ལ.. ལུ་ས་བ་ K Fig. 4. Various forms of fatty epithelial cells, single and in flakes, as described in the text. coherent, showing a linear interval of separation from each other, resembling in this particular the lung of the batrachian. k. Fatty epithelial cells, apparently disintegrating. In size, the fatty epithelial cells vary so considerably, that no standard can be given as the average. A very few may be found smaller than a medium-sized normal lungepithelial cell by far the majority are larger, and some much larger. The smallest and the largest are generally the least angular in outline; the one perhaps from youth, the other from distention. Still, singularly-shaped cells, with abruptly cut margins, seeming to indicate that the cell has been partially disintegrated, are seen of all sizes. Bronchial columnar epithelium is found freely in the several conditions of withered but not fatty; fatty and swollen; partly fatty and partly withered. In some of these detached bronchial epithelial cells the nucleus alone is fatty; or the columnar part alone is fatty; the nucleus being merely granular; or the whole is made up of oil-globules of different sizes, no nucleus being left. Of course, more might be observed on the minute differences presented, but the above may suffice to establish the fact that what is thus described really is epithelium in a KAIJEL Fig. 5. Bronchial columnar epithelium, from lung adjoining yellow tubercle. + 450. state of fatty degeneration, and not any of the morbid cell-forms which result from inflammation, and are generated in inflammatory exudation. In answer to the first question which is usually put, How are these cells to be distinguished from the granule cells of inflammation? it is to be remarked, that the easiness of making the distinction depends entirely upon the individual cells selected. A young gland-cell in one viscus is very much the same in appearance as a young gland-cell in another, however clear may be their ultimate distinctiveness at maturity. So, also, of pathological cells: one may find some specimens in every diseased product not distinguishable from others belonging to a very different diease. We are ruled by the form of mature cell which preponderates, and take that for the type. So here, by the same rule, we find certain cells which are so manifestly epithelial cells more or less fattily degenerated, and we can trace such marked gradations in them, that we need feel no hesitation about our conclusion because a few of the cells, if taken alone, could not with certainty be placed in the same class. There is no room for doubting, for instance, the nature of a flake of pavement-epithelium in which the cells still cohere and fit in by their edges, whilst they present various degrees of fatty degeneration. Neither can any doubt exist when we are viewing fatty columnar epthelium from the adjacent bronchi. The 3. The compound Corpuscles of Tubercle, or many-nucleated Cells.-These are large cells, which contain several separate nuclei. We do not find many of them in the mass of mature tubercle, and what there are lie here and there, and not in aggregated heaps. Neither do we find them in those air-vesicles which are nearest to healthy lung. Here the epithelium is only fatty. But between the air-vesicles which contain the fatty epithelium and those which are crammed with complete tubercle, these cells are numerous. They were first described by Virchow in 1851, and by Van der Kolk in 1852. former mentions "cells with five large, oval, granulated, nucleolated nuclei." The latter states that the cells nearest the wall of the air-vesicle are the smallest, contain only one nucleus each, but when cast off increase greatly in size by the imbibition of fluid, and are filled for the most part with numerous nuclei. "The cells which are placed in the middle of the air-vesicle are thus the oldest-i.e., they are farthest removed from its walls, longest exposed to the influence of the surrounding fluid, and thus, also, the largest." By both observers these cells are considered to be morbid epithelium; and by both the contained nuclei are believed to be set free by dissolution of the enveloping cell, and then to constitute the small cells described by Lebert and others under the name of tubercle-corpuscles. For the further interpretations, somewhat differing, of the two authorities, I must refer to the only sources of my own acquaintance with them—the accounts severally given by Dr. Jenner and Mr. Paget.† My own observations lead me to conclude-(1.) That the many-nucleated cell may be found of the largest size, and containing its largest number of nuclei, whilst close and adherent to the wall of the air-vesicle; (2.) That no successive strata of cells, becoming more and more nucleated as they advance free from the wall towards the centre of the air-vesicle, can commonly be made out; (3.) That no distinct lamination of cells of any * British and Foreign Medico-Chirurgical Review, vol. xi. p. 186. 1853. kind upon the wall of the air-vesicle, as if they had been thrown off in successive and distinct layers, is observable; (4.) That cells equally large, equally centric as regards the air-vesicle, are numerous, in which either only one nucleus, or none at all is discernible, the whole being in some stage of fatty degeneration; (5.) That a rather small cell may contain several nuclei, whilst one much larger, as just remarked, may have only one; (6.) That whether or not the nuclei of the many-nucleated cells, if set free, would be identical with the free tubercle corpuscles, they are not the principal, still less the only, source in which these originate. b. Another with one lateral nucleus, very distinct, and closely resembling a free tubercle-corpuscle. c. An aggregation of coherent nuclei, but no distinct parent-cell-wall around them. d. A large cell. having a second cell enclosed with two nucleated nuclei, taken from a highly organiz- e. The same cell at different foci. f. An apparently shrivelled compound cell. g. A compound cell, partially disintegrated. Their The many-nucleated cells, or compound corpuscles, are darker than any other of the cell-forms seen in examining tubercle. They have often a clouded, yellowish-brown aspect, and at first glimpse are readily mistaken for large glomeruli. They are usually plump and roundish, ovoid, or pyriform, and strikingly differ in appearance from equally large, but flatter and more or less angular, epithelial cells which are only fatty. nuclei lie at different depths, and cannot all be seen distinctly at once. Distinct and in sharp relief, indeed, it is only by chance that any of them can be seen, owing to the dense nebulousness of the cell in which they are contained. So far as can be distinguished, these nuclei, whilst within the cell, are ordinarily larger, plumper, and more regular in outline than free tubercle-corpuscles; they look less hard and compact, and their granules less distinct. Occasionally, however, we catch sight of one close to the wall of the containing cell, which appears to resemble closely an ordinary free tubercle-corpuscle. And, in examining large miliary tubercles, grey throughout, I have sometimes seen a faded, shrivelled, flat, semi-transparent cell, no longer granulous, in which lay three distinct very characteristic tubercle-corpuscles. (Fig. 6, f.) This I took to be a compound cell, on the eve of dissolving and setting free its nuclei. It is not unfrequent for one of the nuclei in a compound cell to be larger than the rest, and to possess a nucleolus. There may even be two nucleolated nuclei side by side in an oval cell, contained within a large compound cell having the ordinary non-nucleated nuclei. This form is rare. I have only found it in the highest type of tubercle-viz., the grey miliary, with fibrillated matrix. (Fig. 6, d.) Usually, there is only one nucleolated nucleus in a compound corpuscle, however numerous the fellow nuclei may be. This nucleolated nucleus may be supposed to represent the original nucleus of the epithelium cell; the remaining nonnucleated nuclei being formed secondarily, as the cell increases in size, from mere corpusculation of plasma imbibed whilst the cell is still adherent to the wall of the air-ves icle. Whether such growth of cell, and multiplication of nuclei within it, also go on after detachment from the wall of the air-vesicle, cannot, I believe, be decided either way by anything we can find on inspection. If the cell can grow after severance from the place of its birth, or if it be, from the time of its detachment, large enough to swell out by mere imbibition, there is no reason why the imbibed plasma should not corpusculate as readily on the inside as we find it does in the matrix on the outside of the cell. There is no ground for supposing, in any case, that the several nuclei result from fission of the primary nucleus, since that, as already noted, is very often still present and increased in size. I suspect that most of the compound cells complete their development whilst still adherent, and only increase in growth subsequently. This compound cellulation is by no means peculiar to tubercle. In a more marked form, it is common in cancer; but, in very similar form, it may be met with in the cheesy secretion of the tonsils-in that of a sebaceous follicle-in healthy granulations, both in man and animals (on a horse's broken knee, for instance)—and in the plastic exudation surrounding the entozoa so constantly present in the lungs of sheep. Neither is it essential to tubercle. In a thoroughly tuberculous subject, in the midst of a thick adhesion, which connected the base of the left lung in front to the diaphragm, I found three triangular portions of true adipose tissue; and in the centre of each a distinct crude tubercle. In each of these tubercles, characteristic free corpuscles and granules α 1 b Fig. 7. Three tubercles in an adhesion between lung and diaphragm. Natural size. a. a. Lung. b. Tough, firm, pinkish, gelatious adhesion-matter. set in their matrix, formed the entire mass. There was not a compound corpuscle in any one of the three tubercles. Evidently, the course of events had been this:-The lung, having been made an abnormal fixed point, by adhesions and tuberculous consoli dation occurring at the last stage of phthisis, the diaphragm had had a tendency to drag asunder the newly-formed adhesion-matter. As this opened out into areolar tissue, fat was deposited; and into this loose fatty areolar tissue, plasma subsequently found admis sion, and corpusculated more suo into yellow tubercle. There was no epithelial surface engaged, and there were consequently no compound cells. So, likewise, when pulmo nary tubercle has become interstitial, we do not find the compound tubercle-corpuscle amongst the lung-fibres. Neither do we find it in sub-peritoneal tubercles. As Vir chow (and also, I believe, an English pathologist of equal eminence) has found the many-nucleated cells constantly in tuberculous lymphatic glands, we may perhaps infer that, although not essential to tubercle, and consequently not the crucial fact of its occurrence, this compound cellulation is still an habitual feature of tuberculization at some stage when it attacks an epithelial surface, such as that of the lungs and of the lymphatic glands. That this circumstance is due rather to the accident of place, than * My own observations have been almost limited to tuberculized bronchial and mesenteric glands. In these, I have always found some compound cells, to the kind of morbid crasis on which the disease depends, is deducible again from the fact, that the typhus-matter in Peyer's glands occasionally presents a similar phenomenon, amongst its several other points of resemblance in microscopical appearance, to the lower forms of tubercle. b. Adipose tissue. c. Tubercle, containing fat globules, free tubercle nuclei, no compound cells, and but few granules. It might be a question whether all of the compound corpuscles of tubercle do origi nate as described, acting as parent cells to endogenous nuclei. Whether in some of filmy appearance, and which are devoid of any nucleolated nucleus, the free nuclei were not the first in the field, becoming secondarily enveloped in a film of plasma whilst in contact with the wall of the air-vesicle: just as we see shrivelling blood-corpuscles become thus encased on their way to form pigment cells. We may fairly assume that the formation of the many-nucleated cells, whether it take place in one, or other, or both these ways, implies the exercise of more organizing power, and therefore the presence of greater vitality, in the parts, than does the production of free nuclei only. 4. Free Nuclei, or Tubercle-Corpuscles Proper.-These are the small single cells which make up the bulk of every variety of mature tubercle. In appearance they are irregularly round, oval, or oblong; or bean-shaped, or polyhedral, or altogether irregular; but always without sharp corners; their shape varying apparently according to their age, the kind and condition of tubercle, and the degree of pressure from close packing to which they have been subjected. They are more regular in figure in the jelly-like tubercle occasionally found in the most acute forms of phthisis, in grey miliary tubercle,. and in yellow tubercle just beginning to soften; and most rounded and plump when |