The _Spindle-celled Sarcoma_, called also the fibro-plastic and recurring fibroid, is most closely allied to the fibroma. It consists essentially of fusiform cells, with well-marked nuclei and thin processes, sometimes split at the end. They are nearly in close contact, there being but little intercellular substance. The cells are parallel and arranged in bundles, which pass in all directions through the growth. “When cut, this sarcoma grates under the knife, and the surface exhibits a firm, tough, greyish or pale-yellowish appearance, similar to that of ordinary fibrous growth. After removal, they are softer and more succulent when they recur.” They grow from the periosteum, the fasciæ, and from the connective tissue in other parts. They are more frequently enclosed in a capsule than the other varieties. The _Giant-celled Sarcoma_, called also the _myeloid_ sarcoma, most frequently occurs in connection with bone. They consist of large, many nucleated cells, mingled with round or spindle forms, nearly in contact, there being but a sparse intercellular substance. On section, the surface appears smooth, compact, shining, greyish-white or greenish, with blotches of a dark crimson, brownish or pink hue. The giant-celled sarcoma is not a benign affection, but is the least malignant of the sarcomas. 2. =Carcinomatous Tumors.= “The _Carcinomata_ are new formations, consisting of cells of an epithelial type, without any intercellular substance, grouped together irregularly within the alveoli of a fibrous stroma. The cells are characterized by their large size, by the diversity of their forms, and by the magnitude and prominence of their nuclei and nucleoli. In size they vary from ¹⁄₆₀₀ to ¹⁄₁₅₀₀ of an inch in diameter, the majority being about five times as large as a red blood-corpuscle. They are round, oval, fusiform, caudate, polygonal—exhibiting, in short, every diversity of outline. The nuclei, which are large and prominent, are round or oval in shape, and contain one or more bright nucleoli.” There is generally but a single nucleus, two, however, are often met with, and they are even still more numerous in the soft varieties of cancer. The stroma varies in amount. It consists of a fibrillated tissue, forming by their peculiar arrangement, alveoli of various sizes and shapes, in which the cells are grouped. The stroma varies in character according to the rapidity of its growth. Where its growth is rapid, it will contain numerous round and spindle-shaped cells; where it is slow, or has ceased altogether, the tissue will contain but few cells, and will be dense and fibrous in character. The latter condition is most frequently met with. The blood-vessels are sometimes very numerous, and are always limited to the stroma, and never encroach upon the alveoli. This serves to distinguish the carcinomata from the sarcomata, since in the latter the blood-vessels ramify amongst the cells of the growth.