ing simple round cells, corresponding to the primary formative cells of areolar tissue, the future areolar tissue corpuscles. Most probably, he continues, the ossification proceeds by the gradual formation of calcareous salts without any distinct limitation in the inter-cellular structure, the cells developing into dentate bone-corpuscles. The intervention of cartilage is not met with, nor any pre-existing cloudiness owing to calcareous deposit. Thus we have a direct ossification of areolar tissue. In the ossification of cartilage, however, the process is more complicated, consisting not of a mere change (Umwandlung) of substance, but of a total transformation (Umgestaltung) of structure, which renders the investigation of their histological changes so difficult. The best method of examining is to take fine sections, made in various directions through the edge of the calcification of the diaphysis of a fresh fœtal long-bone. We here sce, as has been in part long known, that the cartilage cells, hitherto equally divided, assume a direction corresponding to the future bone-structure, and that in the cartilage of long-bones they become placed in rows, which are conspicuous, on transverse section, as roundish groups. The single cells increase in volume at the expense of the stroma; their contents become transparent, and show a large nucleus with nucleoli. In the walls of the cartilage cavities, or canals, a deposit takes place of dark granular earthy elements; and this calcareous deposit forms limits between cartilage and bone; but we as yet have not the microscopical elements of bone-substance. The cartilage cells are contained, yet unchanged, in the cartilage corpuscles, encrusted with lime, whose opaque character renders the observation of their metamorphosis difficult. In the place of a single cyst-like nucleus, more like it are found, which fill the mother-cell, and, after its dissolution, become free. It is this brood of cells, corresponding to the nucleus of the cartilage cell, which constitutes the contents of the calcified cartilage cavities, and also the starting-point of all following changes. The fact that in the ossification of cartilage an endogenous formation of cells takes place in the cartilage cells a process which is to be distinguished from the increase of cartilage cells by division before ossification -has hitherto been thought by observers to be connected with the formation of the medullary elements of bone, having, according to them, no reference to the origin of bone-substance itself: whilst, in fact, a portion of the cell-formation is covered with vessels-fat cells, or marrow cells-surrounded by a layer of soft, striped, intervening substance, which lines the inner wall of the carti lage cavities. Of pure bone-structure, nothing was hitherto to be seen: but now it forms itself for the first time by direct ossification of the blastema, by change of its cells into bone corpuscles, and its intercellular substance into homogeneous non-granular osseous stroma.

Hence it is that the first bone-substance occurs in the form of a canal lining each calcified cartilage cavity, which becomes obvious on a transverse section as a circle surrounded by a simple row of bone cells. This bony cylinder thickens from within outwards by successive ossification, so that each cartilage canal is gradually more or less filled by a system of concentric long lamella. The quite uniform, concentrical arrangement of the lamellar substance of the tubules is obvious, as in the interior of each medullary canal a lamellar formation and successive ossification from the centre outwards occur. In this way the individual bone tubules of the newly-formed bone-substance must be, at first, still separated from the calcified bone-substance surrounding, and from each other. The calcified basis of the cartilage gradually passes into homogeneous bone-structure, whether the lime particles fuse into a homogeneous mass or are re-absorbed. After that, the granular lime-deposit disappears entirely, and along with it the organic structure which pertained to it; and the already-commenced resorption of the cartilage stroma proceeds further after the removal of the lime, in order to make room for the new bone-structure. Then the single laminated bony rings close in nearer together, until, after complete disappearance of the inter

vening cartilage layer, they touch each other. Hence it follows that the basis of the primordial cartilage has no part in the formation of bone-substance. This result from observation, according as it does with the chemical differences between bone-cartilage and the hyaline-cartilage substance, constitutes an objection to the theory of persistence of the latter in bone. One must therefore fall back for an explanation of the ossific process, either upon the theory of a chemical change, or that of a molecular displacement of the one substance by the other. The organic basis of bone is as little identical with the basis of the hyaline cartilage anatomically as chemically. The last is incapable of a true ossification: its calcification is one indeed for the most part accompanying ossification, but is, in fact, a process differing from it. The bone-substance occurring in cartilage is newly formed in the cartilage cavities, nevertheless it does not obtain immediately as such, but there precedes it the formation of a blastema, consisting of simple cells and soft intercellular substance. This blastema accords in all relations with the ossified layer of the periosteum, and like it, must be looked upon as belonging to areolar tissue. Its ossification takes place through absorption of calcareous matter by the homogeneous intervening substance, and by the change of its cells into bone corpuscles. Also, in cartilage the ossification is preceded by the formation of areolar tissue. The part taken by the cartilage cells in the ossific process consists in their acting as mother cells of such cells as the cartilage corpuscles exhibit, surrounded by ossified areolar tissue and developed in a radial form. Never are the cells of the primordial cartilage changed, as such, into bone cells: they differ both in number, size, and disposition. In some places, such few bone corpuscles were seen inside the transparent contour of a cartilage cell, that it was evident that the production of other cells by them had been liniited to but few. Pure bonesubstance is limited to the circumference of the cartilage cells, whilst this itself is surrounded by calcified, or, in rhachitic bones, by still hyaline cartilage stroma. Such appearances give rise to the assumption that the bone corpuscles correspond to the nuclei of cartilage cells, or the cartilage cell thickened by an interior deposit. This view does not hold good in the ossification of fœtal cartilage. The ossifying process of the primordial cartilage has shown, on the one side, that the bone-substance, as it agrees chemically with the substance of the areolar tissue, so also, histologically, it must be referred to the elements of areolar tissue; and, on the other hand, the capability of a direct ossification must be refused to the tissue of hyaline cartilage, because neither its basis nor its cells persist, as such, in the analogous elements of bone. The proposition that a bone-formation is, in like manner, possible out of cartilage as out of areolar tissue, by deposit of calcareous matter in its basis, is, according to the author, hereby confuted; and at the same time, in his opinion, the theory of the identity of cartilage with bone and areolar tissue, which was one of the most important supports of that proposition, removed.

EPITHELIAL SYSTEM.

On the Ciliated Epithelium and Ciliary Movement in the Generative Organs of Mammalia and Man.-O. Becker,* premising the necessity of examining the inferior animals as a guide to our researches in man, and adverting, as an example, to the fact that he had been led to find ciliary epithelium in a part of the human epididymis, owing to its discovery in the pig,-proceeds to advert to the condition and character of the epithelium in various portions of the human genital organs. He first considers the female organs, and then the male organs, after birth; and afterwards he proceeds to notice the existence of ciliated epithelium in the embryo. He then enlarges upon the general subject of ciliary

* Untersuch. zu Naturlehre der Menschen und der Thiere, Band ii. Heft 1, p. 71. 1857.

movement in the ducts of the genital glands, and concludes by a consideration of this movement in closed cavities.

As regards the epithelium of the female organs after birth, Becker notices several differences. Whilst Kölliker describes the pavement epithelium of the vagina as passing into the ciliated form in the cervix of the uterus, Henle and Gerlach seemed to have traced it towards the fundus; and in the dead bodies examined by Becker it was also found to be so. The average length of the cylindrical cells was 0.036 millimetre. In the Fallopian tubes and on the fimbriae they were only about one-half this length. On the posterior surface of the fimbria, ciliary epithelium existed, in various transitional forms, passing into the pavement epithelium of the abdominal cavity. The author notices the observation of Bischoff,* that the inner genital organs after birth, until puberty, are wanting in ciliated epithelium; and also that of Valentin,† who describes it as wanting in young animals and in the woman at the catamenial periods, and, for the most part, during pregnancy. Becker says that this is only correct as regards the mucous membrane of the uterus. As regards the fimbria and the tubes, on the contrary, the epithelium in the newly-born mammals and human being is ciliated, and this is specially seen at the free borders of the fimbriæ, and at the uterine end of the tubes. In very young rabbits the movement of the cilia is most easily to be seen. Becker also, contrary to Bischoff, declares that the ciliated movement of the epithelium of the Fallopian tubes and fimbriæ exists in the pregnant rabbit, and that it does not cease on the passage of the ovum. In the uterus of the newly-born child no ciliated epithelium exists, and this is also the case in the rabbit. At the time of puberty, however, ciliated epithelium is found in animals at the fundus of the uterus. The author then alludes to the observations of Kölliker, who found that during the catamenial periods and pregnancy, the time of periodic removal and reformation of epithelium, the ciliated form of epithelium alone was concerned; but asserts that, as far as he himself has examined the matter, ciliated epithelium was to be found at the top of the horns of the uterus in the rabbit that was pregnant. As regards the epithelial lining of the accessory ovaries (Kanale der Nebeneierstöcke), which Kölliker says are probably of a ciliated character, the author declares that it varies according to the stage of development of the ovary; but that in two newly-born children, and once in a woman, aged twenty-nine, who possessed a greatly-developed parovarium, the ciliary projections were easily seen. This was also the case in the parovarium of a rabbit fourteen days old.

Proceeding next in order to the male organs, Becker speaks of the ciliated epithelium of the epididymis. He had examined very many of the lower animals-such as the amorous sparrow, the swallow, the fowl, the goose, duck, pig, deer, horse, rabbit, cat, and dog-and in all he had found the vasa efferentia to be possessed of a simple ciliated epithelium. He notices, however, certain differences observable in several of these animals, especially as regards the course and direction of the vasa efferentia, which do not concern us here. He declares the presence of a double epithelium in the epididymis of all mammals; of which one, a simple ciliated epithelium with conical cells, covers the vasa efferentia; whilst the other, a complex laminated layer with cylindrical cells, beset, according to age and species, with unusually long cilia, occupies the entire tube of the epididymis as far as the vas deferens, and there, by means of a simple form of cylindrical epithelium, passes into the pavement variety. The epithelium of the canal of the epididymis at the time of birth and before puberty, consists of cells, of which the uppermost layer is hardly larger than the younger ones beneath. As the epididymis grows, these elongate and

• Entwicklungsgeschichte der Säugethiere und des Menschen, p. 492.
Lehrbuch der Physiologie, Band ii. p. 23.

become laminated. The fibrous tunic of the seminal canals of the testis is so firmly united in the rete of Haller with the areolar tissue of the corpus of Highmore, that the canals almost appear to be without any special membrane. In the "coni vasculosi" there intervenes, between the fibrous layer and the structureless membrane, a circular layer of contractile fibre cells, which appears to be wanting at the summit of the cones. In man, as in most animals, the vascular cones possess a simple ciliated epithelium, whose cells are sharply contoured, being conical, with cilia from 0008 to 0010 millimetre long. It is very persistent, and is to be found in the newly-born subjects just as in the adult, and can often be expressed out of the seminal canals connected together so as to form hollow cylinders. Becker speaks of his finding this epithelium even in diseased parts, in which induration, along with obstruction of the excretory ducts, has taken place, and describes the cilia in one case of a testis destroyed for the most part by fibrous cancer, as distinctly seen in a state of motion.*

As to the canal of the epididymis, the epithelium is found to be laminated, the cells being quite cylindrical, perpendicularly placed, with strong but minutely contoured walls, very long, and with large nuclei. The head of the epididymis offers the longest cilia that can be seen in the human body. The epithelium here is remarkable for its frailty and liability to change, and its proneness to reproduce itself. At birth, as well in man as in animals, it is but slightly formed; and in young children, no cilia are to be found in the whole course of the canal. But about the time of puberty, the cells exhibit fluctuations in the size and length of the cilia, the contour becomes bolder, the contents granular and less transparent, the cell-membrane indented, crumpled, and in some cases folded together; but the character of the epithelium in the epididymis seems in a great degree to be dependent on the quantity of perfect seminal fluid therein collected; and this accords well with the completeness of the epithelium found in animals that are yet rutting. The cilia of the epithelium in the head of the epididymis are peculiar, as indicating a tendency to adhere to each other, thus giving the appearance as of a solid stem projecting from the interior of the cell, but not of cilia at the edge of the cell. Becker had never seen cilia on cells removed from the lower end, and had never missed them in the head of the epididymis. At the lower end he had observed epithelial cells of unusually large dimensions. In the vas deferens the

epithelium was simply cylindrical, and in the upper third passed into the pavement form, which covers the vesiculæ seminales. The efferent ducts of the testis are not, however, the only places possessing ciliated epithelium. The so-called non-pedunculated hydatids of Morgagni, situated in the head of the epididymis, and described by Luschka as being generally, though not always, in connexion with the seminal canals of the part, are seen to possess ciliated epithelium as well as seminal threads, which two structures appear to bear a certain proportion to each other.

The ciliated epithelium of the hydatids is always small and varied in form; at one time regularly cylindrical and slightly conical, at another time irregular and small. In like manner the pedunculated hydatids or cysts which generally exist where the vesicles of Gosselin are found, as remnants of foetal structure, as also the parovarium and the "uterus masculinus," contain ciliated epithelium.

As regards the embryonal structures, the author ascertained that ciliated epithelium does not exist in the Wolffian bodies of the rabbit. Their existence at birth lead to the supposition that perhaps the Fallopian tubes and

For a beautiful instance, with illustrations, of the presence of ciliated as well as pavement epithelium in cysts within the testicle, see vol. vii. of the Pathological Society's Transactions, p. 241, as described by Mr. Athol Johnson. The specimen was removed from a child aged two years and three quarters, and was probably congenital.

the head of the epididymis of the embryo might possess ciliated epithelium, but, although sought for in various embryos, none was found; nevertheless, their existence before birth seems certain,

The author then proceeds to demonstrate the best method of watching the movements of the ciliated epithelium, and describes those which he observed for the space of two hours, in a part of the testicle which had been removed, from a man aged forty-two, during life. He speaks of the ease with which the stream of fluid established by the cilia in a direction from the seminal gland, can be watched in certain animals, the walls of whose vascular cones are very transparent, and this the more so as seminal particles are carried along. He thinks that the stream in the vascular cones is not parallel with the long axis of the vessel, but observes a spiral direction.

As regards the ciliary movement in closed cavities, the author alludes to a case of cysts of the testicle related by Billroth in the 'Deutsche Klinik,' 1856, No. 10.

Upon the Epithelium of the Gall-Bladder, and also upon an Intermediate Metamorphosis of Fat.-Under this title R. Virchow has a paper of the following nature. After alluding to his former mention of a peculiar appearance in the cylindrical epithelium of the gall-bladder-i.e., its gradual filling with finely granular fat, he draws a comparison between this and analogous processes in the intestinal epithelium cells, as also the changes in the fatty metamorphosis of cells. In general, but not invariably, the nucleus of the cells remains complete. Often also a collection of finely granular fat was observed in the netlike folds of the mucous membrane itself of the gall-bladder, and in one case in the sub-mucous tissue, anastomosing canals were seen, in which larger and smaller fat masses were seen. Virchow alludes to the observations of Gobley, to the effect that only a very slight quantity of the neutral fat of the bile is found in the excrements, and hence most probably it is reabsorbed in the intestines. This absorption is thought by Virchow to occur in the gall bladder. He observed the epithelium of this organ in man, the dog, and cat, and found it in all places to be comparable to the intestinal epithelium. In the dog the cylinders are very long, showing their free surface and a side view very well. On the free end of the cells a broad bright border, with radiating stripes, is to be seen (just as Kölliker has pictured of the intestinal epithe lium), having, when quite fresh, a smooth margin. After a time, as Kölliker shows in the intestines, the margin becomes toothed, and the projections often have the look of cilia, and other appearances arise-such as the lifting up of the cell membrane from the contents, as Kölliker and Remak had seen in the intestinal epithelium.

As regards the absorption of fat, first of all a finely granular fat entered, and later on fat in large glistening drops. Originally the fat exists at the uppermost parts of the cell, close under the homogeneous border, the deep parts lying free. It gradually passes deeper, until it extends and fills the entire cell, excepting where the nucleus exists. At this time, owing to the linear direction of the fat drops, they have somewhat the appearance of primitive muscular fibre undergoing fatty degeneration. Afterwards the fat ceases in the outermost parts of the cells, and finally it may only be seen at their bases. Along with the fatty infiltration, an infiltration of finely granular or finely crystallized brown or brownish-red pigment, occurs as well in the epithelium as in the superficial layers of the areolar tissue, easily attributable to a post-mortem deposition; but this is disproved by the examination of animals quite recently killed. In them the fatty infiltration of the epithelium coincides with the later periods of digestion, and the decrease of the fatty contents in the hepatic cells. It may be a question whether the fat in the * Virchow's Archiv, Band ii. Heft 6, p. 574. + Gazette Médicale de Paris, Sept. 1856.