Caffeine bleaching of Stentor coeruleus.

Abstract

AbstractAfter a few days in caffeine solution the dark blue‐green ciliate Stentor coeruleus loses all visible pigmentation. The cells remain viable and transparent if the solution is then diluted. In time, however, a light pink color is regenerated in maintenance concentration of the drug. In caffeine‐free medium the major dark green pigment is regenerated. Decolorized, pink, and normal stentors can thus be compared, alive, in searching for the functions of these pigments. Unexpectedly, the pigments are not necessary for the lightavoidance response.