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body is whitish and even transparent; the colour of the organs is developed only gradually. In the first period of their existence the systems are characterised by very great softness; it is only by degrees they assume the normal consistence. The traces of the primitive formation continue in some parts during the entire course of life; whilst, in others, no trace whatever can be discovered. According to Serres every organ is primarily formed of two lateral halves tending to unite on the median line. This is the law of centripetal formation. The liver commands in some degree all the evolutions observed in the viscera of the abdomen and chest. Placed in the middle of these two cavities, it is by it and around it that everything is arranged and disposed; its position assigns their position to the other viscera. The opinion, that the degrees of development which the human body passes through from its first origin to the moment of its perfect maturity, correspond to constant and permanent formations in the animal series, has now been proved to be false.

CELL THEORY.

The author next proceeds to examine into the way in which the elements of the different systems take their origin, grow, and become transformed, so as to constitute the different tissues of the human body. This branch of anatomical study is mainly indebted for its present state of comparative perfection to the microscope. The origin of the cells in plants— the manner in which these become transformed, so as to compose the different elementary parts, &c. become subjects of great attention—this circumstance tended considerably to facilitate the study of the development of the tissues of animals. Raspail was probably the first, who insisted on the identity of development in the vegetable and animal tissues, by establishing his spiro-vesicular theory. Everywhere, he says, a mothervesicle produces other internal vesicles, attached by the hilum and capable, in their turn, of becoming mother-vesicles. The vesicles become transformed, as in plants, into fibres, spines, &c.; the number, the position, &c. of the internal spirals, &c. produces the different organs. Dutrochet also insisted on the analogy existing between the development of the two organic kingdoms. In his first researches into histology, Valentin observed that the primordial mass of all the tissues was constituted by peculiar granules found in a transparent gelatine; he pointed out the difference of these granules in the serous and mucous structures at the period when these are being separated in the blastoderm. In the vascular system he found large globules or cells, which, from their form and aggregation, he compared to the cellular tissue of plants. He also called attention to the analogy in form between cartilage in a state of ossification, and the cellular tissue of plants. Valentin described the round cells of the globules and the intercellular substance placed between them in the chorda dorsalis of young embryos. Simultaneously with the zoologists, the botanists also directed their researches to the development of plants. J. Brown, in 1831, made mention of the nucleus of the cells of plants; Schleyden followed up these researches, and established a theory of which we here subjoin a resumé. In the gum of plants there appear at first some corpuscles, either mucous, or others somewhat larger, with more distinct contours. Around these

corpuscles there are formed granulations which, with the enclosed corpuscles, Schleyden has called cytoblasts. The cytoblasts enlarge; when they have attained their full size, there arises at one of their surfaces a very thin transparent vesicle: this is the young cell, which soon becomes more consistent and larger, so that the cytoblast appears in the form of a nucleus; this nucleus is subsequently absorbed. Immediately after the publication of Schleyden's works, Schwann applied himself to the study of the animal tissues: he completed the analogies resulting from the observations previously cited, by stating that the primordial gelatinous mass of the tissues consists in cells, and that the bodies found in them are nuclei. One sole principle of development, says Schwann, scil. the cellular formation, is the basis of all the organic tissues, however different they may be that is to say, Nature never collects the molecules immediately into a fibre, a tube, &c. but she always at first forms a round cell, and then transforms it, where it is necessary, into different elementary formations, such as we see in the adult state. The formation of the elementary cells is accomplished in all the tissues, with respect to the principal points, according to the same laws. The ulterior formation and the transformation of the cells are different in the different tissues.

The fundamental phenomenon of the formation of the cell is thus described at first there exists an amorphous substance, the cytoblastema, which is found in cells already existing or outside them. Generally, small spherical corpuscles, nucleoli, appear first in the cytoblastema: a substance of greater or less thickness and very finely granulated, is then precipitated; and including one or two of these corpuscles, it forms small round or oval masses, spherical or flattened; these are the nuclei of the cells. These nuclei are small opaque, granulated bodies, seldom smooth or transparent, being from too of a millimetre in diameter; they are solid or hollow in the latter case they are constituted of a thin, smooth, amorphous membrane, and their contents are limpid or finely granulated. Around these nuclei the cells form in the following manner: there is precipitated at the external surface of the nucleus a layer of a substance consisting of very fine granules, and different from the cytoblastema which surrounds it. This layer is not at first very distinct; but, by degrees, it undergoes changes by intus-susception, it becomes more distinct and more solid, and its external surface is changed into the membrane of the cell. This membrane at first surrounds the nucleus; but by little and little it becomes enlarged, and in the different cells there is developed a substance of a different chemical composition: the nucleus remains attached somewhere to the inner side of the membrane; but, at a later period, it generally disappears. The cytoblastema is deposited either outside, or within cells: the new primitive cells are formed, consequently, either in cells which already exist, or outside in the intercellular substance. With respect to the place where the new cells are formed in a tissue, the following is the law they always appear at the point where the nutritive liquid penetrates in the first place into the tissue. Hence the formation of new cells, in the unorganized tissues, can only take place at the points of contact with the organized substance; whilst, in the tissues completely organized, where the blood is distributed through the entire tissue, it may take place through their entire substance. Schwann distinguishes in the cells two sorts of

phenomena: the plastic and metabolic phenomena. The former are manifested by the formation of the cells in the cytoblastema; the latter, called forth by the metabolic forces, are the chemical transformations of the contents, produced by the solid parts of the cell, that is, by the nucleus and membrane. The way in which the cells become transformed into the elementary parts of the different tissues varies very much. The most important differences are the following:-1st, elongation of the cell into fibres, resulting probably from the circumstance that several points of cellular wall grow more strongly than the others; 2nd, the division of an elongated cell into several isolated fibrils; 3rd, the fusion of several simple or primary cells into a secondary cell. Schwann divides the tissues, according to the development of their elements, into five classes :-I. Individuality of the cells. 1st, isolated cells. a. In the liquids: globules of the blood, mucus, pus, and lymph. b. In the tissues: ganglionic corpuscles. 2nd, agglomerated cells: pigment, fat, horny tissue, crystalline. II. Fusion of the cells. 3rd, re-union of the membranes which belong to the cells; individuality of the cavities: cartilaginous, osseous, dental tissue. 4th. The cells become elongated and form fasciculi of cylindrical fibres cellular, fibrous, and elastic tissue. 5th. Complete fusion of the membranes and cavities which constitute the cells: muscles, nerves, capillary vessels. Valentin states moreover that, similar to that which takes place in the vegetable kingdom, there is seen in the animal kingdom a granulated nucleus, containing one or more corpuscles, surrounded by an envelope (cell) more or less independent; this latter consists in a separate wall, and distinct contents. All the tissues, however heterogeneous they may be in their state of perfect development, result from this fundamental formation. The different ways in which this development takes place, are referred to nine fundamental types. Their enumeration we shall here omit. So important and extensive is this cell-formation, that according to the observations of J. Müller, Henle, and Valentin, it presides also over all new pathological formations. It is proved that all their fibres arise from cellular fibres. The general primary form then of all the tissues is the cell, a product of the transformation of the nucleus, whose existence is preceded by that of the nucleolus. The young cells, that is, the cells in the early periods of their existence, are soluble in acetic acid, whilst the nuclei remain insoluble. The author here subjoins the results of Henle's observations regarding the metamorphoses of the nuclei, and concludes this part of his subject with some reflections on the cell-theory. This theory he shows to be founded by analogy on Schleyden's observations regarding the structure and development of plants, observations too far from being adopted by all botanists. However the truth of Schleyden's remarks would prove nothing in favour of this assumed identity in the structure of animals and vegetables. The author thinks that the advocates of the cell-theory have sometimes allowed their imagination to be carried away by certain appearances; the observations have been interpreted in a forced and arbitrary manner, whilst other facts have been passed over in silence which were found to be opposed to the ideas already taken up. There is not a granule, which, under the eyes of some observers, has not been transformed into a nucleus or nucleolus; at other times, globules of fat have been taken for cells, with the nucleus absorbed. He next ex

amines the principles on which the cell-theory is based. To the question, whether the microscopical elements of the animal tissues are cells, he answers in the negative. The term cell should be applied only to elementary parts which admit a clear distinction between parietes and contents. Now this occurs very rarely in the animal tissues. In most instances we meet lamellæ or solid corpuscles penetrated with an organic liquid. This liquid is not collected in an empty space within the corpuscle, since no such space exists, but it penetrates equally all its organic woof. So that the name of cell is inapplicable to most of the elementary parts.

The most general process by which the elementary parts become developed are, according to the author, as follows: The liquor sanguinis (le liquide sanguin) transuding through the parietes of the vessels, occasions the coagulation of the fibrine dissolved in this plasma. The fibrin is coagulated in the form of small corpuscles, to be hereafter described under the name of fibrinous globules. These corpuscles become the centre of a new formation; a solid matter is thrown down gradually around these corpuscles, which in this way become surrounded by a solid substance different from that of the fibrinous globule. This matter proceeds from the coagulation of the blastema or primary organizing matter. Attraction takes place chiefly in two directions, in length and breadth; the thickness is inconsiderable. In this manner the primary corpuscle, the fibrinous globule, is transformed into a new element, two dimensions of which have greatly the advantage over the third. This form is so much the more remarkable, as the same law is also observed in the dimensions of the entire body. The new elements are either lamellæ or corpuscles; they present the primitive corpuscle lodged in their substance, sometimes on their surface. From its position we shall call the latter the nucleus of the lamella or corpuscle. This nucleus may still enlarge after the formation of the lamella. It was stated that the primary corpuscle, the nucleus, in the theory of cells, arises from the coagulation of the transuded liquor sanguinis. But we may admit that a similar coagulation may also take place in the midst of the blastema: the corpuscle, produced from this coagulation, would in its turn become a centre of new attraction. The attraction around the primitive corpuscle cannot surpass certain limits, and the matter thrown down becomes more and more consolidated, and shortly becomes quite distinct from the blastema in which it is plunged. In some cases the external surface is better consolidated, than the rest of the corpuscle, and in this way occasions the production of an external membrane; this membrane, however, is only of subsequent formation, and frequently cannot be clearly distinguished from the entire element. An example of this formation presents itself on studying the texture of the grey substance of the nervous system. It will be seen that the grey corpuscles exist at first, that the grey matter is precipitated around these corpuscles, that it gradually becomes solidified, and that in some cases there is even formed an external membrane. The process of the formation of the ovum appears analogous. At the same time, or before the matter is precipitated around the corpuscle, changes occur in its interior which give rise to that which the abettors of the cell-theory have called the nucleolus. These elements appear to us then to be the result of a secondary formation. In some cases the matter precipitated around the primitive

corpuscle, forms concentric layers; at other times, this corpuscle remains excentric, that is, the matter precipitated rises over the corpuscle, like the glass of a watch.

The author next makes some remarks on the increase and decrease of the organic parts, on the regeneration of tissues which may have been destroyed, and on the differences subsisting between man and other animals, between one man and another, and also the differences observable in the same man at different periods of life, and then proceeds to consider the results of what has been said with respect to physiology and pathology.

The facts acquired to science by the researches of general anatomy find their application in the examination of the physiological and pathological phenomena of the human body. The explanation of these phenomena rests partly on the facts made known by general anatomy. The study of the physical, vital, chemical and anatomical characters will frequently afford an opportunity of speaking of the results acquired to physiology and pathology. The most important result of these researches is no doubt the knowledge of the organic systems, a knowledge which explains why parts very remote from each other are simultaneously affected. The attention of medical men to these circumstances was first called by Pinel. It was these ideas that formed no doubt the first basis of modern medicine, and of the researches of Bichat.

ANOMALIES.

The congenital deviations from the normal type sometimes seen in the body, either in its external forms, or in the distribution of the organic systems, present very great differences. When the anomaly exercises no influence on the performance of the functions of the organ which is its seat, and that it does not at all modify the external form of the body, it is called anatomical variety. Such, for instance, is the presence of a supernumerary muscle-the existence of only one kidney-transposition of the viscera, &c. When the congenital deviation opposes the free discharge of the functions, so as to render the existence of the individual impossible, it constitutes a monstrosity properly so called. The etiology of anomalies is derived from our knowledge of the development of the organic systems. The opinions which have been advanced in accounting for monstrosities may be referred to three principal hypotheses, which mutually support each other: these are the theory of arrest of development, to which is closely allied that of centripetal formation, and the opinion which attributes a creative power to the arterial system. According to the best anatomists and physiologists most anomalies depend on arrest of development monsters, in their conformation, represent, by one or more of their organs, the transitory state of the embryo in its different periods of growth. M. Serres it was who laid down the law of centripetal formation. On this supposition every organ is primarily formed of two lateral halves, tending to unite on the median line. G. Saint-Hilaire applied this law to explain monstrosities. If the development is arrested, the union does not take place hence we have median scissures. The development, on the contrary, being in excess, the organs then tend to unite on the median

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