The tumor varies in size from a pea to that of an adult’s head, its shape being generally ovoidal, and its surface more or less lobulated. “It is of a soft, brain-like consistence, the central portions; where fatty degeneration is most advanced, often being completely diffluent. On section, it presents a white, pulpy mass, much resembling brain substance, which is often irregularly stained with extravasated blood.” Occasionally these tumors contain serous cysts of small size, as well as other adventitious products. When ulceration takes place; the sore is characteristic. “Its edges are thin, undermined, jagged, or irregular, while its bottom has a foul, bloody, fungous appearance. The parts around are of a deep red, livid, or purple color.” (_c._) _Melanosis._ Melanotic, or black cancer, is probably merely the result of a pigmentation of the encephaloid. It occurs most frequently in the eye and skin, and is occasionally met with in the viscera. The melanotic matter occurs in small masses, of a rounded, ovoidal, or irregular shape, with or without a cyst, from the size of a pin’s head to that of a walnut; of a dull, sooty, brownish, or black color. They are generally invested by a distinct capsule, formed out of the cellular tissue in their immediate vicinity. “Under the microscope, it is seen to consist of a fibrous net-work, including numerous alveoli, filled with free, unadherent pigment cells, occupied by colored granules, a few of the larger or older ones containing sometimes a nucleus with its nucleolus. Free pigment granules are also found in great abundance.” (_d._) _Colloid._ The colloid, alveolar, gelatiniform cancer, is the most uncommon form of heterologous formations. It is regarded by some, as simply one of the preceding forms which has undergone mucoid or colloid change. It is most frequently met with in the stomach, the intestines, and the periosteum; and can appear at any age, but is most common between the thirty-fifth and fiftieth year. The tumor varies in size, from the size of a marble to an adult head, is globular or irregular in shape, of a firm, dense consistence, with a rough, knobby, or distinctly lobulated surface.