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been so termed which commences quite at the surface of the internal arterial coat. When the matter began to be examined more minutely, and fatty particles (Fig. 113) were found at very different points in the walls of the vessel, both when atheroma was, and was not, present—when at last the conviction was obtained, that the process of fatty degeneration was always the same and was identical with the atheromatous change, it became the custom to unite all the forms of the fatty degeneration of arteries under the designation atheroma. Gradually, people even came to speak of an atheromatous change in vessels, that only possessed a single coat, for in them too we meet with fatty processes.

At all times there have moreover been observers who regarded the ossification of vessels as a change belonging to the same category as atheroma. Haller and Crell believed that the ossification proceeded from the atheromatous matter, and that this was a juice which, like that exuding under the periosteum of bone, was capable of generating plates of bone out of itself. Afterwards it was recognized that atheromasia and ossification were two parallel processes, which, however, might be referred to a common origin. Now it would, I think, have been logical, if in the next place an understanding had been come to as to what this origin was, from which the atheromatous change and the ossification proceeded. But, instead of this, the track of fatty degeneration was pursued, and thus the atheromatous process was extended to a number of vessels, in which, on account of the thinness and the simple structure of their walls, the formation of any depot, which could really be compared to an atheromatous cyst of the skin, was altogether impossible.

The state of the matter here also is more or less very simply this, that two processes must be distinguished in the vessels, which are very analogous in their ultimate results; first, the simple fatty metamorphosis, which sets in THE ATHEROMATOUS PROCESS. 355

without any discoverable preliminary stage, and in which the existing histological elements pass directly into a state of fatty degeneration and are destroyed, so that a larger or smaller proportion of the constituents of the walls of the vessel perishes; and, in the next place, a second series of changes, in which we can distinguish a stage of irritation preceding the fatty metamorphosis, comparable to the stage of swelling, cloudiness, and enlargement which we see in other inflamed parts. I have therefore felt no hesitation in siding with the old view in this matter, and in admitting an inflammation of the inner arterial coat to be the starting point of the so-called atheromatous degeneration; and I have moreover endeavoured to shew that this kind of inflammatory affection of the arterial coat, is in point of fact exactly the same as what is universally termed endocarditis, when it occurs in the parietes of the heart. There is no other difference between the two processes than that the one more frequently runs an acute, the other a chronic, course.

By the establishment of this distinction between the different processes which occur in the arteries, the difference of the course they pursue is at once accounted for. Last time I laid an artery before you, on the inner surface of which you saw little whitish patches, which were due to simple fatty transformation. To-day you see very extensive patches in the aorta, in which the atheromatous change has taken place. But, as is wont to be the case in changes of this kind, in addition to the specific transformation attendant upon the chronic inflammatory processes going on in the deeper parts, you find on the surface also a simply fatty change, so that we have the two processes occurring together. If now we examine atheromasia a little more minutely, for example in the aorta, where the process is the most common, the first thing we see present itself at the spot where the irritation has taken place, is a swelling of larger or smaller size and not unfrequently so large as to form a really hump-like projection (Buckel) above the level of the internal surface. These projections are distinguished from the neighbouring parts by their translucent, cornea-like appearance. In their deeper parts they look more opaque. When the change has lasted for a certain time, the first further metamorphoses do not shew themselves at the surface, but just where the internal comes into contact with the middle, coat, as has been very well described by the old writers. How often have they distinctly contended that the internal coat could be stripped off over the affected spot! Hence arose the description of Haller, that the pultaceous, atheromatous mass lay in a closed cavity, as it were a little cystic tumour between the internal

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Fig. 116. Vertical section through the walls of the aorta at a sclerotic part in which atheromatous matter is already in the course of formation. m m. Middle coat, i i i", internal coat. At 8 the highest point of the sclerotic part where it projects into the cavity of the vessel, i the innermost layer of the internal coat running over the whole d£pot, i' the proliferating, sclerosing layer, preparing for fatty degeneration, i" the layer immediately adjoining the middle coat which has already undergone fatty degeneration, and at e, e, is in process of direct softening.

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and middle coat. The only mistake was, that the tumour was regarded as a distinct body separable from the coats of the vessels. It is rather the internal coat itself which without any well defined limits passes into a state of degeneration within the prominent spot. The farther this degeneration advances, the more distinctly does an enclosed collection arise out of the destruction of the deepest layers of the internal coat; and at last it may be that the swelling fluctuates, and that upon cutting into it the pultaceous matter is evacuated, like the pus, when an abscess is cut into. Now if the mass be examined which is present at the close of this process, numerous plates of cholestearine are seen, which display themselves even to the naked eye as glistening lamellae; large rhombic tablets, which lie together in large numbers, side by side, or covering one another, and altogether produce a glittering reflection. In addition to these plates, we find under the microscope black-looking granule-globules, in which the individual fat-granules are at first very minute. These globules are often present in very large quantity; some of them are seen, breaking up, and falling to pieces, particles of them swimming about, as in milk. Besides these there are amorphous fragments of tissue of larger or smaller size which still cohere, and are rather due to the softening of the rest of the substance

Fig. 117. The pultaceous atheromatous matter from a patch in the aorta, a a'. Fluid fat, the product of the fatty metamorphosis of the cells of the internal coat (a), which become transformed into granule-globules (a' a'), then disintegrate and set free large and small drops of oil (fatty debris), b. Amorphous, granularlywrinklcd flakes of tissue softened and swollen by imbibition, e, d. Crystals of cholestearine; c large rhombic plates, c, e fine rhombic needles. 300 diameters.

Fie. 117.

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of the tissue which has not undergone fatty degeneration; and in them heaps of granules are here and there imbedded. It is these three constituents together, the cholestearine, the granule-cells and fat-granules, and finally the large lumps of half-softened substance, which give the atheromatous matter its pultaccous character, and really produce a certain degree of resemblance to the contents of a pultaceous [sebaceous, epidermic] cyst (Grutzbcutel) of the skin. With regard to the cholestearine, it is by no means a specific product, appertaining to this kind of fatty transformation alone. On the contrary, we see in every case, where fatty products remain stagnant for a considerable time within a closed cavity in which but little interchange of matter can go on, that the fat sets free cholestearine. All the masses of fat which we meet with in the body contain a certain quantity of cholestearine in combination. As to whether the cholestearine which is set free had already previously existed, or whether a real new formation of it takes place in the parts, not a word can as yet be said, inasmuch as no chemical fact has, it is well known, been made out, which throws any light upon the manner in which the formation of cholestearine is effected, or upon the substances, out of which cholestearine may be formed. This much, however, we must hold fast, that cholestearine is a product set free at a late period from stagnating, and, particularly, from fatty matters.

I may take this opportunity to mention the reaction of cholestearine with iodine and sulphuric acid, which has recently become important, and is similar to that which we have already (p. 5) considered when speaking of the cellulose of plants. When, namely, iodine alone is added to cholestearine, no change is seen any more than in cellulose, under similar circumstances; but when, on the other hand, sulphuric acid is applied to the iodized mass of cholestearine, its plates become coloured and assume, particularly at first, a brilliant indigo-blue tint, which gradually passes into a yellowish

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