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a very marked malignity, for not only are they liable to recur at their original site, but they also reproduce themselves in distant parts. In many cases nearly all the organs of the body are metastatically filled with masses of cancroid. Again, if you attempt to distinguish cancroid growths from real cancer by the epithelial structure of their elements, you will herein too give yourselves trouble in vain. Cancer proper has also elements of an epithelial character,
and you need only turn to those parts of the body, where the epithelial cells are irregularly developed, as for example, in the urinary passages (Fig. 15), and you will meet with the same curious bodies, provided with large nuclei and nucleoli, which are described as the specific, polymorphous cells of cancer. Cancer, cancroid or epithelioma, pearly tumours or cholesteatoma, nay perhaps the dermoid growths which produce hairs, teeth, and sebaceous glands, and so frequently occur in the ovary—all these are formations in which there is a pathological production of epithelial cells, but they constitute a graduated series of different kinds, which extend from those which are entirely local, and, in the usual meaning of the word, perfectly benignant, to the extremest malignity. The mere form of the cells which compose a structure, is of no decisive value. Cancer is not malignant because it contains heterologous cells, nor cancroid benignant because its cells are homologous—they are both malignant, and their malignity only differs in degree.
Fig. 142. Various, polymorphous cancer-cells, some of them in a state of fatty degeneration, two with multiplication of nuclei. 300 diameters.
The forms which yield dry, juiceless masses, are relatively benignant. Those which produce succulent tissues have always more or less a malignant character (p. 217). The pearly tumour, for example, yields perfectly dry epithelial masses, almost without a trace of moisture, and it only infects locally. Cancroid remains for a very long time local, so that the nearest lymphatic glands often do not become affected unti l after the lapse of years, and then again the process is for a long time confined to the disease of the lymphatic glands, so that a general outbreak of the disease in all parts of the body does not take place until late, and only in rare instances. In cancer proper the local progress is often very rapid and the disease early becomes general; a cure, even for a short time, is so rare, that in France the complete incurability of cancer properly so called has been asserted and maintained with success.
Fig. 143. Section through a cancroid of the orbit. Large epidermic globules (pearls), laminated after the manner of an onion, in a closely packed mass of cells, which have partly the character of epidermis, partly that of the rete Malpighii. 150 diameters.
Among the formations also which are analogous to the ordinary connective tissues, and are therefore apparently perfectly homologous and benignant, the succulent ones prove to be much more capable of communicating infection than the dry ones. A myxoma which has always a good deal of fluid about it, is at all times a suspicious tumour, and, in proportion to the quantity of juice it contains, is its liability to recur. Cartilaginous tumours (Enchondromata) which were formerly described as unquestionably benignant, sometimes occur in soft and rather gelatinous forms, which may occasion just such internal metastases as cancer properly so called. Even connective-tissue1 (fibrous) tumours become, under certain circumstances, richer in cells and enlarge, whilst their interstitial connective tissue becomes more succulent, nay in many cases disappears so completely, that at last scarcely anything but cellular elements remain. This is the kind of tumour which, according to my opinion, ought to be designated by the old name of Sarcoma. These sarcomata are frequently, indeed, benignant, still they do not unfrequently recur, like epithelial cancer, at their original site, whilst under certain circumstances they appear
Fig. 144. Diagrammatic representation of the development of sarcoma, as it may very well be seen in sarcoma of the breast. 350 diameters.
1 Fibrous tissue is dense connective tissue. It is not a special tissue, but only a form of connective tissue. Periosteum, perichondrium, tendons &c, all of them consist of connective tissue, in which, however, the cells have in part become converted into elastic fibres and networks. In Germany indeed connective
TUMOURS OF PLANTS. 487
secondarily in the lymphatic glands, and in many cases occur throughout the whole body metastatically to such an extent, that scarcely any organ is spared by them.
In the case of all these formations, every one of which corresponds more or less completely to a normal tissue, investigations ought not to be conducted with a view to determine whether they have a physiological type, or whether they bear a specific stamp impressed upon them; our final decision depends upon the answer to the question, whether they arise at a spot to which they belong, or not, and whether they produce a fluid, which, when brought into contact with the neighbouring parts, may there exercise an unfavourable, contagious or irritative influence.
It is with these formations as with vegetable ones. The nerves and vessels have not the slightest direct influence. They are only of importance so far as they determine the greater or less abundance of supply; they are altogether unable to impel to the development of tumours, to produce them or to modify them in a direct manner. A pathological tumour in man forms in exactly the same way that a swelling on a tree does, whether on the bark, or on the surface of the trunk or a leaf, where any pathological irritation has occurred. The gall-nut which arises in consequence of the puncture of an insect, the tuberous swellings which mark the spots on a tree where a bough has been cut off, and the wall-like elevation which forms round the border of the wounded surface produced by cutting down a tree, and which ultimately covers in the surface—all of them depend upon a proliferation of cells just as abundant and often just as rapid as that which we perceive in a tumour of a proliferating part of the human body. The pathological irritation acts in both cases precisely in the
(cellular) tissue has ever since the time of Treviranus (1835) been divided into formed and formless, the former including tendons, fascia, ligaments, &c.—From a MS. note by the Author.
same manner; the processes in plants conform entirely to the same type, and just as little as a tree produces on its bark or leaves cells of a kind, which it could not bring forth at other times, just as little does the animal body do this.
But if you consider the history of a vegetable tumour, you will see there also that it is above all the diseased spots which become unusually rich in specific constituents, and absorb and store up the peculiar substances which the tree produces, in more than average quantity. The vegetable cells which form on an oak-leaf round the puncture made by an insect contain much more tannic acid than any other part of the tree. The tumour-cells which form with such exuberance in a pine at the spot where an insect has buried itself in the young trunk, are stuffed completely full of resin. The peculiar formative energy which is developed at these spots, occasions also an unusually abundant accumulation of juices. There is no need of any nerves or vessels to instigate the cells to an increased absorption of matter. It is by their own action—by means of the attraction which they exercise upon the neighbouring fluids—that they draw in the most serviceable materials. The great importance, which a knowledge of botany possesses for the pathologist also, lies in this—that it enables him to discover in all these processes the existence of an inward correspondence in the whole series of vital phenomena, and to shew how the lowest formations may serve to explain the history of the most perfect and complex parts.
I have in the course of these lectures, gentlemen, developed to you as completely as it was possible for me here to do, the principles by means of which alone it is, according to my experience, possible to come to any correct decision in the case of pathological processes. I heartily thank you for the lively interest which you have testified