g. Pus. Abscess in the liver occurs in two principal forms, either as a single abscess of large size inclosed in a cyst, or as numerous small collections of matter, bounded by the substance of the liver or diffused amongst its lobules. In the first form it constitutes idio pathic abscess of the liver, a disease of tropical countries, and rare in our temperate climates. Abscess is generally preceded by acute inflam mation and more rarely by chronic inflamma tion, and attains an enormous size, engrossing the whole of the right lobe and sometimes con verting the entire organ into one huge cyst. The cyst may be thin or thick, and more or less organised. Andral and Louis conceive that its internal surface is analogous to a mucous membrane. The quantity of pus contained in one of these abscesses varies from a few ounces to several pints. My friend Dr. Macnaught, who has seen much practice in the West Indies during a residence of twenty-two years in Jamaica, has observed that abscess in the liver occurs more rarely in the West than in the East, and, moreover, that this disease affects the Euro peans and not the Negroes. During the whole of his experience he never saw a single case of abscess in the liver in the Negro, and among the white population of his district only four well marked instances.
The irritation of abscess causes the effusion of lymph and adhesion to the abdominal pa rietes or to the adjoining viscera; ulceration fol lows, and the contents of the cyst are discharged through the artificial opening. The situations in which the matter escapes from the cavity of the abscess are various. 1. It may burst externally, making its way either between the ribs or up wards towards the walla. In a case observed by Dr. Macnaught the abscess pointed at the epigastrium and was opened by the surgeon in attendance. 2. It may become adherent to the diaphragm and burst into the pleura. 3. It may cause adhesion between the serous membrane of the liver and of the diaphragm, and between the latter and the pleura pulmonalis, and the matter may escape into the lung and be coughed up, as in the case already detailed, which occurred to Dr. Munro. 4. In rare cases the pus has been effused into the cavity of the peritoneum. 5. The abscess may become adhe rent to the stomach, duodenum, or colon, and the matter be discharged into the alimentary canal. A well-marked case of abscess dis charging its contents into the stomach occurred to myself in the case of a woman who has since perfectly recovered. About two pints of matter were vomited by the patient. In a simi lar case observed by Dr. Macnaught the patient recovered. In two other cases, where the matter was poured into the intestines, the patients died. 6. Abscess has been seen to open into the gall-bladder, and the pus to be conveyed thence through the ductus communis choledochus into the duodenum. 7. In one case the matter was discharged into the vena cava; and in another, 8, described by Dr. Smith, into the pericardium ; and in a case detailed by Dr. Graves," the abscess opened both into the stomach and pericardium.
Besides the preceding form of abscess, which is idiopathic in its origin, abscess may occur in the liver from external injury, as from a blow. The inflammation attending upon this injury is much slighter than that which gives rise to idiopathic abscess; the collection of matter is generally smaller, and terminates either by dis ng its contents or by absorption.
The second variety of abscess in the liver, that in which numerous purulent collections exist, depends for its cause upon the occurrence of wounds or. of surgical operations. The suc cession of abscesses in the liver from wounds, particularly of the head, has long since been admitted as a well-established fact, for the explanation of which numerous theories have been invented. Theory, however, has now yielded before facts,—facts, too, of the most interesting and satisfactory kind, for which pathology is indebted to the genius and indus try of Cruveilhier. The experimental re searchesf of this excellent author, published in 1826, enabled him to establish a law of the utmost importance in the consideration of the phenomena of disease, viz. that " tout corps etranger introduit en nature dans le systeine veineux determine lorsque son elimination par les emonctoires est impossible des absces visce raux entierement semblables a ceux qui suc cedent aux plaies et aux operations chirurgicales, et ces absces sont le resultat crime phlebite capillaire de ces memes visceres." These experiments consisted in the introduction of metallic mercury into the veins of an animal, say of the lower extremity. In the course of twelve, eighteen, or twenty-four hours the animal experienced much difficulty of breathitag, and soon expired. Upon inspection globules of the mercury were found in the lungs. If a smaller quantity of mercury were introduced the animal would live for several days or weeks, and upon examining the lungs at different periods the globules were at first seen to be surrounded by a red induration and afterwards by pus. This experiment was varied by pouring the mercury into the medullary cavity of a bone with pre cisely the same results ; in one instance he placed a single globule in the medullary cavity and found it again at the end of a month in the lungs, divided into several minute globules, each of which formed the centre of a small tuberculous abscess. Cruveilhier then injected a small quantity of mercury into one of the omental veins of a dog—the subject of umbili cal hernia; the dog was killed in the third month after the operation, being reduced to a state of marasmus. Upon inspection the liver was found filled with small abscesses, each surrounding a small globule of mercury. Having by means of these experiments satisfied himself that the lungs were the barrier to all foreign matters introduced into the general circulation, as was the liver of those admitted into the abdominal circulation, he proceeded to another series of experiments. Opening a vein in the hinder extremity of a dog he introduced into it a long piece of stick, which gave rise to phlebitis and the secretion of pus. The pus thus produced being carried into the circulation excited, in the first instance, abscesses in the lungs, and, secondly, in the liver. Upon these facts and upon a multitude of excellent observations Cruveilhier founds his opinion that abscess in the liver from wounds and surgical operations is always preceded or accompanied by purulent collections in the lungs, and always results from the same cause, viz. from capillary phlebitis, consecutive upon phlebitis in the neighbourhood of the wound, and im mediately produced by the irritative action of globules of pus brought from the diseased veins to the capillaries of the structures in which the secondary suppuration is developed.