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hence it appears most prudent, that so long as our attempts to draw away the ligature meet with much resistance, they should only be exerted in such a gentle and gradual manner, as may promote ulceration of the part by which the ligature is confined, without endangering laceration of the recently united parts.

"The permanent changes which take place in an artery, and in the circulation through a limb, in consequence of the application of the ligature, are precisely the same as those which happen from the division of an artery, and which I have described in Chapter I. Section III. The portion of the arterial trunk which has been tied, undergoes a gradual contraction and obliteration to the first collateral branches, and finally dwindles to a mere fibre.

"The collateral branches are unusually distended and excited to stronger action from the moment that a complete obstruction is formed in the trunk, and, consequently, the commencement of their enlargement may be referred to that period. Their increase of size seems to be proportioned to the exigencies of the particular case; thus, if the limb has been amputated, it does not appear to be finally very considerable; but if the limb remain entire, and only the natural course of the circulation be obstructed through the main arterial trunk, their enlargement is much more conspicuous, and is particularly observable in the small inosculating ramifications of the collateral branches, by which the circulation appears to be carried on, after a certain time, as vigorously in the limb, the principal artery of which has been obstructed, as in that which has preserved its natural circulation.

“The effects of tying an artery properly appear then to be the following:

“1°. To cut through the internal and middle coats of the artery; and to bring the wounded surfaces into perfect apposi

tion.

66 “2o. To occasion a determination of blood on the collateral branches.

"3°. To allow of the formation of a coagulum of blood just within the artery, provided a collateral branch is not very near the,ligature.

"4°. To excite inflammation on the internal and middle coats of the artery, by having cut them through, and, consequently, to give rise to an effusion of lymph, by which the wounded surfaces are united, and the canal is rendered impervious: to produce a simultaneous inflammation on the corresponding external surface of the artery, by which it becomes

very much thickened with effused lymph; and, at the same time, from the exposure and inevitable wounding of the surrounding parts, to occasion inflammation in them, and an effusion of lymph, which covers the artery, and forms the surface of the wound.

"5°. To produce ulceration in the part of the artery around which the ligature is immediately applied, viz. its external coat. แ "6°. To produce indirectly a complete obliteration, not only of the canal of the artery, but even of the artery itself to the collateral branches on both sides of the part which has been tied.

"7°. To give rise to an enlargement of the collateral branches.

"In the account which I have now given of the effects of the ligature on an artery, I have had in view only those instances, in which the ligature has been applied on the extremity of a divided artery, or those in which two ligatures have been applied on an artery, at a small distance from each other, and the intermediate portion divided. But, from observation on the human subject, it appears, that the effects are different, or at least their accomplishment is much more likely to be interrupted, when one or two ligatures are applied on an artery without any subsequent division of it."

The author concludes the work with some remarks on the form of the ligature, which he recommends should be of moderate size, round, and uniform, and applied with considerable firmness, so as to ensure the division of the two more internal coats of the vessel, and to prevent the ligature from being thrown off by the force of the circulation. From the toughness of the external coat, it cannot be cut through without considerable difficulty, an accident which the older surgeons very much dreaded. It is hardly necessary now to state, that the artery should be tied as clear as possible from contiguous substances, particularly large nerves. For some time after securing a large vessel, the limb ought to be kept as quiet as possible, hemorrhage having been caused as late as the twenty-first day, by sudden and violent exertion.

In analyzing European publications it is not our intention so much to pass judgment on their merits or defects, as to lay

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before our readers what appears to us new or important in them, but we cannot take our leave of the work before us without again expressing our high opinion of its value. It is, in our estimation, a perfect model of the manner in which physiological inquiries ought to be conducted; and had truth been thus always sought, how different would have been the state of medical science. Had physiologists, instead of indulging their fancies in idle dreams about the functions of parts which are perhaps inscrutable, certainly unimportant,—had they, like Dr. Jones, coolly inquired, patiently observed, and candidly related, we should not now have occasion so often to exclaim against the uncertainty or inefficacy of the healing art. Happily for mankind, this rage for explaining every thing seems to be passing away; physicians at last are not ashamed of being ignorant of what perhaps is inexplicable; and medical authors are now content with pointing out the method of curing diseases, instead of bewildering their readers and themselves in the mazes of hypothetical nonsense.

A Treatise on the Anatomy, Pathology, and Surgical Treatment of Aneurism, with Engravings. By ANTONIO SCARPA, Professor of Anatomy and Practical Surgery in the University of Pavia, &c. Translated from the Italian, with Notes. By JOHN HENRY WISHART, Fellow of the Royal College of Surgeons, &c. 8vo. pp. 504. Edinburgh. 1808.

THIS work appears to have effected an almost entire revolution in the opinions of physiologists and surgeons, as to the proximate cause of aneurism; and even the most sceptical must allow that what has been denominated true aneurism, that is, an aneurism from a distention of the coats of an artery, is a very rare disease if indeed such cases ever occur. For our author has incontestably proved, that in a great majority of instances VOL. 1.

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at least, whether the disease be in the aorta or its contiguous branches, or in the limbs, whether the cause be internal, or whether the vessel has been injured by accident, that a solution of continuity in the coats of the vessel uniformly takes place, and that the sac is formed by the cellular sheath and membrane surrounding the artery.

The following is the account which our author gives of the formation of thoracic aneurisms from internal causes.

"13. The phenomena which are observable in the artificial distentions of the thoracic or abdominal aorta, present themselves likewise, in my opinion, in the case of a morbid degeneration of the internal coat of the artery, during which, that coat becomes in some places weak, or very rigid and friable, and is thinned, separated, or ruptured, by the repeated jets of blood thrown from the heart. The internal coat of an artery being ulcerated or lacerated from a slow internal cause in some point of its circumference, the blood impelled by the heart begins immediately to ooze through the connections of the fibres of the muscular coat, and gradually to be effused into the interstices of the cellular covering, which supplies the place of a sheath to the injured artery, and forms, for a certain space, a kind of ecchymosis, or extravasation of blood, slightly elevated upon the artery. Afterwards, the points of contact between the edges of the fibres of the muscular coat being insensibly separated, the arterial blood penetrating between them, fills and elevates, in a remarkable manner, the cellular covering of the artery, and raises it after the manner of an incipient tumour. Thus, the fibres and layers of the muscular coat being wasted or lacerated, or simply separated from each other, the arterial blood is carried with greater force, and in greater quantity than before, into the cellular sheath of the artery, which it forces more outwards; and, finally, the divisions between the interstices of the cellular coat being ruptured, converts it into a sac, which is filled with polypous concretions, and with fluid blood, and at last forms, properly speaking, the aneurismal sac; the internal texture of which, although apparently composed of membranes placed one over the other, is, in fact, very different from that of the proper coats of the artery, notwithstanding the injured artery, both in the thorax and in the abdomen, as well as the aneurismal sac, is covered externally, and enclosed within a common smooth membrane.

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§14. In the very considerable number of aneurisms of the arch, and of the thoracic and ventral trunk of the aorta, commonly regarded by medical men as true or incysted, or as formed by a dilatation of the proper coats of the great artery, which I have had an opportunity of examining, I have not found a single one, in which the rupture of the proper coats of the artery was not evident, and in which, consequently, the aneurismal sac was produced by a substance completely different from the internal or muscular coat of the injured artery. To ascertain the truth, and confirm the constancy of this fact, it is not necessary that one should be possessed of uncommon knowledge in the art of dissection, but only that he be disposed to see things as they really exist, and that he undertake to examine the aneurism in the situation in which it is found, and without removing the parts which surround it, or at least that he do this with due circumspection. For, as I have asserted above, very often the examination which is made by medical men, of internal aneurisms in the dead subject, consists of little more than a simple division of the fundus of the tumour, without paying attention to the cellular sheath which surrounds the artery, above and below the place of the aneurism, and without examining the disposition and particular characters of the proper coats of the aneurismatic artery, and comparing it with the substance which forms the parietes of the aneurismal sac; and what is still worse, the aneurism is examined by some, after being removed from the body, and filled with some substance, or dried; in which preparations, there is nothing to be seen but confusion and obscurity, in every thing which relates to the true nature and structure of the parts by which the tumour is formed.

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§ 15. A circumstance very important to be known relative to this subject, has been hinted at above; viz. that the aneurismal sac never comprehends the whole circumference of the injured artery, but only a portion of the arterial tube, to which the tumour is united on the one or the other side. At this place, the aneurismal sac presents, as it were, a species of constriction, or neck, beyond which the sac of the aneurism is more or less enlarged, or expanded, and sometimes to an enormous degree. This circumstance would never accompany aneurism, or rather, quite the contrary would be found, if the aneurismal sac were produced by an equable distension of the tube and of the proper membranes of the aneurismatic artery. For, in incipient aneurisms, at least, the greatest effect of the distention acting upon the tube of the artery, the greatest size of the tumour ought to be in the artery itself, or in the beginning

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