1847.] Mode of Tubercular Deposit. 447 sults of our own observations made on such preparations :-When the deposit is commencing, and when it is in such minute quantity as to escape the naked eye, the tubercular matter is seen as very small whitish masses, occupying distinctly a part or the whole of single air-cells, and presenting a resemblance to minute drops of white wax. There can be, as we have already said, no uncertainty as to its original fluid state; but we entirely agree with Vogel in asserting, that no one has seen it in that condition, for the most minute particles recognisable by the microscope are solid. As the deposit increases, and as contiguous air-cells become filled up, the vascular retia on their walls are gradually compressed and ultimately absorbed; and thus the previously isolated tubercular masses blend together, and form the larger accumulations seen by the naked eye, a process which was first distinctly traced and described by Mr. Rainey. There is. no reason to suppose that the phenomena are different in other textures, though of course they must be modified by the local circumstances. The account given by the author in the following passage differs in some important points from what is stated above, and is, we are satisfied, erroneous in affirming that the normal tissues are usually neither displaced nor altered: we refer here to such parts as blood-vessels, &c., for it is true that the elastic pulmonary membrane, in the particular case of the lung, is not entirely, if at all, destroyed. "Whenever tubercles are observed in what may be presumed to be their earliest stages, they appear solid, form a more or less dense mass, and fill up all the interstices of the elementary tissues in which they are deposited. The tissues are usually neither displaced nor altered by the tubercular matter; on the contrary, they in general retain their normal position; they are, however, as closely and perfectly invested by it, as the stones of a wall by the solidified mortar which has been applied between them. We can most readily convince ourselves of this condition by treating fine sections of tubercular deposit from the lungs with acetic acid or caustic ammonia. By means of these reagents the opaque tubercular matter is rendered transparent, and under the microscope, the enclosed portions of lung (the intersecting fibres) are perceived to be arranged amongst the tubercular matter just as in the normal state."P. 278. The microscopical characters of tubercle have been so often described that it is not necessary again to refer to them. The author, in noticing the numerous and conflicting opinions of writers respecting the chemical composition, says that nothing is at present certainly known, beyond the fact ascertained by Lehmann and repeatedly confirmed by himself, that tubercular matter consists principally of a protein-compound. In the second great class of malignant formations, Dr. Vogel includes the various forms of carcinoma-encephaloid (cellular cancer), scirrhus (fibrous cancer), melanotic (or a combination of melanosis and cancer), and colloid (gelatinous cancer). One of the leading principles connected with the whole class is, that all cancerous affections consist of a new formation, totally distinct from the normal tissues, but mixed up with a larger or smaller proportion of the original healthy structures; so that few, if any, cases of cancer are altogether malignant as to the constitution of the tumour. With respect to the individual varieties of the disease, they vary among themselves mainly according to the relative preponderance either of the new material or of the normal texture. The microscopical examination of carcinomatous growths, seems to have thrown a more clear light upon the causes of these differences, by showing that, whereas the purely cancerous matter consists essentially of cells, variously modified and mixed with a peculiar viscid fluid; the normal tissues retain their characteristic marks, and may thus be still recognised. That, in scirrhus and other similar affections, a considerable portion of the tumour is often made up either of the original structures of the body, or of fibrin effused by common inflammatory action, has long been known: and herein is to be found the explanation of those cases, which from time to time are adduced as proofs of the possibility of curing these hitherto unmanageable diseases; the fact being, that the absorbent action is, in these instances, excited, and the healthy tissues, or the inflammatory deposits being removed, it is erroneously affirmed that the special and essential epigenesis is eradicated. It is not necessary to give the author's account of the microscopic elements of cancer, as it does not contain any novel information. The cancerous matter, he believes, as in the case of tubercle, is effused in a liquid form, and so becomes infiltrated into the tissue of the affected part, undergoing subsequently a process of coagulation. The cancerous matter occurs between original elementary parts of the parent tissue, and occupies, more or less perfectly, all the interstices. A slight infiltration of cancer in a tissue, frequently escapes the observation of the unaided eye, and can only be detected by careful microscopic examination-as, for instance, in fatty tissues. When the interstices are not thoroughly filled, and the cancerous deposit is soft, the parent-tissue, at least in the first stage, is comparatively little injured. If, on the other hand, the infiltration is complete and the cancerous deposit very firm and solid, then the elements of the tissue become compressed, appearing to be blended with the deposit into a homogeneous mass, and gradually become atrophied and disappear. This disappearance of the elements of the tissues by atrophy and resorption, which is peculiar to the first stage of cancer, previous to softening, must be clearly distinguished from the destruction of the entangled tissue, which is dependant on the softening of cancer, and of which we shall speak presently.”—P. 301–2. The vascularity of carcinomatous tumours varies, as it is well known, in different forms of the affection; in some cases, blood-vessels are almost or entirely absent; whilst in other instances, and especially in the soft varieties, as fungus hæmatodes, they are so numerous that, when ulceration has taken place, the exposed surface bleeds on the slightest contact. The general views of the author, as to the nature and progress of these affections, may be gathered from the following extract, with which we must close our notice of this subject : 66 Simultaneously with the process of development, the cancerous tumour undergoes other changes; it increases to such a degree, that from a very limited origin it often becomes distributed over a large space, occupying one or even several organs. This enlargement is undoubtedly dependant on the cellular structure of the cancer, and probably also on the fibres acting upon the nutrient fluid in the neighbouring parts, in accordance with the law of analogous formation. The increase of the cancerous cells is forwarded by the circumstance that many of them act the part of parent-cells, and contain in their interior young cells, which in all probability are capable of a similar mode of increase. More 1847.] •Development of Cancer. 449 over the numerous cytoblasts frequently observed in a cell, probably all become themselves developed into distinct cells. With these facts before us, there is clearly no limit to the increase of cancer-cells, neither is there any necessity for regarding them as distinct organisms similar to the lowest fungi and algæ. It is clear, however, that the fibres and the vessels (if any are present) cannot be increased by means of the cancer-cells; in all probability the increase of the fibres-and in fibrous cancer such an increase undoubtedly occurs-is dependant upon the influence of the pre-existing fibres, just as is the case in the growth of pure fibrous tumours. The innate capacity for augmentation possessed by cancer, is very energetic, and forms an essential distinction between cancerous tumours and scrofulous depositions; for, in the latter, this capacity is either altogether absent, or only present to a very slight degree. Hence the growth of cancer is most rapid when an increased cytoblastema is yielded to it from any source, as, for instance, from inflammatory exudation, especially from fibrinous dropsy in the adjacent parts. It always increases on the supervention of softening and ichorous discharge, in consequence of the irritation to which these processes give rise in the surrounding parts. The exudation thus yielded by the neighbouring hyperamic parts is converted into cancerous matter, and hence cancer is not, as is frequently the case with tubercle, separated from the surrounding parts by granular cells or pus, nor is it retarded in its growth by a line of demarcation. The newly-formed cancerous matter goes through precisely the same course of development as the original; proceeding of necessity to softening. In some cases, we find the peripheral portion of the cancerous matter, and the surrounding parts contending, as it were, for the cytoblastema, and sharing it between them. There are formed, as inay be observed in cancerous ulceration, fungoid and extremely vascular granulations; but these are always so infiltrated with cancerous matter, that, after a very brief existence, they soften and become disintegrated, never contributing to the formation of persistent tissues."-P. 304-5-6. In the 8th Chapter, Dr. Vogel gives a brief but interesting summary of the parasites, vegetable and animal, or, as he terms them, "independent organisms," which infest the human body—a subject of considerable importance in practical medicine, and which has, in late years, attracted a large share of the attention of the most eminent zoologists. In many instances, it is no easy matter to account for, or even to conceive of, the origin of entozoa, and their entrance into the organs where they are met with; more especially if we adopt, as we are inclined to do, the definition of Vogel, who limits "the acceptation of parasites to those organic structures whose germs have penetrated into the organism from without." In the case of the entozoa, which have their habitat either in those cavities of the body that have a direct external communication, such as the various intestinal worms; or which are domiciled in organs having an indirect connection with the exterior, as the distoma hepaticum in the gallbladder, and even the formidable strongylus gigas lodged in the kidney; in these and similar cases, although the origin from without may not be very obvious, still it may be comprehended. But what is to be said of those parasites which exist in the parenchyma of solid organs, or in cavities closed in on every side How, for instance, does the trichina spiralis find its way into the very sheath (sarcolemma) of the primary muscular fasciculus, or the cysticercus into the brain or chamber of the eye? The difficulty of explaining these phenomena by the ordinary mode of reproduction, has led to the idea of spontaneous generation; a doctrine which, although from time to time still advocated, is opposed to every real advance in the sci ence of embryology. In the following extract the author, after setting forth the arguments that have been adduced in favour of this theory, thus opposes them. * * * "Let us now consult experience for materials in order to reply to this question. We find that in all cases where opportunity has been afforded of tracing, by direct observation, the origin of an organism, it has taken place by propagation; whilst, on the contrary, not a solitary unexceptionable observation of a spontaneous origin exists in the records of natural history. Analogy is, therefore, completely in favour of the view that propagation is the only manner in which existing organisms are engendered. The objections which have been urged against this view, and the arguments which have been adduced in favour of a spontaneous production of parasites, rest chiefly on the ground that in many cases the origin of these organisms, by means of propagation, is inexplicable; and is, therefore, held to be impossible. But it is overlooked that the assumption of their spontaneous origin is in reality merely a formal explanation, which leaves us completely in the dark respecting the true reasons and conditions of their production. Moreover, many of these reasons have latterly become invalidated by the progress of knowledge, since not merely the possibility, but also the reality of their propagation to other organisms, and the inducing conditions, have been demonstrated in various parasites; and although in this respect at present much appears mysterious, yet the numerous experiences of latter years must raise a hope in every unbiassed observer, that the further advancement of knowledge will clear up the obscurity which at present envelops this province, and will establish the origin of all parasites by propagation, to the exclusion of spontaneous origin."-P. 424. It follows, from this view of the question, that parasites are never a true product of disease, and cannot therefore originate from degenerated particles of the body, depraved secretions, &c.: a position which does not, however, invalidate the commonly-received and firmly-established opinion, that certain morbid changes of the body favour the development of entozoa by furnishing those conditions under which alone these animals can exist. "Thus, for example, vegetable parasites (fungi) do not in general develop themselves upon mucous membranes, until, by morbid processes, a deposit of coagulated fibrin, which serves as a bed, has become prepared for them, and until this exudation has passed into a state of putrid decomposition. An abundant secretion of mucus favours the development of worms which have entered the intestinal canal from without. Some states of the organism, on the contrary, disqualify it as a habitation for parasites. Thus, most of the entozoa in the intestinal canal are expelled by increased peristaltic action; some fluids of the body, as bile, urine, gastric juice, and some medicines, prove deleterious, and indeed fatal, to some of them; inflammation, or at least suppuration, may injure, and even destroy them." -P. 425. A part of the mystery still involving this enquiry has been cleared away by the admirable researches of Steenstrup, which were noticed in a former number of this Journal (see Med.-Chir. Rev., July, 1846, p. 22). The leading fact therein demonstrated, that there are, namely, in many classes, and especially among the entozoa, animals which act as nurses, giving birth to new beings without being truly prolific, elucidates many points in the reproductive process of parasites. The generation of the guineaworm (filaria medinensis) is so remarkable as to have given rise to some 1847.] On Malformations. 451 doubt as to its real character: "they are viviparous, and contain in their interior such a prodigious quantity of young that some maintain the worm is not an animal at all, but a membranous sheath filled with small worms. It is further peculiar, although the existence of a male is known, that as yet only female filaria have been found in the human body. It may then be asked-do females alone, while still young but after their impregnation, enter the body, because they there find conditions favourable to their further development? (L. c., p. 457.) All these circumstances seem to indicate a resemblance to some of the stages described and depicted by Steenstrup; but it is proper to remark that the nematoidea have not presented to that careful observer any distinct evidence of alternate generations, so that further information is required upon this interesting question. Among the parasitic animals one of the most curious is the acarus folliculorum, belonging to the arachnida, discovered by Simon of Berlin and since described by other observers. It is sometimes spoken of as occurring so frequently that its presence can scarcely be regarded as abnormal. We believe, however, that there is some mistake in this statement: at all events it is no easy matter to procure specimens for the microscope, a circumstance difficult to reconcile with some of the accounts that have been published. According to the author, the a. folliculorum very frequently exists in the hair glands of the human subject, on the nose, upper lip, and the glands of the beard, being sometimes solitary, whilst at other times ten or more are found in a single gland. There is no subject on which the comprehensive and accurate researches of modern anatomy have thrown so much light, as that relating to malformations. The older observers, troubling themselves but little with the general laws of organization, rested satisfied, like their brethren of the geological school, with regarding all deviations from the ordinary course of things as lusus naturæ. Speaking of these vitia prima conformationis, Bischoff, in his interesting sketch, says justly," for a long time they were rather objects of affright and aversion, of superstition and of curiosity, than of scientific investigation." It is, however, certain that by far the greater number of congenital malformations are susceptible of explanation according to the known principles of development and of nutrition; and, when closely scrutinized, notwithstanding the wide departure from the normal process they may seem to present, they fall into definite classes recognisable by the embryologist as belonging to certain phases in the development of the foetus. So much, indeed, is this the case, that the study of malformations and of developmental anatomy mutually illustrate each other; and it is not too much to affirm that the former, as a philosophical investigation, could never have been successfully cultivated without the aid and the elucidations of the latter. These considerations will enable us to appreciate the definition which Bischoff has adopted, as best expressing the true nature of these deviations from the normal process of growth. "A malformation is then that deviation of form, affecting either an organism or an organ, which is so intimately mixed up with the primitive mode of origin and of development, * Wagner's Handwörterbuch der Physiologie. Band I. p. 860. |