Abstract
In the experiments here described transplanted lymphomas of two kinds regularly regressed following repeated injections of normal guinea pig serum intraperitoneally into mice carrying them, the animals meanwhile remaining lively and devoid of signs of illness or wasting. The lymphomas of untreated control mice, by contrast, usually grew progressively and killed their hosts within 20 to 30 days, and the same was true of the growth of other mice given repeated injections of horse serum or rabbit serum.