ACCUMULATION OF (203) HG BY THE MARINE DIATOM CHAETOCEROS COSTATUM.

Dividing and nondividing cell populations of Chaetoceros costatum Pavillard were placed in light; nondividing populations were also placed in the dark, and one population was killed by formalin. No difference in(203) Hg uptake was seen in nondividing cells in the light and dark, while cells accumulated about 2 times as much(203) Hg as living cells, presumably by surface adsorption. Dividing cells in light accumulated(203) Hg longer than did nondividing cells, indicating the possibility of some active uptake of Hg.