Chlamydomonas: Colored Excretion Products.

Particle-free media in which pure cultures of the green alga Chlamydomonas moewusii have been growing are yellow. In its solubility, chromatographic behavior, fluorescence, response to changes of pH, and optical absorption, the coloring matter closely resembles mixtures of substances previously held responsible for the yellow color of some pond waters. Our findings suggest that the yellow materials of natural waters may originate from algal metabolism.