. The principles and practice of veterinary surgery . TUMOURS. CELLULAR TUMOUES. Sarcomata and Caecinomata.—A sarcoma is a cellulartumour in which the elements are of the mesoblastic are extremely malignant, infiltrating locally, and givingrise to secondary tumours in distant organs by metastasis,which usually takes place by the blood-vessels, thus contrasting with the carcinomata, in which the infecting cellsare carried by the lymphatics. The supporting tissue in sarcomata is very scanty, and indeedmay appear to be entirely wanting, the tumour being made upof a mass of cells. The bl
. The principles and practice of veterinary surgery . TUMOURS. CELLULAR TUMOUES. Sarcomata and Caecinomata.—A sarcoma is a cellulartumour in which the elements are of the mesoblastic are extremely malignant, infiltrating locally, and givingrise to secondary tumours in distant organs by metastasis,which usually takes place by the blood-vessels, thus contrasting with the carcinomata, in which the infecting cellsare carried by the lymphatics. The supporting tissue in sarcomata is very scanty, and indeedmay appear to be entirely wanting, the tumour being made upof a mass of cells. The blood-vessels are remarkable for thetenuity of their walls, some of them appearing to be merechannels among the cells. This explains the readiness withwhich metastasis by the blood takes place in sarcomata. Thecells of sarcomata may be large or small round cells, or largeor small spindle cells. A sarcoma may develop whereverconnective tissue is abundant—the skin, glandular organs; thevascular sarcoma—-fungus hcematoides—is the most Fig. 88.—Sarcomatous cells, with a few fibres,rrom the dog. CELIULAE TUMOURS. 437 They occur primarily in fasciae, loose subcutaneous tissues, inthe connective tissue of the nerve centres, frequently in theretina, constituting fungus hsematodes; from the periosteum ; andin man from the medullary tissue of bones; and, secondarily,these growths invade the lungs, and afterwards affect themore vascular organs, in which there is a complex capillary-network. When cut into, they are of a uniform soft, brain-like con-sistence, of a reddish white or grey colour, somewhat translucentor opaque, very vascular, the blood-vessels being often dilated,varicose, and liable to rupture, which gives rise to ecchymoses,the formation of blood cysts, and, if the skin be broken, tohaemorrhage. On scraping the cut surface, a thickish juice, richin cells, is obtained, and on this account, as well as their otherclinical characters, they have been confounded
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