Acute suppurative inflammation occurs in connection with septic processes, which have been propagated to the liver.

(a) The Tropical abscess is scarcely ever met with in this country, except in persons who have been in hot climates, especially in India. Much doubt exists as to the cause of the inflammation which gives rise to the abscess. In a large proportion of cases it is associated with dysentery, and it is believed by many that the abscess in the liver arises by the amoeba coli or by septic microbes being carried from the ulcerated intestine to the liver. This view, however, is not beyond question, and post-mortem examination shows that the tropical abscess is by no means uniformly associated with dysentery. It is possible, indeed, that an existing abscess by causing congestion of the portal circulation may predispose to inflammation of the intestine (Finlayson). It is not unlikely that certain states of the liver predispose to the development of the agents in question, and that they may find entrance to the body without any lesion of the intestine.

A confirmation of this view is furnished by the fact, testified by Dr. David Wilkie of Simla, that in India, while the death rate from dysentery among natives is not far from that among Europeans, that from hepatitis is proportionally greater amongst Europeans, probably from predisposition, brought about by their mode of living and racial characteristics. Thus in the European and native armies from 1877 to 1886 the death-rate from dysentery per 1000 men was 1.33 and 1.25 respectively (or, including diarrhoea, 1.57 and 2.27), whereas the death-rate from hepatitis was 1 .45 in the European and 0.17 in the native army. This is more strikingly apparent in the deaths in the jails of India (natives), the death-rate being, dysentery and diarrhoea, 1877-1886, 19.13; hepatitis, 0.22.

The abscess is mostly, but not always, solitary, and before death it generally grows to large dimensions, causing great enlargement of the liver. Having approached the surface, it sometimes causes a marked projection from the liver. The abscess may rupture into the peritoneum and cause fatal peritonitis, or its capsule having become adherent to the abdominal wall the abscess may by and by find its way to the surface of the body, there to discharge. It also occasionally bursts in other directions, as through the diaphragm into the pleural cavity, or lung; into the colon or other part of the intestine; or into the gall bladder, from which the pus is carried to the duodenum. In these various ways the pus may be disposed of and perhaps recovery occur, but more frequently a wasting discharge from- the cavity of the abscess remains.

In other cases the abscess does not enlarge, but rather dries-in. A thick connective tissue capsule forms around it like the wall of a cyst, and the pus thickens to a cheesy consistence. Afterwards the contents may become calcareous and the disease become virtually obsolete.

(b) Pyaemic abscesses are produced by pyogenic micrococci conveyed to the liver by the blood. They may be carried by the hepatic artery, in which case they have generally been absorbed from a septic wound and have traversed the lungs. Such abscesses will usually be associated with similar metastatic abscesses in the lungs. On the other hand, the microbes may be conveyed by the portal vein, being associated with a septic thrombo-phlebitis in its radicles, or in the vein itself. The author has twice seen abscesses in the liver from the ulceration of gall-stones into the portal vein and consequent thrombo-phlebitis.

Where the source of infection is in the systemic venous system the abscesses may form without any visible thrombosis or embolism of the portal or hepatic vessels. It appears that, if the microbes are in the blood miching the liver, they may settle there just as other granular matter may do.

The microbes multiply and form zooglcea in the capillaries and interlobular veins, passing into the central veins. Wherever the colonies extend the liver tissue undergoes necrosis, the cells lose their nuclei and become individually indistinguishable. Inflammation is produced around, and there is here, as elsewhere under similar circumstances, an acute suppurative inflammation. The round cells accumulate around the necrosed portion, and gradually infiltrate it and break it down, so that an abscess forms.

The abscesses in this form are always multiple, and some of them may attain to large dimensions. In accordance with what has been stated the actual abscess is preceded by a grey or yellowish discoloration indicating the existence of necrosis of the tissue. There will be probably a group of such areas corresponding to necrosed hepatic lobules. Ultimately these break down and form a common abscess.

(c) Biliary abscesses occasionally form in connection with obstruction of the ductus choledochus. This will result when decomposition occurs in the stagnant bile and extends into the ducts in the substance of the liver. (See further on under Obstruction of Bile Ducts).