The Melanoid tumour is rather of rare occurrence in the human subject; it originates in the cellular tissue, and most frequently attacks the internal viscera; sometimes it occurs in the eyeball, where it has been seen with the encephaloid disease, and occasionally melanotic matter is diffused amongst the cellular tissue throughout the whole body, even in that of the bones. The external surface of the tumour is generally of a shining and mottled appearance; internally it consists of a homogeneous black matter infiltrated into the cellular tissue, which is condensed, and in some cases distinctly increased in vascularity. The tumour, seldom of a large size, extends chiefly in a lateral direction. Occasionally it is pretty firm; in other instances it is soft, broken down, and semifluid. The melanotic matter is not always so deposited as to form a distinct tumour, but frequently seems to be sparsely infiltrated into the cellular tissue; and occasionally it is diffused in so minute a quantity as merely to tinge the part, or form dark streaks. Sometimes it is infiltrated in the substance of an organ, and sometimes it is effused on its surface; occasionally it is surrounded by a distinct delicate sheath; usually it is confined by no envelope, excepting the partial condensation of surrounding parts. In the skin it sometimes presents in a tubercular form. The tumour is said to be chiefly composed of albumen, mixed with a peculiar colouring matter. The disease mostly occurs in the trunk, seldom in the extremities; it is not uncommon in the orbit, and in the internal organs the melanotic deposits are generally both numerous and extensive. There is seldom pain, and the patient seems to suffer chiefly from lassitude and extreme debility, which gradually increase; anasarca frequently supervenes; the functions of the organs affected are much impeded, or even altogether destroyed, and thereby the sinking of the powers of life is accelerated according to the viscera affected and the extent of the disease. Melanosis occurs most frequently in advanced life, though it is not confined to it; whereas encephaloid attacks indiscriminately all ages. OF CARCINOMATOUS TUMOURS.