Dr. Porta has also performed seventy experiments to determine the value of a loose or slack ligature. The kind of animal, the material of the ligature, and, above all, the degree of tightness of the ligature, have greatly influenced the results; but the sum of the whole may be said to be that either by clot, exudation of lymph, or slow contraction from thickening of the cellular coat, the artery was closed in half the cases; in the other half it remained pervious, without any, or with only very slight, alteration in its texture; while, in a few cases, a part of the walls became ulcerated or eroded, and gave rise to fatal hemorrhage. These experiments upon the loose ligature illustrate the effects of the ligature of reserve, which was at one time the fashion, as a supposed safeguard. 2. The mediate ligature has for its object the closure of the artery without injury to its coats. It is termed also flat ligature, ligature with a small cylinder, Scarpa's ligature. For the ligature a small riband is generally used, formed of several simple waxed threads, and as the intermediate body a small cylinder, or small roll of adhesive plaster. To determine the value of this method the author made one hundred and twenty experiments-thirty-five with the permanent, and eighty-five with the temporary ligature. He has also collected ninety-six cases of mediate ligature performed upon the human subject, that both in its permanent and temporary application the results in man and the lower animals are similar. The following table will show these results in the eighty-five experiments upon the temporary mediate ligature: The exact result of the mediate permanent ligature is not given; but the author states that, instead of being more secure than the common circular thread, suppuration is much more common, the artery is deprived of its cellular coat, and the internal clot is the only safeguard against hemorrhage. 3. The method of double ligature, with division of the artery between, was produced in forty-five cases-thirty-five with simple incision, and ten with removal of a portion of the artery of various lengths. The mechanical results are the same as in the common method, with the addition of ecchymosis, retraction of the divided extremities, and impulsory movement of the cardiac extremity. The first vital phenomenon after the operation is inflammation of the cellular coats, with copious exudation of lymph, XLIII.-XXII. 7 which afterwards becomes modelled into a cellular cylinder, and restores the continuity of the vessel. This cylinder varies from a few lines to two inches in length, according to the degree of retraction after division of the artery. At first it is much more voluminous than the vessel, but afterwards it becomes smaller, firmer, and fibrous, and is reduced to the state of a thin ligamentous coat; or it is completely absorbed, leaving the ends of the artery permanently separated; or very rarely (it only occurred in two experiments) the closed extremities of the artery are united by a new cellular tube, in the midst of which the two ligatures are found. In ten experiments made upon the carotids of dogs, with removal of a portion of artery between the two ligatures, the cylinder formed, as in simple division when the portion removed was very small, but when it exceeded two centimeters the cylinder was not found, and the extremities cicatrized separately without union between them. In the forty-five experiments with the double ligature, hemorrhage and corrosion of the cardiac extremity occurred in three cases, which was never observed after the common ligature. A table of the results of six hundred ligatures in the human subject, which we shall presently relate, will be the best test of the practical value of the method. The conclusions of the author are as follows: "The temporary and loose ligatures are simple methods, destined, from their inefficiency, to remain neglected. The permanent mediate ligature, formerly recommended from prejudice, should meet the lot which the same method in wounded arteries for a century has suffered. The temporary ligature, although at first sight tempting, after the above demonstrations, and the facts drawn from other authors, may be declared to be a difficult, complicated, and uncertain method. To this the double ligature adds violence, and a multiplicity of proceedings, frequent impossibility of execution, copious suppuration, and greater tendency to hemorrhage. Thus the circular ligature alone remains, to which good sense and practice have already accorded the preference, now approved and justified by science." (pp. 108-9.) The tabular view of six hundred ligatures of the large arteries in man has been prepared with so much care, and affords so much information, that we give it entire : |