ART. VII. 1. Die Selbständigkeit des sympathischen Nervensystem durch anutomische Untersuchungen nachgewiesen. Von F. H. BIDDER und A. W. VOLKMANN, Professoren in Dorpat. Nebst drei Kupfertafeln.-Leipzig, 1842. 4to, pp. 88. The Independence of the Sympathetic Nervous System, demonstrated by Anatomical Researches. By F. H. BIDDER and A. W. VOLKMANN, Professors at Dorpat. With Three copperplates.-Leipsic, 1842. 2. Untersuchungen über den Bau den Nervensystems. Von Dr. B. STILLING und Dr. J. WALLACH. Erstes Heft, enthaltend Untersuchungen über die Textur des Rückenmarks. Mit Abbildungen.Leipzig, 1842. 4to, pp. 52. Zweites Heft, enthaltend Untersuchungen über die Textur und Function der Medulla Oblongata. Mit 7 Tafeln Abbildungen.-Erlangen, 1843. 4to, pp. 72. Researches into the Structure of the Nervous System.. By Dr. B. STILLING und Dr. J. WALLACH. Part I-Researches into the Texture of the Spinal Cord. 1842. Two Plates. Part II-Researches into the Structure and Function of the Medulla Oblongata. 1843. 7 Plates. 3. Traités et Découvertes sur la Physiologie de la Möelle Epinière. Par J. VAN DEEN, Docteur en Médecine, &c. &c. Traduits du Hollandais, augmentés de nouvelles Recherches, &c.-Leide, 1841. 8vo, pp. 224. Treatises and Discoveries on the Physiology of the Spinal Cord. By Inquiries into the Functions of the Spinal Cord and Nerves. By Dr. 6. Die Physiologie des Rückenmarks mit Berücksichtigung seiner pathologischen Zustände für pratische Aertze. Von BENEDICT SCHULTZ, Doctor der Medicin.- Wien, 1842. 12mo, pp. 70. The Physiology of the Spinal Cord, with reference to its Pathological States, &c. By Dr. B. SCHULTZ.-Vienna, 1842. Ved ADOLPH 7. Mikroskopiske Undersögelser af Nervesystemet. 8. Untersuchungen über die Physiologie der Nervenfaser. Von Dr. GEORG HERMANN MEYER, Privatdozenten zu Tubingen, &c. Tubingen, 1843. 8vo, pp. 316. Inquiries into the Physiology of Nervous Fibrils. By Dr. G. H. MEYER, Private Teacher at the University of Tubingen.-Tubingen. THE anatomy and physiology of the nervous system constitute a continually widening field of research to the physician, and it is matter for satisfaction that the cultivators become more numerous as its boundaries enlarge. It would be scarcely possible to estimate this branch of medical science too highly. Practical medicine in all its branches will be efficient in proportion as our neurological knowledge becomes more accurate and extended, but especially in those departments which comprise the diseases of the brain and nerves. General hygiene will draw largely also upon neurology for first principles; the laws regarding insane men must be based upon it; and mental philosophy or metaphysics must henceforth be cultivated as a portion of the physiology of the nervous system. These remarks will suffice as an apology, if one be needed, for presenting so long a list of works on the subject to the notice of our readers. 1. ELEMENTARY ANATOMY OF THE SYMPATHETIC SYSTEM. It is not yet decided by anatomists and physiologists whether the sympathetic be an independent system of nerves, or dependent on the cerebro-spinal system. In our review of Valentin's Four Books on the Functions of the Cerebral Nerves and the Sympathetic,' we expressed ourselves as coinciding in opinion rather with Müller and Remak, who maintain the former, than with Valentin, who holds to the latter. The anatomical researches of Professors Bidder and Volkmann were instituted with the express purpose of deciding the question; with what result is sufficiently indicated by the title of their publication. The two anatomists entered on their undertaking with a full knowledge of the points to be ascertained, and with a thorough conviction of the difficulties to be overcome. They knew that unwearied industry, unflinching perseverance, and the utmost caution against errors, were necessary to a successful result; and, in accordance with these views, they have, at least in one animal (the frog), traced the whole sympathetic, twig by twig, fibril by fibril, and had so accustomed their eyes to these microscopic researches, that when a good preparation of the nervous system of a frog was submitted to their inspection, they could say, at a glance, whether it was derived from the sympathetic or cerebro-spinal system; whether from a motor or sensitive twig; or whether from the root or trunk of a nerve: nay, they could even decide from this simple inspection, if the preparation were a portion of a spinal nerve, whether it was taken from above or below the point of junction of the nerve with the sympathetic branch, or far from it or near it; and if this point of junction itself were placed under the microscope, they could say whether it belonged to the three upper, the three middle, or the three lower spinal nerves. Having so thoroughly qualified themselves for microscopic researches, they claim the confidence of their readers as to the accuracy of the researches themselves. The first division of the essay is a view of the elementary composition of the sympathetic and cerebro-spinal system. The distinctive characteristics of the sympathetic ganglia were too striking to remain unnoticed by anatomists; as regards these they were agreed; but the relation of these ganglia to each other, to the nervous fibrils issuing from them, and to the cerebro-spinal system, gave rise to considerable differences of opinion. On the one hand, it was thought that the ganglia were like • British and Foreign Medical Review, vol. XI, pp. 299-300. little brains, and originated from fibrils; on the other that they were plexuses only, and that the fibrils entering them passed through them unchanged. Ehrenberg considered the microscopic characteristics of a sympathetic fibril to consist in a varicose structure, resembling strung pearls, and in a definite thickness of the primitive fibrils. This was to a certain extent a microscopic illusion; he discovered, however, the ganglionic globules. Treviranus did not confirm these researches, except that he found the primitive fibrils of the sympathetic were three or four times smaller than those of the cerebro-spinal nerves. He found, too, that the cylinder of which they were composed contained a softer matter than that of the cerebro-spinal nerves, and that the space observed between the contained matter and the outer membrane of the cylinder of the latter was wanting in the former. According to Valentin's researches, the ganglionic globules discovered by Ehrenberg are peculiar to the fibrils of the sympathetic ganglia and nerves, giving them their distinctive colour by being interspersed among them-the fibrils themselves being white. Valentin maintained also that there was no real difference between the two great classes of nerves. The views of Remak are already, doubtless, well known to all of our physiological readers through Dr. Baly's translation of Müller's Physiology and our own analysis of them, vol. VII. Remak terms the sympathetic the system of organic nerves, and adopts Valentin's views respecting the presence of globules or small oval knots, which closely resemble the ganglionic globules, but they are on the fibrils, not among them. The colour also of the fibrils is not dependent upon these bodies, but upon the peculiar organic structure of the fibrils themselves. Hence Remak added the term gray to organic as a synonyme, and consequently described the sympathetic as the gray or organic nerves. Müller and Schwann adopted Remak's views, Valentin, on the contrary, stoutly opposed them. maintained that the elementary structures described by Remak were only the membrane of the ganglionic globules, prolonged over the efferent fibrils, and that their softness and gray colour were caused by these membranes. The knots on the fibrils described by Remak are, according to Valentin, partly dependent on the remains of cells of the fibril-like epithelium, and partly an optical delusion. He insisted, too, that Remak had mistaken fibrils for cellular tissue. Henlè then entered the controversy in favour of Remak, acknowledging, however, that the latter had confounded various structures as epithelium, vessels, &c., with nervous fibrils. At a later period, Henlè repeated this acknowledgment more distinctly. Purkinje and Rosensthal next joined Valentin against Remak, but maintained that what Valentin called fibril-like beaded epithelium, ought properly to be termed the formatio granulosa, an elementary formation, having no special relation to nervous structures; and that the globules of which it consists by no means indicated the presence of organic fibrils. They insisted, however, against Valentin, that the latter really exist, and are characterized by a yellowish appearance, by their less size, their softness, and the want of double walls, and by their smoothness and but slightly granular surface. One of the inferences from their researches was that the cerebro-spinal nerves of the fœtus were not different from the permanent sympathetic nerves of the adult, and that the latter should be considered as a lower grade of development of the former. Pappenheim followed Purkinje and Rosenthal in the controversy, with whom he agreed as to the nature of the supposed ganglionic globules of Remak, and as to the similarity of the two classes of nerves in the fetal stage of development. He allowed also the existence of organic fibrils, and with Purkinje stated that they might be known from cerebro-spinal fibrils by their magnitude, contexture, and behaviour to acetic acid; and he agreed with Valentin as to the relation between the ganglionic fibrils and the nervous twigs. Pappenheim also found that a cerebro-spinal nerve never contained organic fibrils, unless when these were derived from the sympathetic nerves or ganglia, and that the branches connecting the latter with the spinal cord might be traced into the roots of the spinal nerve. Valentin, however, was not induced to change his own opinions, but maintained them the more strongly; and so our two professors step in to decide the important questions raised during the controversy, and (if that were possible) to end the strife. We shall now proceed to present our readers with an analysis of the results of their researches. As regards the colour and softness of the sympathetic nerve. According to Bidder and Volkmann, the colour is neither dependent upon interspersed globules, nor upon the sheaths of the fibril, but is sui generis, and dependent upon the fibrils themselves. The nerves are softer than those of the cerebro-spinal system, because the tendinous fibres in the sheath of the latter are wanting. As regards the elementary structure, our authors agree with Valentin, Henlè, Purkinje, Rosenthal, and Pappenheim in denying the existence of Remak's organic fibrils; they are opposed to all analogy; they are only found in the nerves of the two lower classes of vertebrata, and are wanting altogether in the sympathetic nerves of the warm-blooded; they are observed as inclosing blood-vessels around which numerous twigs are distributed; they are exactly like certain described forms of cellular tissue, particularly of embryonic life, and, in short, they are cellular tissue. On the other hand, our authors show that the organic fibrils described by Purkinje, Rosenthal, and Pappenheim are truly described, and are not identical with those described by Remak, and that the researches directed by Valentin against Remak's views are not applicable to those of the last-mentioned microscopic anatomists. Valentin is in error respecting the true nature of the sympathetic fibrils as much as Remak. According to Bidder and Volkmann, the fibrils of the sympathetic do not exhibit under the microscope the two dark textures peculiar to those of the cerebro-spinal system. They are, indeed, included within distinct boundary-lines (grenzlinien), but these are much less dark and broad. In this respect they have a remarkable resemblance to the cerebro-spinal fibrils in the embryo. In embryo calves, from two to three inches long, Bidder and Volkmann could detect no difference between them, even with the best microscope. Towards the end of the embryonic period, the sympathetic is little altered, but the cerebro-spinal fibrils are very similar to those of the sympathetic in the adult. Bidder and Volkmann infer from observations of this kind, that the difference between the two classes of nerves is not so great as to demand their appropriation to distinct tissues. According to observers generally, the primitive sympathetic fibril appears not as a hollow but as a solid cylinder, without the double membranous tube peculiar to the cerebro-spinal nerves. This view is confirmed by our authors. There are cases, however, in which these distinctive marks fail. In the perfectly fresh condition-that is, immediately after death-the fibrils of a cerebro-spinal nerve appear as perfectly transparent solid cylinders, with simple sharply-defined outlines (conturen), and it is only later that the two parallel lines are observed, giving the appearance of the double membranes. Occasionally this condition is observed in sympathetic fibrils. Acetic acid coagulates the contained matter of the latter, leaving the cerebro-spinal fibrils untouched; but this is a doubtful mode of distinguishing the two, and has probably given rise to numerous errors. Other uncertain characteristics are mentioned: that, however, on which Bidder and Volkmann rely is the admeasurement of the fibrils. The fibrils of both classes of nerves vary much in magnitude, as is shown by a table in which the diameter of various nerves from man, the cat, the calf, hen, frog, and pike is given. The largest fibrils of the sympathetic are, however, much smaller than the smallest. of the cerebro-spinal. Part of this table we give. The figures intimate fractions of the Parisian inch the nerve examined was the anterior root of a spinal nerve. The most usual size was the medium of the two measurements. The greatest variation is observed in the cerebro-spinal nerves. In frogs the smallest observed diameter of a sympathetic fibril was 0.00014 inch, the largest 0.00022 inch; while in the cerebro-spinal system, the two extremes were respectively 0.00022 and 0.00070. In the pike the extreme in the latter is still greater, namely, 0.00024 and 0·000132. The second division of Bidder and Volkmann's treatise is devoted to a consideration of the connexions between the sympathetic and spinal nerves. In a previous essay,* Volkmann had stated, after having examined all the anastomoses of the cerebro-spinal and sympathetic, that although for the most part the sympathetic fibrils in the cerebro-spinal nerves took their course both to the centre and circumference, yet it was evident that in many places the communicating branches were exclusively peripheral. He stated also that the fibrils of a communicating branch entering the spinal cord were divided into two sets, the one turning towards the head, the other towards the pelvis. In the frog the anterior roots of all the spinal nerves communicate with the sympathetic. The first, or hypoglossal, seemed to Volkmann, indeed, to be an exception : but more accurate researches have removed all doubts. The communicating branch is scarcely distinguishable by the naked eye, and in one instance contained only two fibrils. After joining the nerve the greater portion of the fibres go to the centre, the lesser to the periphery. The • Ueber die Faserung der Rückenmarkes und des sympathischen Nerven in Rana esculenta. Müller's Archives, 1838, p. 274. |