FURTHER OBSERVATIONS ON GROWTH OF SINGLE CELLS OF COCCOID BLUE-GREEN ALGAE.

Initiation of growth (lag) and subsequent growth to visible colonies was examined for single cells of several coccoid blue-nreen algae under controlled incuba-tion conditions. At 30 or 39 C, with tungsten or fluorescent illumination, organisms such as Agmenel-lum quadruplicatum, strains PR-6 and strain BG-J, showed no evidence of lag associated with initiation of growth. The final colony count was within 20% of the expected number derived from cell counts and serial dilutions. For Anacystis nidulnns, Tx 20, a new medium C, 10 with EDTA as chelator was developed. In this medium groiuth of single cells at 39 C was excellent with quantitative recovery and no evidence of lag. At 30 C, however, Tx 20 showed anomalous behavior, lag and nonquantitative cell recovery. This behavior at 30 C is not yet understood.