is a plurality of parts, in which we observe numerous gradations commencing with multiplications of the small parts. This defect of formation is always congenital, or at least the power of the human organism to produce supernumerary parts, is extremely hmited, except during the period when the normal parts are forming. In truth, aU these parts are not formed at once. (See p. 45.) But if we except those which appear regularly after the others, the organism never produces parts in any manner composite, and similar to those which exist in the normal state, unless in conditions analogous to those which the formation of a new organism requires.

2d. Aberrations in regard to mass and volume^ are also congenital or accidental. In this case, the mass and volume is greater or less than in the normal state, and the increase or diminution in mass and volume does not necessarily take place in these two respects at the same tune. An organ may become much larger than usual, without an increase, and even from a diminution in its mass when its tissue is considerably dilated or extended. This is proved by the swelhng of the bones and the dilatation of the hoUow organs.

The abnormal stricture {strictura, coarctatio) of the hollow organs, may even entirely efface their cavities ; this is called obliteration, or atresia, which has been badly driided into true and false.

3. Anomalies of situation are accidental more frequently than congenital. In this point of view, fh'st, sometimes a part is found on the side opposite to that where it is generally placed ; or, second, higher or lower than usual. Third. Sometimes it is peiqiendicular when it should be obhque, or obhque when it should be perpendicular. Finally,it may exist outside of the cavity within which it is commonly found. When this part has only left its usual situation, it is called a hernia, or luxation {luxatio). Herniaiswhen a part usuallyinclosed in one of the three large , cavities of the body, escapes fi'om it. lAixation is when a bone leaves its articular cavuty. Inversion is when the internal face of a part is turned outwardly. Inversion sometimes produces an intussusception or invagination, when the inverted part, or those which envelop it, pass into another cavity, as happens for instance in the intestinal canal, and sometimes it causes z. prolapsus, when these same parts project more or less externally. Every prolapsus is, at first, for a longer or shorter time, only a simple intussusception, w'hich sometimes lasts only an instant ; but an intussusception does not always become a prolapsus.

4th. Anomahes in form, are produced in various ways ; since the varieties of which the form is susceptible depend on the particular character it possesses in the normal state. Thus a rounded part can be oblong or more angular, and vice versa. A single part may be divided into several others, and parts usually united may be separate and distinct. The deviations of formation most often found, are the abnormal separation of parts usually united, and the abnormal union of parts generally separated. But abnormal separation may often, although not always, be referred to defect, or absence, as for example, in fissure of the palate, or of the abdomen. So too with abnormal union, as the fusion of the two eyes into one, the union of the two auricles, or of the two ventricles of the heart, &c.

The anomalies of this class also are accidental, or congenital ; in the latter case, they are probably for the most part primitive or original.

The anomalies of the first kind, besides those already mentioned, are the lobed structure of the spleen and kidneys, the fissure of the vagina, of the womb, and of the bladder, &c.

Those of the second kind, are the different accidental solutions of continuity, as lacerations, wounds, a.nd fractures, which may depend on an infinity of causes ; the accidental union of parts originally separate, as in anchilosis, &c.

Â§ 38. We have already said that aberrations of form are sometimes congenital, and sometimes are not developed till after birth. But even if one of those anomalies exists when an infant is born, it does not thence follow, that it is original, that the altered organ has not been well formed at a former period, and that the monstrositj'- it presents does not result from a morbid cause acting upon it before birth. Nevertheless, irrefutable arguments unite to demonstrate, that congenital aberrations of the external form, are also usually original. We can refer these arguments to the following, which make us acquainted at the same time with the most essential and most remarkable conditions of original deviations of formation.

1 . The nature of the deformities announces that they are original. In fact,

a. Ã†ost of them can be explained in no other manner. Such, for instance, as the inversion of all the organs, or of some one only, the result of which is, that on the right side we see parts which are usually found on the left, and vice versa ; and much more, when the inversion takes place, not only in situation, but also in form ; the increase in the number of certain parts, as of the fingers and toes ; irregularities in the distribution and origin of the vessels, Â«&c. The attempts which have been made to account for these anomalies mechanically, are so monstrous, that they refute the hypothesis imagined to explain them. Organogenesis proves that many deviations of formation, are original ; since it can be demonstrated that they depend on the fact, that the organ has remained stationary at one of those degrees, through which, in its normal progress, it successively passes.

b. The sides of the body seem to differ a little, one from the other, in regard to the frequency of deviations of formation presented by them. In fact, most are found only on the left side. Thus, for instance, the vertebral artery rarely arises, except on the left side, from the arch of the aorta. We see, too, anomalies in the renal vessels of the left side, more commonly than in those of the right. To express this law more generally, we may say that the regions and the parts which are but imperfect representations of parts better developed, or to produce which, the formative power seems habitually to employ less energy, are also those which vary the most from the rules laid down, and which are formed with less constancy. Thus the sternum differs so much in respect to the number and size of its osseous nuclei, that we can scarcely establish any thing certain in regard to them, while anomalies in the vertebral column are very rare. So too, varieties in the vessels of the lungs, the most noble and most important organ, and which appears very early in the animal series, are less numei'ous and rarer than those of the renal vessels.

Nevertheless, this law has exceptions. Thus, for instance, the distribution of the vessels, varies more frequently in the upper than in the lower extremities, although the latter appear la^er than the former. But this exception is perhaps only imaginary, as the inferior members in the progress of life soon become larger than the superior.

c. Some systems are more subject to deviations of formation than others. The greater part of the nervous, osseous, and muscular systems, present anomalies more rarely than the other systems, particularly the vascular. Among the apparatuses, those of voice and respiration are less subject to derangement, than those of generation, digestion, and of the urinary passages. The last two, with the vascular system, are those which are most frequently anomalous. In this respect, there is a remarkable contrast in the nervous system between the brain, spinal marrow, and their nerves on one part, and the great sympathetic nerve on the other. The difference we have pointed out between the different organs certainly depends on this contrast, at least in part, since the organs which receive their nerves from the brain or the spinal marrow, are distinguished from the others, by the constancy of their forms. These organs in which the form is most constant are, at the. same time, more symmetrical, so that these two conditions seem to depend on the same principle. In fact, there is here only a simple difference of relation, since symmetry is to the individual, what constancy is to the species.

d. Anomalies of the same organ are similar. Thus, when two tongues exist, they are not placed side by side, but one above the other. Anomalies in the large vessels arising from the trunk of the aorta, vary much, in truth, but each resembles itself. Thus, for instance, if the right subclavian artery does not come from the arteiia innominata, it arises, most usually, above that of the artery of the left side, and there is not merely a division of the trunk of the innominata. When the vertebral artery forms a separate trunk, it is always the left which presents this irregularity, and itusually rises from between the large trunks of the left side, instead of implanting itself below the corresponding subclavian artery, although in the preceding anomaly, the origin of the right subclavian artery is placed lower even than that of the last. The perforation of the septum of the heart, the division of the urethra, the contraction of the stomach, always occur in one determined place.

e. In the anomalies of an organ there is a gradual transition from one to another. We can establish a series from the slightest anomalies of an organ, to the greatest disfigurement of the whole organism. Thus the doubling of the whole organism commences by the multiplication of the toes, the heart, the head, and is arrested when two bodies are united by the head, the chest, the abdomen, &c. So too, in monstrosities of an opposite character, there is a perfect gradation from the approach of the two eyes, to the existence of only one on the median line, with wlhch the anomalies attending it in other parts of the head, coincide. We can also trace this transition from the inversion of the inferior limbs, to the existence of a single pelvic member, which is also central, and developed very imperfectly. This law does not contradict the preceding ; it only restricts it to a certain extent, and the more, as the different degrees of the anomalies of the organs present themselves not merely once, but frequently exist in different individuals of the same and different species.

f The deviations of formation are hounded by certain limits. To whatever extent the form of ah organ, or of the whole organism, may be abnormal, it can always be recognized, even when the organism is deformed by several simultaneous deviations of formation. Thus the heart is never seen on the back, the lungs in the abdomen, the cranium between the lower extremities, &c. These organs then are never anomalous to such a degree, that heterogeneous parts should be blended in one mass ; for instance, the nerves with the vessels, the aorta with the esophagus, &c. This is one of the strongest arguments against the hypothesis, that monstrosities depend on mechanical influences.

g. Slight anomalies are much more frequent than large deviations, both as regards the relation of the volume of the parts, and the influence of the anomaly on the functions. The small branches and ramifications of the vessels vary much, while the large trunks are more constant. It is much more common to see the radial artery arise from the brachial artery in the region of the axilla, or the left vertebral artery coming directly from the trunk of the aorta, than to see the right subclavian artery arising below the left, or the aorta divided completely or incompletely into three trunks. The rarest anomalies in the circulatory system are those which a.llow a mixture of the pulmonary blood with that of the body, and those which affect the health ; as the perforation of the septum of the heart, the origin of the pulmonary artery from the aorta, of the aorta from the right ventricle, or of the pulmonary artery from the left ventricle. This law may be expressed in a general way by saying that an anomaly is more frequent the less the arrangement of the parts varies from the normal state ; but thus expressed this law is not correct ; for instance, the perforation of the sep4um of the heart is a normal formation during the first periods of fetal existence, and nevertheless it exists much more rarely than varieties in the distribution of vessels, which are never normal.

2. The relations which connect deviations of formation to other conditions not dependent on the misformed organs themselves, prove that the.se anomalies are original.

h. The simultaneous existence of several anomalies in the same organism. Although but one organ is usually abnormal, a circumstance which is connected with the preceding law, nevertheless we sometimes find in the same body many which vary from the normal formation. The anomalies then present sometimes the same and sometimes a different and even an opposite character. Thus, in certain cases all the imperfectly symmetrical organs are inverted : those of the right side are found on the left, and those of the left side on the right. Again, several systems are deformed by a defect of development : often, and in fact most usually, some parts are deficient, while others are immoderately developed. But we rarely or never find supernumerary 'Organs in a body where the general form is characterized by an excessive activity of the formative power ; for instance, a double-bodied monster has never more than five fingers and toes. Thus, generally speaking, the formative powers appear not to employ more energy upon one part unless at the expense of another ; and one part remains deficient only because another is too much developed.

i. The simultaneous existence of several misformed fetuses, or the coexistence of a monstrous fetus with one that is tvell formed. We sometimes meet with twins or triplets which present similar deviations of formation in the same organs, almost always ascribable to a defect of development ; and it is more common to find two or three together which are monstrous on account of some fault in their development, that is to say, in general by defect. A singular relation sometimes exists in this respect between one pregnancy and another ; a finger, for example, which is deficient in one child is found in excess in the next. This law is the same as the .preceding, but applies to other objects.

k. JMonstrosities of the same kind are hereditary in some families. This does not cease even by marriages with other families, although it sometimes disappears for several generations. The best known examples of this are those families with supernumerary fingers. But the hare-lip, fissure of the palate, hypospadias, &c., are equally hereditary. Sometimes a tendency to produce anomalies is transmitted rather than an anomaly, although usually the species of aberration is then the same. The predisposition does not often extend except to one generation ; nevertheless, we may ask if cases of this kind have been well observed, and if, when such a tendency is developed in one generation, it is not transmitted at least to the following generations, as certain diseases are developed sometimes under favorable circumstances, and have now become contagious.

l. The influence of sex. We may state as a principle that anomalies are more common in the female. This phenomenon seems to us to depend upon the eighth law, since the organization of the female results from the development being arrested at an inferior degree. Hence it follows also that deviations of formation absolutely opposite in their nature are more common in the female than in the male. Nevertheless certain organs may be exceptions to this rule. Thus, several anomalies of the heart(l) and of the bladder(2) are found more frequently in the male than in the female.

VI. jyiost deviations of formation are analogous to what is seen in animals. The organs of man do not present a single anomaly which is not similar to what is seen in animals. A whole book might be written on this subject, and exact observation would multiply to infinity the facts we could now mention in favor of this law. It is founded on another law, that the human fetus while developing passes through several formations, and that those monstrosities which are formed essentially by the development being arrested- in one or another of these formations, are the most common because they were normal in the first periods of its existence. Nevertheless we trace a resemblance with the organization of animals in certain anomahes which have never been normal, such as the inversion of the least symmetrical organs, and most of the varieties of the vessels. This law then can be expressed in general terms as follows : All the organisms have one ijrimitive fundamental type : hence one may be transformed into another.(3)

n. The spontaneoiis appearance of similar phenomena during life, which do not result from the effect of an external lesion. The alterations of texture and all new formations are usually developed spontaneously. Why, then, is it not probable, after this, and setting aside too the arguments hitherto adduced, that, by a stronger reason, congenital monstrosities are original, and do not depend on external influences? But it is a peculiar anomaly which favors this opinion. In several animals, especially in the class of birds, the female habits and female desires are so effaced by age, that, although the' genital organs remain the same, yet in these particulars the bird belongs to the male sex. It is true that at first sight these phenomena appear to oppose the doctrine of original monstrosities, as they show the possibility of a total change ; but in truth they favor it, as they combat the opinion which ascribes these monstrosities to the influence of mechanical causes. To us it does not seem very unlikely that some parts originally well formed in the first periods of life should afterwards assume of themselves an abnormal form ; that, for instance, some parts at first single should afterwards become double, instead of merel^^ acquiring an abnormal volume, since the inferior organisms, which the fetus so much resembles, have the power, not merely of enlarging, but of increasing the number of their parts, under the same circumstances which in the superior animals are at most attended only with an increase of volume.

(1) Schuler, De morbo cÅ“ruleo, Muhldorf, 1810, p. 29.

(2) See Duncan's paper On the malformation of the urinary organs, in the Edin. Med. and Surg. Jour., vol. i. p. 132.

(3) This law has been perfectly developed by J. P. St. Hilaire, who has endeavored to demonstrate that the organization of vertebrated animals may be referred to a uniform type, i. e. that the mater ials of all these are the same ; but they vary in size, forms, and uses, and form the organization according to the wants of the animal and the medium it inhabits. Although their forms and size change, their connections always remain the same, their relations are invariable. The same materials being given, and animated by a sum of life nearly uniform in each class, a greater development of one cannot take place unless one or more of the parts adjacent suffer. Such are the principles of the truly philosophical theory which J. P. St. Hilaire long â€¢ince brought forward (Philosophie anatomique, 1818) as the Theory of analogies.

Â§ 39 . Thus almost all the congenital deviations from the normal form are primitive, or at least do not result from mechanical causes.(l) The classification most convenient for their study is that which views them in their essence. In fact it is not impossible that the formative power when producing them differs only in degree from its normal state ; and this proposition, although at present unproved, is not at least unlikely. Monsters may then be classed according as they are anomalous in quantity or in quality. The first class comprehends, 1st, monsters by defect, {monstre, per defectum,) their essence is a want of energy(2) ; 2d, monsters by excess, {monstra per excessum.) which are characterized by an excess of formative power.(3) The second are divided into those which depend upon the union of the characters of both sexes in the same individual, or the hermaphrodites, {monstra androgyna){4:), and 2dly, those which cannot be referred to any of the preceding classes, {monstra per fabricam alienam.)

To the first class of the first section are refeiTed the defect, smallness, and too long continuance in the forms or proportions of early youth ; to the second, the plurality, excessive volume, and too rapid development. The objects of the second section are expressed generally by the definition itself. As to the classes o"f the first, it appears that, besides the first two conditions, which are common to all the organs, the same kind of anomaly presents as many differences in each organ as naturally occur in its normal form and development. Besides the differences relative to the frequency of the anomalies, which we have before mentioned, we may remark that we find more deviations in formation in those -organs which while developing pass through the greatest variety of forms ; because this circumstance increases the number of temporary forms in which they can stop. Perhaps there are organs peculiarly predisposed to one or another class of deviations of formation ; this would certainly seem to be the case : thus, for instance, the abnormal multiplication is observed particularly in the limbs, but seldom in the internal organs or in the trunk. We may establish then, as a general law, that an increase of the formative power is directed rather to the surface, and diminution inwardly. Nevertheless there is only a difference in degree, as nothing is rarer than monsters from defect of the external parts.

(1) J. F. St. Hilaire has settled this important proposition also, (Des monsiru ositÃ©s humaines, Paris, 1822.) Monsters have given new support to his doctrine of the unity of composition in vertebrated animals. In fact he has observed that these anomalies are usually marked by the excess or deficiency of only one of the parts which form the being in its proper state, but that the parts themselves are often equal in number, and their relations are always the same. Although these observations have been confined to monstrosities of the head, they are sufficient for us to conclude, by induction, that all others enter into this common law, and that their origin is truly dynamic and vital. F. T.

(2) We have given the complete history of these deformities in our Handbuch der pathologischen Anatomie.

(3) The general laws and particular conditions of these anomalies have been mentioned in our Cortimentarius de duplicitate monstrosÃ¢, Halle, 1815.

(4) Besides several treatises on hermaphrodites, some of which are excellent, as those of Ackermann and Burdach, consult the second volume of our Handbuch der pathologischen Anatomie.

Â§ 40. Mteralions of texture extend to all qualities connected with the intimate composition, that is to say, principally, 1, to the color; 2, the density ; 3, the number and the composition, of the particles which contribute to form the whole part ; and finally to the chemical composition.

Alterations in texture, considered generally, consist essentially in the formation of a tissue different either in one or in all parts from the normal tissue.

1 . The abnormal colors are very often? accidental and foreign to the tissue which presents them. This takes place when, as in jaundice, cyanopathia, &c., the color of this tissue anses solely from the morbid state of other organs, or when it is not situated in the tissue, but in the fluids it contains ; it then disappears as soon as the disease which caused it is cured. On the contrary, the color is rarely or even never normal when the tissue varies from the rule in another relation : in this case it is darker, brighter, or entirely different. Generally it becomes more clear when the morbid alteration is not caused essentially by an excessive development of the vessels.

2. The density is sometimes greater and sometimes less. In the first case, the organs are hard and firm, in the second, loose, soft, brittle, and fragile.

3. Usually the morbid tissue is less distinct and more uniform ; the number of vessels is often increased, and often also diminished, &c.

4. The chemical composition also varies much. Here applies all that has been said above with regard to its intimate texture.

We should observe in general that the texture of the organs changes in two different ways. Sometimes an organ whose conformation is regular is partially or wholly changed into an abnormal tissue. Sometimes a new and anomalous tissue is developed near it, entirely different from the old tissue, which disappears as the former mcreases. Nevertheless this difference is only apparent, for even in the latter case the new tissue is unlike that whose place it supplied, and is only the change of another, ordinarily of the mucous tissue, which has assumed an abnormal state.

The most general condition of the alterations of texture, and the most general cause of their production, is inflammation, which may be defined a state in which the blood flows in greater abundance towards a part of the economy, and attempts a new formation.

Even the alterations of texture are either the repetitions of a tissue which already exists in the normal state, or formations entirely abnormal, which do not exist in the regular state.

All the parts are not anomalously produced, nevertheless this is the case with almost all, and especially the most simple. Thus we see the cellular tissue abnormally produced, which then contains fluids of a different nature ; the tissue of the bones, and even enamel, that of the cartilages, the fibro-cartilages, the fibrous tissue, the skin, and several parts of the epidermoid tissue, especially the horny parts and the hairs ; the serous texture, which, like the cellular, contains different fluids, the synovial tissue and the mucous tissue.

As the vessels and nerves enter more or less evidently into the formation of several of these tissues, we may say they are reproduced in an abnormal manner, whether they do or do not arise from vessels and nerves previously existing.

The muscular and glandular tissues are those only which appear not to be formed anew.

These repetitions of the normal formations take place principally in two different circumstances ; sometimes to repair a loss of substance, and consequently at the place where the organ usually exists ; sometimes accidentally, and in other places. This difference is merely accidental : the proof is, that those parts which are easily and perfectly reproduced after having been destroyed, or those which grow more than once in the'normal state, are those also which are most completely and frequently developed as anomalies in other parts of the economy. Here are included the mucous tissue, the bones, the teeth, the hair, and especially the epidermoid tissue.

On the contrary, the muscular and the glandular tissues are never reproduced.

The most essential characters of the new formations of this kind, resemble those of the parts of which they are repetitions : their texture and chemical composition are the same ; they pass through the same periods of development, and exercise no injurious influence on the health and life mrless from their mechanical effects, or because they divert the formative power from other organs. The accidental differences found in parts which are produced abnormally, are a less perfect form, a chemical composition which is often not exactly the same, while their duration is shorter.

It is difficult to class the abnormal formations which are entirely new, because they differ only by insensible shades. Generally they have this in common, that at first, they are more solid than the organs in which they are developed, or which are changed to them, which destroys them and those organs ; and that in all those and particularly during the latter periods of their existence, they have a marked propensity to pervade the whole organism.

Â§ 41. XI. The organic form every where presents traces of a formation in accordance rvith the purpose to be attained. It is impossible not to perceive that an intellectual power, whatever may be its relations to matter, has governed the formation of the organized bodies. This is especially confirmed by those mechanical arrangements which we find in a multitude of places, and by the greater protection given to the organs essential to hfe. Among the phenomena of the first class, we shall mention the valves established in those vessels which have no immediate power of impulse, as the veins and the lymphatics, and the multiplicity of these valves, either at those points where the friction is greatest, as in the small veins and in the lymphatic vessels generally, or in those where there is no mechanical impulse, as in the lymphatic system. On the contrary, thereare no valves in those veins where the different trunks anastomose together. In other parts of the vascular system, also, as at the base of the aorta and pulmonary artery, between the ventricles and auricles, we find valves which oppose the reflux of the blood. A similar arrangement exists also when it is required to separate parts of the same cavity in which different functions are executed ; for instance, at the union of the stomach with the small intestine, and of the latter with the large intestine, &c.

As to the phenomena of the second kind, we see that the organs most essential to life, as the brain, spinal marrow, and lungs, are wholly or partially inclosed in large cavities, the skull, vertebral column, and the thorax, which are also particularly remarkable, on account of their circular form. So, likewise, the veins are situated less deeply than the arteries.

The duplication of most of the organs deserves also to be regarded in this point of view, since it allows the continuance of the function, even when an organ, or a portion of it, is destroyed. Sometimes the remaining organ increases in size, as happens, for instance, m the kidneys ; while, sometimes, the sound portion redoubles its activity, as in the brain, lungs, &c., although in fact one half can never be perfectly replaced by the other.

The texture and external form of all the organs seem to harmonize with the final end of the organism, since most anomalies soon suspend its functions.

Â§ 42. Each organ has its peculiar functions. Nevertheless, there are certain conditions, in respect to which the functions of some organs agree together better than in regard to certain others. On this is founded the classification of the functions. The first, and most general division is that which divides the organic actions into functions which are related with consciousness, with the spiritual existence, which connect mind and the external world, the animal functions properly so called, and into those which immediately concern the material existence, the preservation of the substance, which are accomplished without consciousness^ the vegetative functions. These functions unite and constitute, the first, the animal life, the second, the vegetative, organic, or automatic /ije, a division to which Buffon,(l) Grimaud,(2) and Bichat(3) have called the attention of physiologists. The latter has assigned to the two lives, and among other things to the forms of their organs, peculiar characters which have been adopted by modern writers,(4) and are reduced to the following ;

1. The organs of animal life are symmetrical, those of organic life oroiunsymmetrical. To the fii'st class are referred, 1, the brain and spinal marrow, with their nerves and appendages, or the nervous system of animal life ; 2, the muscular system ; 3, the osseous system ; and 4, the organs of voice. The second comprises, 1, the vascular system ; 2, the great sympathetic nerve ; 3, the digestive apparatus ; 4, the respiratory apparatus ; and 5, the urinary apparatus. This difference, as respects symmetry, is seen even in the anomahes, which appear on both sides at once in the first class, and exist on one only in the second.

(1) Histoire des Animaux, Paris, 1709, vol. ii. ch. I.

(2) Memoire sur Nutrition, St. Petersburg', 1789, p. 3.

(3) Bichat, On Life and Death.

(4) Sprengel. Itisi. Med. vol. i. p. 197, 199.

Lately, some have wished to establish between the different systems of the animal fife, differences founded upon the greater or less perfection of the symmetry, and still more recently, it is pretended that the osseous system exceeds all others in this respect.(l)

2. The organs of animal life are formed in a type more constant than those of vegetative life : hence anomalies are as frequent in the latter as they are rare in the former.

3. The influence between the form and the activity of the organs in the hoo lives, is entirely different. An anomaly in the form of an organ of animal life, instantly deranges its functions, while the most considerable aberrations in that of an organ of organic fife are not attended with bad consequences. The normal condition of both halves of the organs of animal fife is especially necessary in order to the regular performance of their functions ; for every derangement in one of them is followed immediately by an interruption in the whole function. On the contrary, one part of an organ of vegetative life may be diseased without incommoding the function, if the other portion supplies its place. And again the symmetry is such, that one half of an organ of animal fife may be diseased, while the other remains in a state of perfect health ; while the disease of one half of an organ of vegetative life deranges the functions of ui/roiÃ¯.

Although these characters are true to a certain extent, yet they are too general. It is true, and the remark has already been made, (Â§ 23,) that the organs of animal life are disposed more symmetrically and more constantly than those of vegetative life. But this difference is only in degree, and is not a direct contrast. Neither are the organs of animal fife entirely symmetrical, -and when we consider what has been before stated, the symmetry of the organs of organic fife seems stUl more perfect. This difference, too, has no general value, since comparative anatomy demonstrates that it is not observed in the great majority of animals, for, in most of them, the organs of organic fife are not less symmetrical than those of animal fife, although Bichat seems to admit the contrary. Besides, even in man, the genital system is disposed with, as much symmetry as any system of animal life, while that belongs only to vegetative fife. It is true that Bichat separates it from these organs, saying that it ' does not relate to the individual ; but he is mistaken, since the essence of the functions fulfilled by this system, corresponds perfectly to that of the other organs of vegetative fife. It is not true that the anomalies of the organs of animal life exist on both sides at once, and that those of organic fife are found on one side only. We have almost always found varieties in the distribution of the vessels of the upper extremities, of the kidneys, &c., on both sides at the same time, wlrile anomalies of the muscles and of the bones are frequently found only on one side. That the osseous system is more S 3 mimetrical than the other systems of animal life, is also false. The same system demonstrates, also, the too great generality of the proposition which states that the type of the formation is more constant in the organs of animal, than in those of vegetative life, since we meet varieties of form in the bones, as often at least, as in the vascular system. Finally, the greater frequency of anomalies in the organs of vegetative life depends on the greater number of stages through which they pass. When these stages are numerous, as in the osseous system, and especially in some of its parts, deviations from the normal form are also very frequent.

(1) Bartels, Physiologie, Freyburg', 1809, p. 21.

The third proposition, especially, is too general. All the truth it contains, is, that deviations in the form of organs afreet their functions, if these functions depend in any measure on mechanical arrangement. It is of no consequence whether the kidneys are lobed or not, united or separated ; whether the stomach or heart is on the right or the left side, &c.; but when the kidneys are too small, or when one kidney is deficient, when the ureters are obhterated, when the stomach is contracted in its centre, when the valves of the heart are deficient or adhere, when there is only one ventricle instead of .two, when the aorta arises from both of these cavities at once, &c., the derangements are certainly more important than when the brain is oblique, when one side of the skull possesses more wormian bones than usual, or when a muscle is attached to an unusual number of ribs.

This pretended difference is then without foundation, and both for this reason, and because that duplication has been confounded with symmetry, the propositions mentioned by Bichat in his third law absolutely contradict each other. The normal arrangement of two parts of an organ of animal life is necessary only when, by their structure and relations with external objects, they form a single organ, and when their external form is connected with their functions, as happens, for instance, in the organs of the, senses. When this is not the case, a deviation in formation of one of the portions has no bad effect, because it is replaced by that which is not mal formed. The disease of one half of an organ of vegetative life does not always affect the function of the whole. When one kidney is diseased, the other enlarges. It is true that the disease in a part of an organ of vegetative life affects the function of the rest, but only when the different organs are parts of one whole ; thus, a disease of the liver affects digestion, because the liver forms part of the digestive apparatus.

Â§ 43. So far in regard to the general conditions of the human form ; before we pass to the general description of the individual organic systems, let us attend to the general conditions of the chemical composition, and the actions of the human organism.

Â§ 44. The human body, like all other organized bodies, is composed of proximate and remote chemical elements, even as it contains proximate and remote elements of form.

Along the remote elements, there is no one which is peculiar to it ; all are met with in the general organism. It contains, on the contrary, some of the elements found in nature, hut not all.

The union of several remote elements produces the immediate elements which belong particularly to organisms. We find especially oxygen, hydrogen, carbon, azote, and phosphorus, in almost all the immediate elements. The predominance of one or another of these principles distinguishes the materials from each other, as that of azote and phosphorus characterizes the chemical composition of animals, and consequently of man. Some of the immediate elements are more generally diffused, and concur to form more of the solids and fluids than others which are found only in certain parts.

Those which exist most generally are albumen, fibrin, gelatin, a peculiar substance, mucus, which resembles gelatin very much, and was long confounded with it, fiat, and several salts, wlrich also occur in other than organized bodies. Fibrin, gelatin, and albumen, are only modifications of one and the same substance ; they may be converted into each other by art : so too the most varied forms may be Anally reduced to a certain number of simpler terms (Â§5).

The immediate elements w'hich every where exist are, with the exception of gelatin,(l) contained in the common nutritive fluid, the blood. The blood is composed of globules {cruor, globuli) and of a coagulable fluid ; the latter consists of serum and fibrin, the primitive elements of form.

The fat is a substance generally diffused, which does not enter into the composition of organs, but only envelopes them.

The immediate principles which are found only in certain parts are acids and salts, or other compounds, which appear principally in the secreted fluids, to which they impart their pecuhar characters.

These immediate principles concur in different proportions to form the different organs and the different fluids ; and even viewed chemically, they may be considered as the proximate elements of the organism.

All the organic combinations, with a very few exceptions, take place contrary to the usual laws of affinity ; hence sooner or later after death they form other compounds, which obey the laws of affinity, and which differ from those above-mentioned, principally because they contain fewer elements, because they are more simple.

Although the solids and fluids differ from each other by the excess of an immediate principle more or less properly belonging to them, and this peculiarity depends in its turn on the predominance of an immediate principle, still they may all be divided more or less easily into two classes, opposite to each other in this respect, that there is an excess of free acid in the first, and of free alkali in the second : a contrast which is also developed by electricity in the heterogeneous fluids. (2)

Q) Bostock, in Med. Chirurg. 'Prans. London, 1809, vol. i. â€” Marcet, ibid. vol. ii. â€” Berzelius, ibid. vol. iii.

(2) Besides the general works of Thomson and Thenard, we may consult on animal chemistry J. J. Berzelius, Foerelaesningar i Djtcrkemien, Stoclcholm, 1802-6,

Â§ 45. The organisms possess dead and living forces, which differ from each other inasmuch as the latter do not belong to them except for a certain period called life, during which only they may be considered as organisms enjoying a separate existence. Nevertheless these dead forces themselves differ very much during life and after death, for they depend on the form and chemical composition of the parts : so that the change death brings in this form and composition ought necessarily to produce other phenomena.

The living forces of the organisms may be referred to three, according to the different phenomena of action presented : 1 , productiveness, {productivitas) ; 2, motivity, {motilitas) ; 3, sensibility, {se7isilitas) .

All the phenomena arising from these forces can also be reduced to two classes, according to the principle which forms the basis ; these are the material and the intellectual ; for we observe that the substance changes in the phenomena of formation and motion ; but this is not seen in those of sensation.

The phenomena of formation essentially consist in the production of a peculiar substance, formed at the expense of another which is unlilce it. The formative power shows itself in preserving the normal state, or in bringing to it the abnoriSal state. If this abnormal state be so changed to the normal state that a new part forms in the place of that which has been destroyed, the phenomenon is called regeneration or reproduction {regeneratio, reproductio) ; so too the preservation of the normal state of the species by the formation of a new creature is called generation {generatio). The substance which produces all these new formations is the common nutritious fluid, the blood, which is itself formed from heterogeneous substances, in accordance with the same laws by which all organic products are derived from it. The quantity of nutritious fluid increases then in a local or general manner, in order that each new formation may taire place ; and this state may be genetically termed iiiflammation.

The essence of the phenomena of motion is an altetmate change in the degrees of cohesion and form, which increases the volume in one direction at the expense of the same volume in another direction. When a part endowed with this power contracts and shortens, it swells, and becomes thicker ; when it lengthens, it seems more and more thin. But in the first of these two states it is also much harder than in the second ; either from this circumstance, or because the first state is the immediate result of an irritation acting on the part, it is called the active state of the organ susceptible of motion. We are certain that, although the volume and the mass are the same in the two cases, nevertheless the nature of the two states is entirely different, even when the chemical composition of the part should not be modified, and the difference should consist only in a change of cohesion.

2 vols. â€” Id., Ucbcrbl.ick Ã¼ber die Zusammensetzung der thierischen FlÃ¼ssigkeiten, Nuremburg', 1814.â€” Id., Uebersicht der Fortschritte und des gegenwaertigen Zustandes der thierischen Chemie, Nuretnbvirg, 1815. â€” J. F. John, Chemische Tabellen des Thierreichs, Berlin, 1814.

This vital motivity ditfers much from similar dead forces, particularly from that of elasticity, although it is somewhat analogous to them. Neither should we confound it with the extensibility and the contractility of tissue admitted by Bichat, who represents them as principles of pecuhar phenomena, which are either phenomena of formation or merely those of elasticity.

The phenomena of motion have also been classed either from the manner in which this motion is manifested, or from the relation between it and the cause on which it depends. Thus they are distinguished into voluntary and involuntary motions, or into animal, which are considered as belonging to animals only, and into organic. The latter have also been divided into sensible and insensible. But if the first classification, founded on the relation of the phenomena to their remote causes, be correct, the second is not, since the insensible organic motivity depends only on the phenomena which become active probably in another manner.

Sensibility is the power of receiving and of propagating impressions. It belongs to the nervous system, which should be considered as the organ of the internal principle, or organ of the soul, since it is in one of those parts that the spiritual principle experiences, from the impressions received by its periphery, the spontaneous changes afterwards transmitted to other organs by the conducting portion of the system.

As all the nerves do not propagate the impressions they receive, even to that part of the nervous system in which the changes relative to the intellectual phenomena take place, or which immediately cause them ; and again as all the intellectual changes are not transmitted to the same organs, the sensibility may be distinguished into animal and organic ; and although this chiference relates only to the nerves, we may extend it to the organs themselves : so that some are organs of animal and others organs of organic sensibility. Nevertheless, we would ask, if to estabhsh this distinction too much latitude be not given to the idea of sensibility, or if that be not wrongly confounded with that of susceptibihty in general. Then the animal sensibÃ¼ity alone would be called sensibility, and those parts destitute of it would be called insensible. The phenomena alledged in support of the hypothesis of sensible or insensible organic sensibÃ¼ity, do not prove its reahty ; even as, on the other hand, those which they assure us demonstrate the presence of a pretended sensibility purely organic in certain parts, are not suificient to justify the admission of this hypothesis.

General Anatomy. Part II. Description Of The Individual Organic Systems

Â§ 46. We have already stated, (Â§ 15,) that the different systems composing the organism, are divided into general and particular. The general systems, the mucous, the vascular, and the nervous systems, exist in all parts of the economy, and everywhere unite to constitute the body; and form, more or less perceptibly, the basis of all the other systems. They differ, however, in their extent : that of the nervous system is much less than that of the vascular, and the latter cannot be demonstrated in many parts where the mucous tissue is evident. The mucous tissue, then, is the most general, anil, in fact, is the matrix of all the organs. It also is the first to appear. We ought, then, to mention it first.

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Reference

Meckel JF. Handbook of Pathological Anatomy (Handbuch der pathologischen Anatomie) Vol. 1. (1812) Leipzig.

Volume 1. Table of Contents

Cite this page: Hill, M.A. (2024, April 26) Embryology Meckel1812-1 Anatomy 1. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Meckel1812-1_Anatomy_1

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