Infiltrating and Metastasising Sarcoma of the Rat.

A forthcoming number of theJournal of Experimental Medicinewill contain a detailed description of a mixed-cell sarcoma of the rat which presents many points of similarity with sarcoma of man. The original tumor sprang from the seminal vesicle of a white rat and it has since been transplanted successfully to several hundred rats, both white and mixed gray and white. At first the number of successful transplantations was variable and sank as low as 20 to 30 per cent., but in the last months the successful results have in certain series reached 100 per cent. and averaged about 95 per cent. This increase was achieved by selecting the more rapidly growing tumors, in a young state, for the inoculations. The inoculations have been made under the skin into the muscles, and into the peritoneal cavity. The subcutaneous nodules tend to invade the skin and to cause ulceration; the intramuscular