PART FOURTH.

Chronicle of Medical Science.

HALF-YEARLY REPORT ON MICROLOGY.

By JOHN W. OGLE, M.D., F.R.C.P.

Assistant Physician to St. George's Hospital, and Honorary Secretary to the Pathological Society.

PART I-PHYSIOLOGICAL MICROLOGY.

NERVOUS SYSTEM AND ORGANS OF SENSE.

Minute Anatomy of the Nervous System.-M. Jacubowitsch,* a Russian observer, has lately communicated to the French Academy of Sciences the results of four years' incessant labour and microscopical investigation into this subject. He has arrived at the following conclusions:

1. He found that all the cerebro-spinal nervous system, speaking generally, consisted of three kinds of nervous elements, i.e., cells of movement, cells of sensibility, and ganglionic cells, to which should be added the axis cylinders of all the cells. He determines that the ganglionic nervous system essentially appertains to the cerebro-spinal one. He also found that cellular tissue is an important element in the formation of the nervous system, not only uniting the separate nervous elements in the form of groups forming different subdivisions, but subserving nutrition by acting as the seat of the blood-vessels. Perhaps it may aid the function of the axis cylinders by the envelope which it affords them.

2. He determined that the medulla oblongata is to be considered as simply a continuation of the spinal cord, with an extensive development of the posterior horns, and the cells of sensation and ganglionic cells, the latter being generally situated in the neighbourhood of the central canal, and the termination of the fourth ventricle.

3. That the corpora quadrigemina form a direct continuation of the spinal marrow, with which they are united by the medulla oblongata. This is the furthest part at which all the nervous elements exist together in their special relationship, whether among each other, or as regards the origin of nerves.

These bodies are distinguished by the great horse-shoe commissure, in which the first kind of ganglionic cell is only found exceptionally, and which sends numerous fibres into the optic thalami and corpora striata. Hence this commissure is an essential means of union between the spinal cord and the medulla oblongata on the one hand, and the brain and cerebellum on the other.

4. That the cerebellum is to be looked upon as formed-(a) By a part of the anterior column and anterior horns of the spinal cord, which penetrate for the most part into the peduncle of the spinal cord towards the cerebellum, with their cells of motion and branches of nervous fibres. (b) By a part of the posterior nervous columns and their elements (cells of sensation), which

* Comptes Rendus, p. 290. Aug. 1857.

exist in the restiform bodies. (c) By ganglionic cells which, grouped in masses along with the above-named elements, form the mass of the medullary or white substance. This is placed in relation to the pons Varolii and corpora quadrigemina by the peduncles of the spinal cord towards the cerebellum, and the peduncles of the corpora quadrigemina. (d) By a grey substance forming the enveloping layer of the cerebellum, and remarkable for its pear-like cells.

5. That the hemispheres consist essentially of cells of sensation, with a peripheric layer formed, as in the cerebellum, by ramifications of axis cylinders terminating in a system of rods.

6. That the substance' of Rolando consists of axis cylinders, with or without medullary substance, existing not only in the posterior horns of the spinal cord but also in the brain, cerebellum, and corpora quadrigemina, with their fibrous network and their apparent layer of granules, which, in reality, are rings with simple or double contours, sections of nervous fibres.

7. That the corpuscles of the connective tissue cannot absolutely be determined. The cellular network appears almost everywhere in the form of very fine grains, and in certain places appears as a distinct network. Near the central canal, as also about the level of the aquæduct of Sylvius, and especially where the vessels are crowded, it assumes a filamentous form. Where the axis cylinders are bound together, it is changed into a homogeneous transparent membrane, with fine, almost immeasurably small granules.

S. That all the nervous elements unite with each other in three different ways. (a) By commissures, which place two groups, situated symmetrically, in relation, by means of axis cylinders. (6) By unions between the nervous cells of the same kind, near to or distant from each other on the same side. (c) By the layer at the periphery of the brain and cerebellum (the conche en baguettes), in which we find the three kinds of cells with their ramifications.

9. That the absolute and relative size of the three nervous elements forms the true criterion of the importance of the whole or parts of the nervous system. In man they are absolutely and relatively the smallest, and therefore in him they are most numerous. As these cells seem to multiply like other histological elements, it is probable that a numerical increase of nervous elements takes place at the same time as the diminution of part of the connective tissue during intellectual development, and this without the entire mass becoming larger. In like manner it has been shown that in dementia and different forms of cretinism the development of nervous elements remains stationary, or even that a substitution of connective tissue for nervous cells takes place. The various shades of colour seen in various parts of healthy brains seems only to depend upon the number, thickness, and other peculiarities of blood-vessels.

10. That all cerebro-spinal nerves are of a mixed character. The anterior and motor roots consist of filaments which pass from cells of motion and sensation, and ganglionic cells; and the number of these elements varies in the different regions of the spinal cord. The posterior roots, consisting chiefly of filaments from the ganglionic cells and those of sensation, contain some, also, from motor cells, whilst the nerves from the medulla oblongata consist throughout of filaments from the ganglionic and sensory cells only; a few only, namely, those taking origin from the course of the spinal cord within the medulla oblongata, having filaments from the cells of motion. All the cerebral nerves, excepting those of the three special senses, which consist only of filaments from the ganglionic cells and those of sensation, are formed by filaments from all the three varieties of cells. The varying thickness of the spinal cord, and the increased size of the medulla oblongata, depend upon the number and disposition of the nervous elements.

11. That in poisoning animals by conein, nicotine, prussic acid, &c., the nervous and cellular elements become destroyed, the membranes torn, the axis

cylinders separated from the cells and otherwise injured, and the contents of the cells hardened and dwindled, apparently from sudden interruption of their nutrition. This fact renders it impossible to trust preparations made from animals so killed.

OSSEOUS AND CARTILAGINOUS SYSTEM.

Articulation between the Cartilage and the Bone of the First Rib.-Professor Luschka has observed this on both sides of the body of a man aged fifty-five, of strong muscular conformation. On both sides the cartilage of the first rib had undergone complete ossification, and between the cartilage and bone only a slight movement existed, but still there were the true characteristics of an articulation—a cavity, cartilaginous investment of the opposed bony parts, and a fibrous enveloping material. The cartilaginous plates of the articular cavity had no smooth surface, but were uneven and occupied by fibrous villous projections, and consisted of a fibrous basis with cartilage cells intermixed. There was no trace of any synovial membrane or vessel holding cells. Luschka looked upon the formation as a joint arrested in development.

MUSCULAR SYSTEM.

Histology of Muscular Fibre.-Dr. H. Welckert considers that Leydig's view, according to which the small puncta or ringlets seen on transverse section of the primitive muscular bundles, are not sections of solid fibre, but of hollow spaces with sacculated margins, is owing to a confusion between fibrils and the so-called muscular hollow spaces. Having dried the muscles of a frog, and made transverse sections, which he moistened, he saw inside the contours of the pouches of the sarcolemma innumerable fine puncta, belonging to a deeply extending structure. The superficial end did not appear to be a ringlet, but a dark spot, which, on adjusting the focus, became glistening. Consequently the author looks upon the fibrils as being solid. But between the puncta, he noticed fissure-shaped cavities, which had a reddish yellow look on focussing and by direct light, and had a silvery appearance. These are to be considered as muscular hollow spaces, or possessing walls, as muscular corpuscles; and, according to the strength of the bundles, from four to twenty-four, could be counted inside a sectional plain. There are also elongated air-containing spaces, which in the case of fresh muscle, treated by acetic acid, appear as the well-known nuclei. The fibrils and muscular hollow spaces or corpuscles have been confounded by Leydig, according to Welcker, although they differ in size, form, and number. He considers, moreover, that these hollow spaces form a contrivance for the saturation of the primitive bundles, inasmuch as the capillaries only encircle these bundles. He could, however, not find any processes establishing a communication between these spaces, and therefore imagines them to be formed of cells, which, being analogous to cartilage corpuscles, he calls muscular corpuscles. They are somewhat smaller than the bone corpuscles. The author goes on to speak of the connexion between these corpuscles by fine processes, the whole forming an abundant system of fluidconducting spaces.

Muscular Fibres of the Tongue in the Frog.-Speaking of these fibres, Billroth states that the divisions of the primitive fibres diminish gradually in size, but yet often retain their transverse striæ, until close beneath the papillæ. Here, if not sooner, they are reduced to very fine dark fibres, which pass into Schmidt's Jahrbücher, No. 11, p. 154. 1857.

† Henle und Pfeuffer's Zeitschrift, b. F. viii. p. 225: as quoted in Schmidt's Jahrbücher No. 10, Band 96, p. 5.

: Deutsche Klinik, 21; 1857: quoted from Schmidt's Jahrbücher,

the processes of cells, with large nuclei, and contain lateral anastomosing branches. These branches in part proceed as fibrils into the papillæ, and are thus in connexion with the epithelial cells, which are found to possess cilia, and also short as well as long processes, by which they are in immediate connexion with the fibrils of the papillæ.

FIBROUS TISSUES.

Elastic Fibres.-Welcker, of Giessen,* after making observations upon the solidity of embryonal and the completely developed elastic fibres, determines that the complete form is not hollow. Even the finest elastic fibres, which are everywhere distributed in areolar tissue, and exist in the cutis and serous membrane, &c., are not hollow, inasmuch as elastic fibres filled with serum would exhibit an inner parietal contour if placed in water, which is not to be seen in them. The invisibility of the inner parietal contour could only be explained by supposing extreme thinness of the wall. But the excessive lustre of the elastic fibres exhibited on focussing, rather militates against the supposition of its hollowness, because if it was truly hollow, this glistering could only take place when it was filled with fluid which, like Canada balsam, had highly refracting powers, and such as is not known to exist in the animal body. The formative cells of elastic tissue show in water, on the contrary, no excessive lustre, and their contents are not more refractive than water itself. Consequently, Welcker concludes that elastic fibre is not hollow in an early stage of development, when the cell corpuscles are still in existence.

GENITO-URINARY SYSTEM.

Minute Anatomy of the Kidney.-Dr. C. E. Isaacs, in a very long and well illustrated article, after passing in review with criticism the opinions of most of those who have written on the anatomy and physiology of the kidneys, such as Malpighi, Bellini, Bowman, Johnson, Gerlach, and others, gives the results of his own observations. He applies himself to the elucidation of the following points-The nature of the tubular epithelium; the connexion between the Malpighian bodies and the uriniferous tubes; the existence of ciliated epithe lium in the tubes of the higher animals, and of nucleated cells on the Malpighian tufts; the presence of a fibrous matrix, and the arrangement of the venous plexus.

The author considers that the discrepancies which exist in the statements of so many writers on this subject, arise from their employing different and insufficient methods of observation; and states, that besides injections, to which many have confined themselves, his own observations were conducted upon preparations rendered transparent by certain processes, which also permitted their being examined as opaque objects.

Speaking of the tubes and their epithelium, he describes the latter as of the tesselated kind, according with Hassal, and differing from Bowman and Johnson, who describe it as spheroidal. He believes that when the epithelium possesses the form last mentioned, it is owing to the kidney not being fresh or being diseased, or that the epithelium has been altered by some mode of examination. As regards the presence of ciliated epithelium in the tubes, which is well known to exist in many animals, the author concludes that ciliary motion exists in the uriniferous tubes of animals of a high grade, but in an imperfect and rudimentary condition. Yet although he had seen movements connected with the lining cells, he had only once seen a single cell apparently fringed with cilia, and that was in the ox.

Henle und Pfeuffer's Zeitschrift, viii. p. 225: quoted in Schmidt's Jahrbücher, No. 10, p. 5. 1857. ↑ Transactions of New York Academy of Medicine, vol. i. pt. ix. p. 377

Concerning the Malpighian bodies and the uriniferous tubes, he says they can only be seen to perfection in transparent preparations, and best of all in thin sections boiled for two or three minutes in water and sulphuric acid (three drops to the half ounce). In order to show the vessels in connexion with the Malpighian bodies, and at the same time the tubes, he injects the vessels with white lead, finely ground in oil, and well shaken with sulphuric ether; and subsequently he boils small portions thus injected in very dilute chloroform. The preparations are then examined in a moist state, or immersed in turpentine.

For the purpose of watching the relations between the tubes and the Malpighian bodies, he simply examined fine scrapings of the kidney after agitating them with water, or boiling them in dilute sulphuric acid, or after heating them in dilute chloroform, but not to boiling point. He determines that the Malpighian tuft or coil of capillaries is enclosed by the expanded extremity or capsule of the convoluted uriniferous tube, agreeable to the conclusions of Bowman and Busch, and in opposition to those of Müller, Toynbee, Gerlach, Bidder, Huschke, and Hyrtl. He never has observed blind terminations or anastomoses of the tubes, except in the frog, fish, and turtle, although he does not deny their existence.

As to the vexed question, whether nucleated cells exist upon the Malpighian tufts, the author does not easily decide, owing to the layer of cells lining the inner surface of the capsule surrounding the tuft. In order to obviate the difficulty, he injected solutions into the ureter, as eventually to distend and rupture the capsular termination of the uriniferous tubes, the Malpighian coil having been previously only slightly injected, and thus it was clearly seen that epithelial cells existed on the uninjected and transparent edges of the tuft. He also obtained his object by scraping off the capsules by fine needles, and washing the scrapings for two or three days in water, by which the epithelium was washed from the capsules and they were distended by water which had soaked through the capsule. All these methods gave the same results, viz., that the Malpighian coil is covered by epithelium, and is not, as Bowman describes it, bare and naked within its capsule. Dr. Isaacs then takes exception to the supposition entertained by most physiologists, as to the functions of the Malpighian body being exclusively confined to the elimination of watery parts of the blood, and states his belief that many of the component parts of the urine pass through the Malpighian tuft in combination with water, their separation not being limited to the cells of the tubes. For this view he gives his reasons. He also entirely dissents from the explanation given by Mr. Bowman, of the physiology of the human kidney, by consideration of structure in the kidney of the boaconstrictor; and shows the want of resemblance between the vascular arrangement of the kidney of the boa and the higher animals, and also the absence of any foundation for the supposed analogy between the efferent vessels in the human kidney and the portal vein.

The author quite confirms the statements of Johnson, Gairdner, and Beale as to the existence of a true fibrous matrix in the kidney, in opposition to those of Rokitansky and Frerichs, who consider such fibrous tissue to be a product of disease. On the addition of acetic acid this tissue, when torn up, is seen to contain elongated bodies, or nuclei. No yellow elastic tissue was seen in it, as described by Hassal. The author alludes to the influence of induration of this matrix upon the small vessels passing through it, interfering with nutrition. Dr. Isaacs has also communicated a paper, with a later date, upon the Function of the Malpighian Bodies.