Chronicle of Medical Science. CHRONICLE OF MICROLOGY. 1. PHYSIOLOGICAL MICROLOGY. Pacinian Corpuscles.-In the skin of the beak of the duck and goose, says Dr. Grandry, though after the common type of the corpuscles found in other birds, they are, nevertheless, different in the structure of the central bulb, and approach to those described in the woodcock by Leydig. They are formed of a connective envelope and of a central bulb. The connective envelope is made up of two clearly distinct parts; one, external, of concentric capsules, and the other internal, of connective tissue of fine fibres crossed in all directions, but whose inner parts seem, nevertheless, to form layers concentric to the central bulb, at least after adding acetic acid. The inner part of the envelope is so much coloured as to hinder the examination of the corpuscles, if acetic acid has not been added In relation to the structure of the central bulb, two kinds of Pacinian corpuscles are discernible; the first altogether resemble the corpuscles noted in birds, the second present much analogy to those described by Leydig. In the duck, as in the woodcock, one finds in the central bulb rounded and quadrangular bodies in two rows at the sides of the central fibre (central canal of Leydig), regularly distanced the one from the other, and separated by finely granular matter, having no relation with the envelope, from which they are rather distant, and separated from it by the same substance which separates them the one from the other. The bodies show in their interior a rather opaque point, which may be considered as a nucleus or nucleolus, according to their interpretation as cells or nuclei. The central fibre of the Pacinian corpuscles of the duck or goose seems to resemble altogether that of the corpuscles of other birds; but in these animals one finds the terminal extremity of the fibre very voluminous and more granular than that found, e. g. in the Pacinian corpuscles found in the pigeon, in the space between the tibia and fibula. I have not found corpuscles in which the fibres, as in the cat, bifurcated near its end; but I have seen a division of the fibres a little way beyond its entry of the central bulb, and then, in one and the same corpuscle, one saw two central bulbs reunited by one end. All the characters here indicated are seen very readily by the action of weak acetic acid only, but all becomes much more plain if weak chromic acid is employed in the preparation. The woodcock's corpuscles, besides the peculiar bodies, show striæ: I never could find of them in those of the duck and goose. any The chloride of gold has also a remarkable action on those corpuscles. If the skin of the beak of the duck or goose in a solution of chloride of gold, of 1 in 100, for twenty-four hours, the action being complete, one sees the whole of the bulb deeply coloured, and continuing with the fibre in such fashion that this seems to end as a swelling, which is no other than the whole bulb. This reaction seems evidence in favour of Leydig's opinion, which regards the whole bulb as the termination of the nerve; but the less complete degree of reaction, and hyperosmic acid especially, show quite clearly the fibre continuing entirely through the central bulb, and that, at least, the peripheral part of this has not the same structure as the centre, and that that which Leydig considers as a canal, is the immediate continuation of the axis cylinder of the fibre which enters the corpuscle. If the chloride of gold has acted incompletely, one sees forthwith that the centre is attacked, then the summit; even the whole is not unfrequently attacked, and the fibre is more marked in the centre. As to the Leydig corpuscles, they take colour just like the rest of the central bulb; and in the case of complete reaction, it is impossible to trace them. The chloride of gold, which does not attack the envelope, and, on the contrary, colours the entire central bulb, tends to show that the tissue surrounding the fibre has more of the character of nerve substance than of connective tissue. The hyperosmic acid best shows the central fibre and the granular terminal swelling, yet it also, but less, colours the rest of the central bulb. By this reagent one sometimes sees the central fibre end as a little swelling in the midst of the ordinary terminal swelling. Beside the Pacinian corpuscles, in the beak of the duck and goose is found another form of nerve-ending, as to the structure of which I am doubtful, especially as to the termination of the nerve. author then refers to the plate accompanying his paper.-Journal de l'Anatomie, &c. (Robin's), July and August, 1869, p. 390. The Termination of the Skin-nerves - Meissner's Corpuscles.-Dr. Grandry found he could obtain the best results in the above investigation, by the reagency of a bichromate of potash, or of Müller's solution. Of Meissner's corpuscles, he says:-The envelope is made up of condensed connective tissue, as Kölliker admits, and, with him, he believes that the transverse nuclei seen on the surface, especially by action of acetic acid, belong to the connective tissue; in no case could he find the spiral disposition of the fibre reduced to the state of cylinder axis. As to the central bulb, he considers it altogether analogous to those of the Pacinian corpuscles, referring in this to that which he has said of the reaction of chloride of gold on them. But yet he would call attention to the existence of formed elements within this central bulb, a fact sometimes denied. The course of the medullary fibre is exactly such as most observers describe it-it rolls in large spiral turns around the corpuscle, and thus reaches its summit always within the envelope, without penetrating the central bulb. Does the medullary fibre always take its course external to the central bulb? This the author does not believe, for he has, by use of osmic acid, distinctly seen the fibre altogether within the envelope, and, equally, Müller's solution has shown it him penetrating the central bulb, yet furnished with medulla. As to the way of their ending, opinions vary much. Rouget says that the fibre ends in the central mass, being, in such fashion, continuous with it, that the central bulb might be considered as the fibre expanded, and, as for him, the formed elements are analogous to those found in the terminal plates of the muscles. In the author's experience, the nerve does not end in becoming continuous with the central mass, but indeed with the formed elements formed within it; and this quite reminds one of the terminal enlargements of the Pacinian corpuscles. The author then relates the rest of his observations made on transverse sections of Meissner's corpuscles of the pulp of the fingers, treated with Müller's solution. Within them. one sees bodies more or less spherical, granular, varying from 008 to 01 mm., which seem to be often isolated, and to have no relationship with a fibre or with the envelope, and are situated most frequently near to the vertical axis of the corpuscle. Attentive examination of good preparations allow a distinction, beside the spherical bodies, of excessively pale fibres, at different levels, not anastomosing, going off from the envelope, not lost in the granular substance, but continuous with the formed granular bodies, so that the latter seem pediculated. A noteworthy fact is that the fibres leaving the envelope do not go directly to the granular bodies, but, before reaching them, describe greater or less sinuosities. The author has seen the double-contoured nerve-fibre pass into the interior, become reduced to the state of cylinder-axis, and continuous with the granular bodies. Finally, says the author, the only difference between Meissner's and Pacini's corpuscles is, that in the skin corpuscles the fibre gives off a greater number of endings; though, in the Pacinian, three may be found.-Ibid., p. 395. The arachnoid space a lymphatic space, and its connexion with the perichoroid space.-Dr. G. Schwalbe, of Amsterdam, has, in the course of last year, described a system of cavities between the choroid and the sclerotic, a perichoroidal space, and expressed the opinion that this might be a lymphatic space. He says:-I have now succeeded in the production of certain evidence in favour of these suppositions by a single experiment, which at the same time demonstrated another important matter of fact, namely, that the arachnoid space of the brain and spinal marrow is likewise a lymphatic space. The experiment consists in this, that in an animal bled to death from the femoral artery (for the purpose I have generally made use of rabbits, but in dogs also the same result is easily attained) one cautiously lays bare a portion as small as possible of the dura mater cerebri, and then beneath it, by a puncture, a solution of Berlin blue with steady force is injected into the arachnoid space. As a constant result one gets in the first place a fine filling of the lymphatic vessels and glands of the neck. A closer investigation shows that the connection of the arachnoidal space with the lymphatic vessels of the basis cranii takes place by the jugular foramen. It shortly comes to pass that the lymphatic twigs, passing out upon the under surface of the basilar part of the occipital bone and the superior cervical vertebra, where they form a plexus provided with small lymphatic glands between the processes of the longus capitis and colli, out of which lymphatic vessels are evolved which are dispersed in the direction of the lateral parts of the neck, about here to pass away in the deep cervical glands. The injection often reached to the inosculation of the lymphatic vessels in the veins and beyond them, so that in the lower part of the neck one sees the veins which go to form the vena cava superior filled with blue injection. As was to be expected the arachnoidal space also of the spinal marrow, in its whole length, is filled by the above procedure. In one case the lymphatic glands were in particular well filled by a successful injection. The injection had not penetrated to the thoracic duct. I believe that this result admits of no other interpretation than that the arachnoidal space of the spinal marrow stands in direct connection, not only by interposition of the arachnoidal space of the brain, with the lymphatic system. With the perivascular canals of the brain and spinal marrow described by His, as well as with the lymphatics of the pia, the arachnoidal space stands in no direct relation. The injection matter reaches easily into the subarachnoidal spaces, but always remains separated by the pia-mater from the lymphatic system of the brain. A communication is, in the first place, probably permitted between the efferent lymph courses on or after their passing out by the cranial aperture. None of the injection has been observed to have passed into the ventricles of the brain. A quite peculiar interest envelopes our injection experiments, in that also lymphatics are filled which have been hitherto but little or not at all studied. One gets in this way a beautiful network of fine lymphatics injected in the nasal mucous membrane. It appears, further, in this, that the space filled with the perilymph between the cutaneous and bony labyrinth is a lymphatic space, there the injection of the arachnoid space reached it by way of the Porus acusticus internus. Finally, there yet remains to be mentioned, as the most The important result, the injection of the perichoroidal space. injection fluid reached from the arachnoid space through the optic canal into the orbit, and in the next place filled the space between the inner and outer optic sheath, which subsequently appears as if it were a continuation of the arachnoid space; the injection at the same time enters a space which is found between the retractor bulbi and the optic nerve, thence it passes directly into the capsule of Tenon, from thereabouts to extend into the perichoroidal space by the openings of communication by me lately described. The latter is, by the procedure described, often so completely injected, as one easily obtains this by a puncture through the sclerotic. We thus sce lymphatic currents of the three higher organs of sense in close connection with the arachnoid space. This appears to be a common reservoir of lymph abstracted from the organs of sense above mentioned, and thereby obtains a high significance. The opinion that the serous sacs are no other than lymph spaces, gains new support by our experiments.-Centralblatt für die Medicinischen Wissenschaften, June, 1869, pp. 465-7. Red blood-corpuscles of oviparous vertebrata.-Mr. W. S. Savory, in a paper read before the Royal Society, states that, of all vertebrata, the red corpuscle is, in its natural state, structureless. When living, no distinction of parts can be recognized; and the existence of a nucleus in the red corpuscles of ovipara is due to changes after death, or removal from the vessels. As the oviparous red cell is commonly seen the existence of a "nucleus" is too striking an object to escape any eye, but that it is so is due to the circumstances under which the corpuscle is seen, and the mode in which it is prepared for examination. It is possible to place blood-cells under the microscope for examination so quickly, and with such slight disturbances, that they may be satisfactorily examined before the nuclei have begun to form. They may then be shown to be absolutely structureless throughout; and, moreover, as the examination is continued, the gradual formation of the nuclei can be traced. The "nucleus first appears as an indistinct shadowy substance, usually, but not always, about the centre of the cell. The outline of it can hardly, for some seconds, be defined; but it gradually grows more distinct. Sometimes it never forms so as to be clearly traced in outline, but remains as an irregular shapeless mass, in its greater portion very obscure. Sometimes only a small part, if any, of an edge can be recognised, most of it appearing to blend indefinitely with the rest of the cell substance. Sometimes it happens that in many corpuscles the formation of a nucleus does not proceed even so far as this. No distinct separation of substance can anywhere be seen, but shadows, more or less deep, here and there indicate that there is greater aggregation of matter at some parts than at others. Occasionally some of the cells present throughout a granular aspect. When the nucleus is well defined, the cell wall is strongly marked; when one is confused the other is usually fainter. This, however, does not apply to colour; on the contrary, when the nucleus is least coloured it contrasts most strongly |