Starting from ascites fluid from rats bearing intraperitoneal solid tumour, the ascites type of 256 Walker carcinosarcoma was obtained and steadily maintained. A varying latency period in the ascites development and a highly variable taking percentage has been demonstrated in the tested strain. On the other hand, the number of neoplastic cells contained in 1 ml ascites fluid was found to be constant and high (4 to 6 millions/ml.).
