To all this M. Vacca replies, and we think very reasonably, that, however skilful in anatomy and dextrous in the use of his instruments a surgeon may be, that laying bare a large arterial trunk, tying it, and keeping a compress and ligature in a wound for some days, must necessarily occupy a certain degree of time, and produce some irritation;-that the placing the sides of the artery merely in contact does not, in fact, subtract one atom from the compression made upon it, nor does the interposition of the cylinder lessen that compression; the only difference being, that it is immediate on the posterior part of the vessel, and mediate on the anterior: " but still it is compression." It is not necessary entirely to interrupt the circulation of blood in a vessel, to produce inflammation and suppuration; an irritation kept up for a certain length of time is quite sufficient for this purpose: and it is not to be wondered at if, although adhesive inflammation should in the first instance be excited, that suppuration and ulceration should follow. "Do we not (says M. Vacca,) see the same thing occur in the simplest wounds, which have not been irritated by dissection, nor by the presence of foreign bodies, and which display some slight adhesions, and afterwards suppurate abundantly?" (p. 7.) To illustrate still further the necessity of the occurrence of suppuration in such wounds, he adduces the familiar instance of a thorn which has remained in the flesh for three or four days, and which, although then extracted, will not prevent the parts from inflaming and suppurating, in a great majority of cases.

To Scarpa's second objection, which is couched in terms expressive of his astonishment that any one should doubt the permanent obliteration of an artery at the point where it is tied, provided the ligature has remained in its situation for four days, our author replies:

"My doubts would appear reasonable, although unsupported by those observations and experiments which convert my doubt into mathematical certainty. If you will give yourself the trouble to put together all the existing observations, dispersed in various works and Journals, on this particular point, it is most certain that these would be more than sufficient to demonstrate that, at the epoch above mentioned, the coats of the artery are found to be sufficiently re-united to resist the rush of the blood; and this proposition has never been impugned by me. But, sir, a much greater number of observations than you could ever bring together would not be able to show the impossibility of union not taking place, if that be true, which I conceive to be proved beyond a doubt, namely, that inflammation in different individuals, though produced from the same cause, máy develop itself sometimes earlier and sometimes later.

"But I go farther. Facts are not wanting, that the arterial parietes in the human subject, not united after having been tied for four days.

from which it results although healthy, are M. Dupuytren, in the

dissection of a man, aged forty-two, who died after the operation of ligature on the carotid artery, the sixth day after the operation, found the following appearances:-All the parts comprised in the operation were in that state of inflammation which confounds all the tissues, augments their density, and diminishes, their power of resistance. The ligature comprised only the artery and a few fibres of the sterno. hyoideus; there was neither coagulum nor blood in the interior of the vessel; the point which was tied was puckered up, and had become so contracted that it was impossible to restore its natural calibre without tearing it. It is true (continues M. Vacca,) that this man had suffered from violent hemorrhages before the ligature of the carotid, but still the parts had been susceptible of inflammation; and, as it was the sixth day, that is, the period which, at the very latest, you admit of the action of the ligature,-it is clear that the blood would at that period have passed through the vessel, notwithstanding its presence.

Hodgson details another interesting case, which applies excellently to our purpose. In an elderly man, who had suffered a very great loss of blood, the external iliac artery was tied: at the termination of the fourth day, the man died. The dissection of the body showed the li gature in its situation, without inflammation externally, and without any union between the coats of the artery, although they had been completely divided by the ligature; a method which causes inflammation to develop itself rather more quickly. Are you of opinion that, in this case, in which, from the age of the patient and the hemorrhage he had suffered, the removal of the ligature ought, according to your opinion, to have been deferred for two days longer oaly; that those two days would have been sufficient to have lighted up the adhesive inflammation, and to render the adhesions sufficiently firm to resist the flow of the blood? And, if you admit that it is necessary to retard the removal of the ligature to the sixth day, because old age, weakness, and other causes unknown, may delay the formation of the adhesions and coagula, how can you establish, with mathematical precision, that this union may be delayed to the sixth day, and no longer?" (p. 10.)

Our author fairly admits that he cannot look for a favourable result, if any serious disease exists in the coats of the artery; but he does not fear the longer continuance of the liga ture, because it has already done all the mischief it is capable of doing in such cases; and as these cases cannot generally be distinguished a priori, leaving the ligature is of the greatest use in the one instance, and a matter of indifference in the other. In confirmation of this opinion, our author relates the following

case:

"A man, of the name of Caparrini, had his crural artery tied, in the hospital of Santa Maria Nuova, at Florence, for the cure of a popliteal aneurism. At the beginning of the fourth day, the ligature was removed. No symptoms, to give uneasiness as to the result, came on for several lays: the circulation by the collateral branches was established; there was no inflammation of the limb: but a fever came on, which was at NO. 291. 3 K

first considered as gastric, and afterwards as a low nervous fever, and the patient died on the twenty-fifth day after the operation. The examination of the body proved satisfactorily, to all present, the ulceration of the artery on the posterior and internal surfaces, and which had, at that point, consumed the entire coats of the vessel; the iliac arteries and the aorta not appearing to be thickened. But, even granting that in this case there was a diseased condition of the arterial system, this observation shows that you have been mistaken in reckoning upon the artery not being cut through when the ligature is removed, the vessel being in a diseased state."

The above case is the more valuable as it occurred in the practice of a firm partizan of Scarpa's opinions.

In allusion to a case recorded by Sir ASTLEY COOPER, Vacca observes as follows:

"We take very different views of this (Cooper's) observation: the blood which passed through the vessel thirty-two hours after it had been tied, proves that period not to have been sufficient to form adhe sions or coagula strong enough to arrest the current of blood. The blood which did not pass forty-eight hours after the application of the ligature, proves that the adhesions, &c. were then strong enough to put a stop to the circulation through the vessel. The hemorrhage which appeared on the twelfth day, proves that the coats, which were not ruptured on the fourth day, gave way after the ligature was removed; or that the adhesions and coagula, which governed the impetus of the blood in the first days, were at length overcome by the force of the circulation. Reflect, now, that if the artery had been in the diseased condition that you imagine, and had not felt the stimulus of the ligature, the blood would have continued to pass by the part tied after the forty-eight hours; and if the ligature produced the death of the vessel, as it was removed on the third day, it is clear that death may ensue even when the thread is removed so early; and which is precisely what I affirm, and what you deny." (p. 13.)

After obviating some objections that M. Scarpa had made to his reasoning, and which implied an apparent contradiction, our author continues:

"Permit me to examine what you have written relative to the band of lymph which surrounds the artery above and below the ligature, as well as at the point tied when the thread has fallen off. This band may certainly serve to bind and strengthen the artery both above and below the ligature, as well as at the point tied, when the cicatrix is formed; but it is not sufficient alone to oppose an hemorrhage, because, around the part which has been embraced by the ligature, the band (of lymph) is not formed until after the ulceration of the parieties of the artery, and at the period of the formation of the cicatrix. In different animals which I have made the subjects of experiments, I have not found the lymph, but suppuration, round the spot compressed by the ligature, if I examined them before the cicatrices had formed.”

We agree, also, with M. Vacca in considering this removal of the ligature as not so slight an affair as Scarpa would induce us to believe; and the publication of a memoir by MAZZONI on this subject confirms us in the belief; for from this it appears that, although originally a supporter of that opinion, he was induced to abandon it, from the pain and difficulty attendant upon the operation. With regard to the rapid recovery of those patients from whose arteries the ligature has been removed on the third or fourth day, our author denies the fact; and, from his experiments, he concludes that, when this is done, suppuration always follows. I do not deny (he says,) that excessive suppuration sometimes takes place round the ligature; that it becomes protracted, and insinuates itself into the cellular membrane of the artery, as well as that of the muscles; and that, in consequence, obstinatè secondary attacks take place upon the spot where the ligature had been placed. These unpleasant events are not, however, always the consequence of the ligature, and still less of its being left beyond the fourth day. Evils of this kind occur, as you well know, in wounds where no ligatures have been used, and in which there are no foreign bodies." (p. 18.) And here he quotes Scarpa's own opinion from his work on Aneurism, and which substantially admits this fact in its full extent. He acknowledges the inutility of the ligature in those cases in which the arteries themselves are diseased; but where there is only simple atony of the coats of the vessel, prolonging the sojourn of the ligature may be beneficial: such cases cannot be distinguished a priori, and that method, therefore, will not be hurtful in any instance, and may be of real use in other cases; and, whatever may be the fate of our theoretical views, it will always remain true, that if you meet with an individual in whom the adhesive process has been tedious, the blood will repass by the vessel; if you meet with a case in which, either from a total or partial want of sufficient vitality, inflammation, as soon as it appears, takes on the suppurative or ulcerative stages, (the causes which excited it remaining,) then suppuration or ulceration will not be avoidable; for the experiments made upon animals, and the observations on the human subject, incontestibly prove that the action of the ligature continued for four days upon an artery, produces a condition of its coats which generally conduces towards ulceration when they are in a sound state, and certainly much more so when they are diseased. If the state of the fluids can, as both parties agree, retard or accelerate the formation of coagula and adhesions, this forms an additional reason for suffering the ligature to remain. Finally, our author observes that he follows the opinion of many other surgeons, in believing that consecutive hemorrhage is more

frequent after aneurism than amputation, because the diseased condition of the vessel is more common in the first than in the second case.

We now come to the consideration of M. Vacca's second letter, and which contains the details of his experiments chiefly. He begins by lamenting that M. Scarpa did not repeat his (Vacca's) experiments, by which means any errors in their results might have been noticed, instead of forming conjectures as to the probable causes of the difference between their respective observations: in consequence of this, he is induced to give the following account of some fresh experiments which he performed.

"Although (he continues,) I had taken every precaution in my first experiment not to draw the ligature too tight, but, as I found that M. Panizza, in those which he performed, did not tighten the ligature so much as to put the parietes of the artery even into close contact, (as all surgeons have directed, and as you have taught, both in your work on Aneurisms, and in your memoir on Ligatures,) I was determined to follow the plan of the above-mentioned gentleman.

"My first experiment was performed on a large dog, about six years of age. I tied both the crural arteries. I drew the knot so lightly, that some of the assistants could not determine whether the circulation was entirely interrupted or not. On the fourth day, the wounds were suppurating from the left side the ligature was removed; it was suffered to remain on the right side. Not a drop of blood was lost from either side; but, twenty-nine hours after the excision of the ligature, a hemorrhage of arterial blood appeared from the part from whence the ligature had been removed, which lasted about an hour, moderate in the beginning, and at length becoming trifling, and which ceased without any assistance. The day after, a fresh hemorrhage made its appearance from the same part, much less in degree than the former, and which spontaneously and quickly ceased. The first loss of blood was calculated at six ounces, and the second at two. Five days after the removal of the ligature, the dog was killed. In the dissection, I found that the wound was in a state of suppuration, from the part whence the ligature had been removed, though not extensively; its edges were not swollen; the inguinal glands were somewhat enlarged. On laying bare the artery, I found it surrounded by suppuration, both above and below the point where the ligature had been; and I found the lymph, as usual, surrounding the vessel. On the spot where the cylinder, or compress, had rested, the artery was of a black colour. On tearing it open longitudinally, I found that the black point was a coagulum of blood, which lay over the erosion of the anterior part of the vessel, which was entire in all its other parts upon which the ligature had acted. On the right side, where the ligature remained, I found the same appearances, including the erosion of the anterior parietes, and the clot of blood that covered it; which in this case was not moved, (mark well,) the compress which corresponded with it not having been taken away.” (p. 23.)