The inhibition by guinea pig serum of the growth of the Murphy-Sturm lymphosarcoma.

Kidd (7) showed that there is a spectrum of in hibitory activity of guinea pig serum against lymphomas transplanted in rats and mice. Experiments previously reported from our labo ratory (Jameson et al. [6]) demonstrated that guinea pig serum was effective in delaying the on set and slowing the growth of the ACMCA2 fibro sarcoma when carried in the AXC 9935 strain of the Irish gray rat. This tumor had no spontaneous regressions in the host. This work was extended to study the effect of guinea pig serum against the Murphy-Sturm lymphosarcoma, which was reported to have 20 per cent spontaneous regressions (Dunham and Stewart [3]).