=Syphilitic Tumors=, from the size of a pin’s head to that of the fist, may be found in the liver. They are of a gray, whitish or yellow color, made up of cells of an irregular form, which show a tendency to cheesy degeneration, or to such softening as to give the appearance of an abscess. Blood-vessels of the Liver. _The hepatic artery_ is sometimes found with aneurismal enlargements, and rarely contains an embolus. _The portal vein_ is frequently found containing a fibrinous clot, constituting thrombosis. Such clots may result from pressure on the vein from the presence of some morbid growth in the liver, or from a tumor in the mesentery or some other part, obstructing the portal vein below the liver; or from suppurative disease of ulceration of the several organs from which the portal vein arises. They may be a cause, or result, of phlebitis, and may give rise to jaundice, and sometimes to abscess of the liver. _Dilatation_ of the portal vein may result from obstruction of the capillaries of the liver in chronic atrophy or cirrhosis; or from the presence of thrombi, or pressure by various morbid growths. _Calcification_, not only of the portal vein within the liver, but of its various branches of origin within the mesentery, omentum, etc., may occasionally be met with.[26] _The hepatic veins_ may be found presenting the same abnormal conditions as the portal vessels. Animal Parasites. The liver has long been known as a favorite resort for different parasitical animals, the most common of which, is that of the larval form of one of the tapeworms—_the Tænia echinococus_—constituting when developed in the liver, what is known as an _acephalocyst_ or _hydatid_. =Hydatid Tumors= of the liver, arise in the following manner:—The several tapeworms pass through three stages of development, these never being completed however in the same animal. The Tænia echinococus, acquires its adult form, only in the intestines of the dog or wolf. The mature segments, each of which are filled with vast numbers of eggs, are voided with the fæces, into which the eggs are discharged. These soon develop into a minute embryo, with one extremity provided with numerous little hooks. If taken into the stomach of an herbivorous animal or man, this embryo pierces the walls of the intestines, enters a blood-vessel, and finally lodges in some of the tissues or organs, more frequently the liver, where it develops into a sac-like body, known as a _cysticercus_ or _hydatid_, the second larval form. When the embryo is taken into the stomach of other animals, no further development takes place. While in the hydatid, or second larval form, by a peculiar process known as alternate generation, there may be a reproduction of cysts to an almost endless extent within the parent cyst, or secondarily in other parts.