termine the question affirmatively, for these authors state that actual idiopathic suppuration does occur in the artery.

The spontaneous coagulation of the blood in the arteries is not, however, the result of inflammatory action only. It may occur in consequence of a low ataxic condition, which does not permit the vital powers to resist the chemical tendencies that normally ought not to come into play until after death. This spontaneous coagulation is especially met with in the pulmonary arteries, where the occurrence of the inflammatory symptoms has, as yet, not been met with. Mr. Paget,' in describing a case of the kind, says, that nearly all the branches beyond the primary divisions of the pulmonary artery contained clots of blood, which, from a comparison with those found in tied arteries, he judged to be from three to ten days old. The clots did not commonly extend continuously from any large branch of the pulmonary artery into many of its successively subordinate divisions, no branch of the pulmonary artery less than half a line in diameter appeared to contain any of these clots, and the pulmonary veins were healthy and empty. The case under consideration proves that a large portion of the pulmonary circulation may be arrested for a considerable period without immediate danger to life, a circumstance explained by Mr. Paget, by assuming a retardation of the circulation in the systemic vessels, in order to allow the quantity traversing them in a given time to be equal to the reduced quantity which in the same time traverses the lungs. In order to keep up the necessary balance, the systemic circulation is as much less rapid than the remaining pulmonary circulation is more rapid than before the obstruction. took place.

The formation of a coagulum in the artery does not necessarily block up the entire passage, but may leave a central opening by which the circulation yet continues to be carried on. But after the formation of the clot, it in its turn undergoes various changes; it may become absorbed, or it softens or breaks up into granular matter, and is carried into the capillary circulation, or it is capable of organization, and we then find in it a network of fine bloodvessels. The last point serves to elucidate the observations of the passage of an artery occasionally seen in old coagula formed after the application of a ligature. Lobstein, as we are informed by Hasse, met with an arterial vessel of the caliber of the stylo-mastoid artery running lengthwise through the femoral artery obliterated two years previously by tying. Blandin and Barth have met with analogous instances, to which may be added those cases in which, after the complete obliteration of arteries by ligature, new vessels have been found shooting from their extremities. The general infection of the blood from breaking up of arterial coagula, is a very rare occurrence; a circumstance which establishes a marked distinction between arterial and venous disease; it is referred by Rokitansky to the greater susceptibility of the arterial blood for taking up inflammatory products, which speedily give rise to coagulation and obturation of the vessel, and to the circumstance that their reaction in the arterial

See Mr. Paget on obstructions in the Pulmonary Arteries, Medico-Chirurgical Transact., vol. xxviii. p. 533.

current, being exhausted towards the capillaries in ordinary cases, hinders the general infection of the blood beyond the limits of those vessels.

CHRONIC ARTERITIS.

With regard to chronic arteritis, the opinions of writers are yet more divided than in reference to the acute form. The same difficulties in determining the relation of cause or effect in this subject has been felt by most of the writers on the subject, and have not yet met their complete solution. The older authors attributed the appearances of chronic arteritis to syphilitic taint or mercurial poisoning; some of the more recent, among whom we may mention Corvisart, have held a similar opinion, and Hodgson' supports it on the ground that he has observed aneurism, and those organic alterations which generally attend the formation of aneurism, to prevail in subjects that have suffered from venereal disease, and who have taken large quantities of mercury.

While the majority of authors are of opinion that fibrinous deposit, atheroma, ulceration, ossification, and aneurism are the result of a chronic inflammatory process, Hasse absolutely denies its primary existence, and only admits its occasional occurrence as a secondary effect of the degenerative processes alluded to. On the other hand, Rokitansky looks upon chronic inflammation of the arteries as an essential constituent of morbid deposits on the inner coats of the vessel, and its metamorphoses, but is of opinion that it is primarily manifested in the cellular sheath of the arteries, where it produces hypertrophy, thickening, and condensation, followed by a secondary disturbing action upon the normal relation of the inner arterial coats, the fibrous and true lining membrane. It is very certain, however, that we very rarely meet with traces of this superficial cellular inflammation of arteries, except as a result of their implication in morbid processes of the surrounding tissues, as in phlegmonous erysipelas, or in tubercular destruction of the parts; while we constantly have occasion to examine deposits underneath the lining membrane in their incipient stages. Here, we almost uniformly find an accompanying tumefaction and reddening, affecting the entire thickness of the inner coat, which is distinctly perceptible on making a section of the artery. This change is accompanied by a puckering and plicated condition, and extends to a greater or less distance beyond the circumference of the deposit. The reddening, though persistent, is not due to the formation of new vessels; the microscope fails to detect them. The softening, which we find to be a common result of inflammatory action, affects the entire caliber of the artery, and in that case may give rise to a uniform dilatation, or to what has been termed true aneurism. The deposit which invariably takes place in the first instance, between the middle and internal coats, is of a yellowish tinge, and forms slight elevations, in circumscribed dots or patches; as the disease advances, these * coalesce, and may thus affect the vessel to a considerable extent. We are not prepared to state, nor are we of opinion, that the chemical

Essai sur les Maladies du Cœur, p. 819.

On the Arteries, p. 9.

character of the primary deposit is in all cases identical; this would not be in accordance with what we know of the elimination of morbid constituents of the blood. But there is no doubt that in a majority of cases the atheromic deposit is a secondary fatty degeneration of fibrin. We are inclined to suggest that the more purely inflammatory the cause

Incipient atheroma and fatty degeneration of an iliac taken from an aged female. The lining membrane is much puckered, owing to the irregular deposit of fibrin between it and the middle coat. A. Naked-eye view of the artery. B. Microscopic appearance of the fibrinous deposit, dotted with oil-molecules. c. A longitudinal section of the artery taken between *-*; j, the inner coat with subjacent deposit; m, middle coat unaltered; o, the external coat.

of the disease, the more presumption there is of a fibrinous deposit in the first instance. The fibrin seen by the naked eye presents little or no distinction from actual atheroma; but, on examination by the microscope, we see the delicate fibrillæ characteristic of this matter; and we also detect in it glistening particles of oil, which show the transition to atheroma. The fibrin is itself deposited in distinct lamine, which may

easily be separated from one another in the plane of the vascular coats; there is no arrest of the coat investing it on the minor surface of the artery, but this may be peeled off to an indefinite extent beyond the

Fig. 153.

deposit, showing that in the earlier stage there is no solution of continuity of the lining membrane, a point of some importance in reference to the doctrine expounded by Rokitansky. This author, who treats of the diseases in question as a new formation of the lining membrane from the blood, does not appear to have recognized this form of deposit, which we have delineated, and which is clearly subjacent to the inner coat. Dr. Hope, who does not, however, appear to have confirmed his view by a microscopic examination, looks upon the fibrinous deposit as the first stage of the metamorphosis; and, until further investigations confirm the views of the Viennese Professor, we adhere to the doctrine just adverted to, in preference to what we cannot but regard as a forced explanation. It is, however, but due to the high reputation of Professor Rokitansky, that we should allow him to speak for himself in this question, in order that further investigation may determine the point; he says:1 "The most frequent form of disease affecting the arteries is an excessive formation and deposition of the lining membrane of the artery, derived from the mass of the blood, and at the same time constituting hypertrophy of this membrane. In a highly developed form of this affection, we find the inner surface of a large artery, as the aorta, covered with a foreign substance, spread over it at separate points or in large patches, and forming a stratum varying in thickness, by which the inner surface of the vessel is commonly rendered uneven; this substance is, in some places, either grayish, grayish-white, faded and translucent, or, in others, milky white, opaque, and similar to coagulated albumen; in some rare instances it is colored by the imbibition of hæmatin, over various extents of surface. Its free surface is at the same time smooth and shining, or dull, and, as it were, wrinkled. It is soft, moist, and succulent in the translucent parts, and dense, dry, tough, and elastic in the more opaque portions; resembling a cartilage or fibro-cartilage, with which it is usually compared, and for which it is still occasionally mistaken. In the latter condition, it adheres internally to the circular fibrous coat." Hasse considers that when chronic arteritis is induced by degenerative processes, we find a deep, dingy, brownish-red color, extending to the middle tunic, a densely injected state of the vasa vasorum of the cellular sheath, and a deposition of plastic material in the caliber of the vessel; these deposits accumulating in masses, adhering to the arterial parietes, and consisting of imbricated layers.

Atheroma from old patch.

We occasionally find a general thinning of the coats of an artery without any appreciable change in their composition, in the same way as we also find an hypertrophic condition of the same character. In either case it appears generally to be at the expense of the middle fibrous coat. But, in the great majority of instances, we shall, on careful examination, succeed in detecting some existing, or some ante

Pathol. Anat. vol. iv. p. 261. Sydenh. Society's Ed.

The

cedent, morbid deposit to which the condition is attributable. most important of these is what is commonly called the atheromatous process.

1

ATHEROMA.

Atheroma, or, as it has also been called by Baillie and others, steatoma of the arteries, is not, as we have already seen, necessarily a soft, pulpy deposit; but appears, in the first instance, as a series of fibrinous layers subjacent to the inner coat of the artery, formed by a process

analogous to secretion from the blood. Small oil-globules are early seen in the fibrin, and in the course of time the latter may become completely converted into oil and a fatty crystalline matter, termed cholesterin, which appears in flat, rhomboidal, crystalline laminæ, with sharp outlines; the oil occurs in small globules of a highly refracting character, more or less aggregated in masses, and soluble in ether. In this state it presents a pulpy diffluent condition, and, owing to its yellow color, it may, as it occasionally has, be mistaken for pus. This conversion does not necessarily follow at stated periods, for it is probable that the fibrin may continue unchanged for a long time, until such a tendency prevails in the constitution of the individual of a cachectic or degenerative character, as to give rise to the secondary process. The lining membrane of the artery investing the atheroma, in the first instance, becomes thicker, and assumes a darker color, and is capable of considerable distension by the morbid product. This at first occurs

Atheroma is derived from 8pm, wheat-grits, a pap made of them, hence apa, an unclassical term, a pulpy substance.