Lymphoma cells (Eb and ESb, the metastasizing variant) were injected via a mesenteric vein. 85% to 95% of these cells were trapped in the liver. Most of the Eb cells (81%) were destroyed within 18 hours, ESb cells prove to be more resistant: only 28% of these cells were destroyed within this time. 51-Chromium release assay (4 hours) revealed a similar sensitivity of these two tumor cell strains.