larly contracted and lobulated (Fig. 255). Gummata may occur in any part of the organ, and may be single or multiple, presenting themselves as rounded, yellowish, or grayish masses, ofttimes showing central necrosis and surrounded by connectivetissue hyperplasia (Fig. 104). Complete cicatrization may lead to decided scar-formation. In addition to these forms, congenital syphilis may manifest itself in the form of a uniform, diffuse connective-tissue hyperplasia and round-cell infiltration. The livercells are pushed apart and are ill-developed or atrophic (Fig. 256).

Leprosy occasionally affects the liver, causing the formation of nodular masses.

TUMORS.

Fibromata, lipomata, and myomata are occasionally observed as nodular masses, but have little significance.

Angioma is a more important form. This tumor occurs upon the surface of the organ, and is usually of small size, rarely exceeding that of a walnut. It is more commonly found in persons who have died at advanced years than in young persons. Angiomata appear as dark-red or bluish, slightly elevated areas, either sharply outlined and encápsulated, or merging gradually into the surrounding tissue. Microscopically they are found to be cavernous angiomata, and doubtless owe their origin to dilatation of the capillaries, with coincident atrophy of the liver-cells.

Sarcoma of the liver may occasionally be primary, but is exceedingly rare. Secondary sarcoma, on the other hand, is very common, especially the melanotic form following primary sarcoma of the eye.

Lymphadenomata are frequent in the liver in the course of the generalization of leukemic lymphadenoma; but it has not as yet

been fully determined to what extent these are to be considered as true tumors, and to what extent as mere infiltrations of leukocytes consequent upon the enormous leukocytosis of this disease. Similar lymphomatous nodules, though much less marked and numerous, occur in typhoid fever and other infectious diseases.

Adenoma of the liver is met with in several forms. There may be either nodular masses, more or less encapsulated and of grayish-white or pinkish color, or a form of diffuse infiltration of the liver-substance by encapsulated nodules of similar character. Considerable cirrhosis of the liver may be associated with the latter cases, and they cannot be clearly distinguished from cirrhotic cancer (see below).

Carcinoma of the liver is rather rare as a primary tumor, but, like adenoma, may be nodular or diffuse. The nodular or massive cancer appears as a single mass of varying size, ofttimes surrounded by local metastatic nodules. On section the color is grayish or pinkish, and there may be central necrosis and soften

ing. Diffuse hepatic cancer occurs as a widespread and more or less uniformly distributed infiltrating growth. Not rarely in such cases there is associated cirrhosis, and the macroscopic appearance of the liver may be strikingly like that of an ordinary cirrhosis, though the liver is sometimes much enlarged (Fig. 257). The terms cirrhotic cancer and cancer with cirrhosis have been applied to this form. Finally, the diffuse form may surround and spring

from the periportal structures, and may ramify in the form of an interlobular infiltration.

Formation and Structure of Adenomata and Carcinomata.

Microscopically there is no sharp dividing-line between these growths. The adenomata present tubular formations of a more or less elongated and tortuous character, composed of cylindrical or of more irregular-shaped epithelial cells. In some instances these are strikingly like new-formed biliary capillaries, and perhaps they occasionally originate from these structures. More commonly, however, the origin would seem to be from the hepatic cells themselves. The columns of hepatic cells undergo proliferative change, and at the same time become somewhat transformed, assuming the tubular arrangement of adenoma. Occasionally adenoma and cystic adenoma originate from the mucous glands of the larger biliary ducts. When cirrhosis is associated with adenomatous infiltration it is probable that the primary change is a cirrhotic overgrowth which induces secondary hyperplasia of the epithelial cells, instead of degenerative changes, such as usually result from the pressure of new-formed fibrous tissue.

Carcinoma of the liver is similar in origin and structure to adenoma. The cellular acini and tubules are more irregular, and there is an evident tendency to diffuse infiltration and atypical formation of acini.

Secondary carcinoma of the liver is very common as a result of carcinoma of the stomach or of other parts of the portal

FIG. 258.--Metastatic nodules of carcinoma on the surface of the liver (Hanot and Gilbert).

distribution. It is usually due to cancerous embolism in the portal capillaries, with subsequent development of the emboli (Fig. 259). The liver becomes enlarged, and presents nodular masses upon its surface or within its substance. These nodules vary from the size of a pea to that of an apple, and are frequently

sharply delimited by capsule-formation, especially those which have reached considerable size. Not rarely the nodules are indented upon the surface (umbilicated) from central softening or from contraction of fibrous tissue within (Fig. 258). Secondary cancer of the liver may also result from direct extension of cancer of the stomach or of the gall-bladder and biliary ducts. In all cases the new growths tend to compress the bile-ducts and lead to biliary pigmentation of the liver-substance, as well as to general icterus.

FIG. 259. Secondary cancer of the liver: a, columns of liver-cells filled with bile-pigment; b, endothelial walls of capillaries; c, carcinomatous emboli in the capillaries (Hanot and Gilbert).

Cysts of the liver are rare. They may spring from the biliary ducts which have suffered simple dilatation, or from the mucous glands of the larger bile-ducts (cystic adenoma). Occasionally small cysts are seen which suggest origin from dilatation of the lymphatic channels.

PARASITES.

Of the protozoa, coccidial Psorospermia (Fig. 260) have been occasionally demonstrated in the human liver in small nodular tumors; but a more important parasite is the Amoeba coli, occurring in abscess of the liver secondary to amebic dysentery. The pus of the abscess may contain immense numbers of the amebæ, and doubtless these organisms bear an important relation to the lesion, perhaps causing necrosis by their own activity and then

liberating pyogenic organisms which they have carried from the intestines, and which complete the pathologic process. The larval Pentastoma denticulatum is occasionally met with.

The Distoma hepaticum and the Distoma lanceolatum occasionally infest the biliary ducts, and the Distoma hematobium the portal vein. Ascarides sometimes creep upward in the biliary ducts as far as the branches within the liver. The Cysticercus cellulose is a rare parasitic formation.

Echinococcus cyst.-The most important parasitic disease of

rabbit.

the liver is the echinococcus-cyst, caused by the presence of the larvæ of the Tania echinococcus (see Part I.). This parasite occasions cystic formations of various kinds within the liver. The cyst has a double wall: the outer, of connective tissue; the inner,

FIG. 261.-Echinococcus multilocularis (Luschka).

a parenchymatous membrane, from which buds (brood-capsules) and secondary cysts are prone to originate. There may be a single cyst containing clear liquid of low specific gravity, or a mother-cyst containing daughter-cysts, either upon the inner wall