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histological and functional character of an organ. Every inflammation with free exudation in general affords a certain degree of relief to the part; it conveys away from it a great part of the noxious matters with which it is clogged, and the part therefore appears comparatively to suffer much less than that which is the seat of a parenchymatous disease.

LECTURE XVIII.

APRIL 21, 1858. NORMAL AND PATHOLOGICAL NEW-FORMATION.

The theory of continuous development in opposition to the blastema- and exudation-theory.—Connective tissue and its equivalents as the most general germ-store of new-formations.—Correspondence between embryonic and pathological new-formation.—Cell-division as the most general startingpoint of new formations.

Endogenous formation.—Physalides.—Brood-cavities.

Different tendencies of new-formations.—Hyperplasia, direct and indirect.— Heteroplasia. — Pathological formative cells. — Difference in their size and in the time required for their formation.

Description of the development of bone as a model-formation.—Difference between formation and transformation.—Fresh and growing, in opposition to macerated, bone.—Nature of medullary tissue.—Growth in length of tubular [long] bones; proliferation of cartilage.—Formation of marrow as a transformation of tissue; red and yellow, normal and inflammatory marrow. — Osseous tissue, calcified cartilage, osteoid tissue. — Bone-territories: caries, degenerative ostitis.—Granulations in bone.—Suppuration of bone. — Maturation of pus. — Ossification of marrow. — Growth of long bones in thickness: structure and proliferation of the periosteum.

Granulations as analogous to the medulla of bones, and as the starting-point of all heteroplastic development.

Gentlemen,—I propose to-day, in illustration of formative irritation, to portray to you the most important features in the history of pathological new-formations, for a knowledge of these will throw light upon a series of events which present themselves both in the more complicated formation of tumours, and in the more simple inflammatory irritative processes. That I at present entirely reject the blastema doctrine in its original form, you have no doubt already gathered from the previous lectures. In its place I have put the very simple doctrine of the continuous development of tissues out of one another. The chief point therefore in individual cases is to determine the particular manner in which the various tissues arise, and by means of definite examples to make oneself acquainted with all the different directions which it is possible this development may follow.

My first observations, in consequence of which I began to entertain doubts with respect to the prevailing blastema and exudation doctrine—as to how far, namely, new-formations could be derived from this source—date from researches of mine on tubercle) I found namely that a series of tubercular deposits in different organs, especially in the lymphatic glands, the membranes of the brain and the lungs, never at any time exhibited a discernible exudation, but always, during the whole course of their development, presented organized elements, without its ever being possible to observe either in them, or before they existed, any stage in which amorphous, shapeless matter was present. As long as eight years ago I discerned that the development which takes place in the lymphatic glands upon the occurrence of the well-known scrofulous changes, begins in such a way, that the first conditions met with entirely correspond to those which in other instances are designated by the name of hypertrophy; for nuclei and cells are found in great abundance, though they afterwards break up and directly supply the material for the final accumulation of cheesy substance. The view which I derived from these investigations of mine, namely, that a tissue undergoing TYPHOUS MATTER. THE CONNECTIVE-TISSUES. 397

1 See a paper on tuberculosis and its relations to inflammation, scrofulosis and typhoid fever. Vcrhandlungen der phvsikalisch-medic. Gescllscbaft zu Wiirzburg, 1850, vol. i, p. 81.

hypertrophy may supply a completely abnormal, diseased product, appeared to me all the more significant, because I had simultaneously detected an altogether similar series of developmental changes whilst examining an entirely different body, namely the so-called typhous matter (Typhusmasse). At that time the view of the Vienna school had been universally adopted, that, in the different typhous processes, an exudation of an albuminous nature and soft, medullary character filled the parts, and that thereby swellings of a medullary appearance were produced. But whether the typhous matter be examined in the lymphatic glands of the mesentery, or round about the follicles of Peyer's patches, no exudation capable of organization is at any time met with, but always a directly continuous development from the pre-existing cellular elements of the glands, the follicles and the connective tissue, to the typhous matter. These observations were of course as yet insufficient to justify me in setting about effecting a general change in the existing doctrine, because we see organic elements arise at numberless points, where at that time at least cellular elements were altogether unknown to exist as normal constituents, and there was therefore scarcely any other explanation possible than that new germs were formed by a kind of generatio aequivoca (spontaneous generation) out of the mass of blastema. The only places, besides the glands, where such a development arising out of previously existing elements might have been inferred with some degree of probability to take place, were the surfaces of the body with their epithelial elements. Then it was, that my investigations into the nature of the connective tissues, with which I have already so much plagued you, proved entirely decisive. From the moment that I was able to maintain that there was scarcely any part of the body which did not possess cellular elements—that I could shew that hone-corpuscles were real cells, and that connective tissue in different places contained, now a larger, now a smaller, number of really cellular elements—from that moment germs in abundance were supplied from which new tissues might possibly be developed. In fact, the more the number of observers increased, the more distinctly was it shewn, that by far the greater number of the new-formations which arise in the body proceed from connective tissue and its equivalents. From this rule comparatively few pathological new-formations are excepted, and these belong on the one hand to the class of epithelial formations, and on the other are connected with the more highly organized tissues of a specific, animal (p. 28) nature, for example, the vessels. We may therefore, with trifling restrictions, substitute for the plastic lymph, the blastema of the earlier, the exudation of the later writers, connective tissue with its equivalents as the common stock of germs (Keimstock) of the body, and directly trace to it as the general source the development of new-formations.

If we take a definite internal organ, for example, the brain or the liver, it was scarcely possible, as long as people saw nothing more than nervous matter in the brain, and admitted the existence of nothing more than vessels and hepatic cells in the liver, to imagine the occurrence of-a new-formation in them without the intervention of a special formative matter. For it was of course easy to convince oneself that new-formations do not in the liver usually proceed from the hepatic cells or the vessels. And that in the substance of the brain, the nerves as such do not give rise to new-formations, has been known ever since the microscope has been employed, for since that time it has been known that medullary cancers are not due to the proliferation of nervous matter, but consist of cellular elements of another kind. In fact, the body appears to us at the present day, as Reichert was the first to note, to be made up of a more or less continuous mass of connective tissue

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