BIBLIOGRAPHIC NOTICES.

Uber Schleim und Eiterbildung und ihr Verhaltness zur Oberhaut. Von Dr. HENLE.

On the Formation of Mucus and Pus, and their Relations to the Epithelium and Epidermis. By Dr. HENLE. Berlin, 1838.

THE microscope, which in Germany has already been extensively employed in making anatomical and physiological discoveries, has in the work before us been engaged in developing the hitherto secret course of some pathological processes, and in explaining and distinguishing some remarkable products. Our author states at the outset, that pus and mucus, when the latter was secreted in abundance, or diseased, were not to be distinguished by the microscope from one another, although different kinds of mucus were.

Epidermis and epithelium are by him regarded as different names for the same tissue; his description we will give in his own words:

"It is a simple or multiplied layer of cells which covers all the exposed surfaces of the body, all the inner surfaces of its canals and passages, and all the walls of its cavities; thence it is to be found on the external skin, and upon all mucous membranes, from which it enters into the ducts from the glands, and into the finest canals of the glands, on the smooth surface of the serous coats, on the inner wall of the heart and the vessels, even to their finest ramifications. The cells always contain a more or less flat, round, or oval kernel, which again contains one or two still smaller granules. This kernel with its granules always possesses the same form, and the different kinds of epithelium depend on the different development of the pellucid cells. Of these I have distinguished three forms.

"1st. The cells in general have a contour similar to the kernel, only wider in a greater or less degree, sometimes lying close to the kernel, and sometimes forming a wide bladder around it. This form I have denominated Plaster-epithelium. With such the cutis is furVOL. XV. NO. 44. 2 N

nished, as are the greater number of the serous membranes, the vessels and the canals of the glands, with the exception of the testicle. Such is also to be found upon the mucous membranes in the neighbourhood of their external apertures, in the digestive canal as far as the pylorus, in the vagina, on the under half of the neck of the uterus, and the urethra in the female; lastly, upon the ball of the eye, the cornea not being excepted.

"2nd. The cells have a conical figure, with the apex turned towards the mucous membrane, and the base towards the free upper surface. They stand like vessels close to one another, and the kernel forms a projection in the middle of their long axis; this is the cylindrical epithelium which lines the entire of the digestive canal from the stomach down, which enters into the ducts of most of the glands, into the gall bladder, lastly, into the whole virile apparatus with the exception of the vesiculæ seminales, and the cells of the prostate.

3rd. The ciliary epithelium consists of perfectly similar cylindrical shaped bodies, which are only to be distinguished from the others by having cilia on their broad or free end; they are particularly remarkable in the respiratory organs, and the internal organs of generation in the female, commencing at the upper part of the cervix uteri, also in the ventricles of the brain, and, as I lately discovered, on the inner surface of the eyelids, and in the lachrymal sac and ducts.

"The epithelium on the bladder may be regarded as an intermediate form between the plaster and cylinder epithelium, as the cells are stretched and stand perpendicular on the mucous membrane, but are irregular in their shapes."

The cells of the epithelium are described as forming either single or numerous layers. In the single are to be found the cylindrical and the ciliary forms in all parts, and the plaster form on the greater number of the serous membranes, the inner wall of the vessels, canals of the glands, and on the fine mucous membrane of the cavity of the tympanum. On all the other mucous membranes, and on the external skin, the cells lie in layers one over another; and these increase according to the pressure or violence to which they may be exposed, as is evident in the cuticle. In the lowest layer, or the one lying next to the skin, the kernels are of a yellowish red colour, and have a distant similitude to the corpuscles in the blood: the cell here embraces the kernel so closely, that it often appears to be wanting, and perhaps it is sometimes deficient. More externally the kernal becomes more granular, paler, and larger, but the cell which contains it grows much faster than it still more externally the kernel and cell become flatter, till at last they appear like exceedingly fine scales. The form of the cells, at first round, becomes by the pressure of other cells around, polygonal, and in the ultimate scales irregular. In the external layers of the epidermis, the kernel is distinguished with difficulty, and the

little leaves or scales adhere so closely to one another, that it requires very nice dissection to make it apparent; in fact, it could not be done but for the gradual transition which we see constantly going on. Thus these cellules become external then dry and hard, and form a kind of rind, just as the hardened cellular tissue of plants forms their bark.

From these anatomical data, our author infers physiologically that the epithelium and epidermis candot be regarded as the unorganized product of secretion, or, in other words, as hardened mucus, although it is evident that their nutrition depends on the vascular tissue situated beneath them, on the changes of which they are so clearly dependent. From the facts adduced, it is still less likely that the cells should develope themselves in an independent manner, as they not only increase in volume, which possibly might be ascribed to a physical absorption, but the little body contained within them goes through its regular stages. The chemical quality of the cells is also changed; in this development the deep layers being dissolvable in acetic acid, whilst the superficial layers as well of the plaster epithelium as of the epidermis, are not affected by it.

The epidermis and epithelium stand in a double relation to the secretions of the skin and glands. They permit fluids to pass both from without inwardly, and vice versa, whilst they themselves remain perfectly passive.

"But in regard to the secretions, I have long suspected that they play a very active part, because their cells contain manifestly drops of fat in those secreting organs whose secretions contain a remarkable mingling of fat. An observation which I have made lately changes this suspicion almost to certainty, viz. that the liver internally consists of the cells described throughout its whole parenchyma, and that the kernel of those cells is almost constant in size of a diameter of 0,0030 to 0,0033", and is generally round, although sometimes flattened by pressure, whilst the cells themselves are polygonal, mostly quadrangular or pentangular, with a diameter of 0,007""."

In drawing the parallel of similitude between the epithelium and epidermis, our author says:

"It is well known that in proportion as the cuticle is reproduced from beneath, its superficial layer is cast off, and this ordinarily is accomplished in the form of little scales. If any portion of a healthy limb be bandaged closely for a period of some weeks, it is quite astonishing what a quantity of these scales will be found on opening it. By pressure the formation of new cells on the epidermis will be increased, and either welks or corns will be produced. Also similar scaling off of the mucous membrane is to be found in particular places in a state of health, which takes place constantly and regularly, with'

this difference, that the particles thrown off do not present the appearance of dry scales as those of the epidermis, but as a viscid membrane always saturated with much moisture, which forms the overlaying coat of all mucous membranes, so far as they can be reached from externally. The surface of the eye-ball, the entrance to the nose, mouth, and pharynx, the oesophagus, the vagina, are always covered with this mucous layer, which can easily be scraped or wiped off, and which all cleanly persons are anxious to remove as much as possible."

M. Henle then proceeds to show, how Nature in every instance provides means for the removal of this coat of mucus lying over the epithelium, and compares the secretion of the mucous glands to that of the respiratory glands of the skin, by means of both of which the layers of epithelium and epidermis which are loosened, are finally removed or dissolved. Great difference is to be found in the powers of regeneration of the epithelium, that of the serous sacs possessing the least.

"The cylinder and ciliary epithelium are only cast off under peculiar circumstances, either by disease, or at particular periods, in the healthy body."

Thus the whole intestinal canal of the infant loses its epithelium the first week after birth, and large flocculent patches of it are discoverable amongst the discharged fæces; the stomach casts off its external coat of epithelium during digestion, the same occurs in the female organs of generation after delivery, menstruation, &c.; "after the latter, the fragments of epithelium are distinctly to be found in the discharge which succeeds it."

Thus having considered mucus as produced in a state of health, M. Henle proposes that it should be called by the name which it really merits, "cast off epithelium." He next proceeds to the comparison of those membranes under various circumstances of disease in a very ingenious manner, showing that the purulent products of both are similar, as well as the disposition and course of action which gives rise to them. Mucus and pus are distinctly stated to be similar, that is, each consisting in a multitude of these little molecular bodies, with their envelopes, floating in greater or smaller numbers in a more or less inspissated fluid.

"The little mucous bodies (Schleimkörnchen) which remain after the removal of the epithelium on the mucous membrane where effusion has existed, are not distinguishable by the microscope from the little bodies which are found in the serum of blisters, and bullæ of the epidermis, in the pus of pustules, and in the watery exuda