PRECISE MEASUREMENT OF THE CHANGE OF STATISTICAL DISTRIBUTION OF CELL SIZE OCCURRING DURING THE SYNCHRONOUS CULTURE OF CHLORELLA

Change of statistical distribution of cell size occurring inthe synchronous culture of Chlorella ellipsoidea was followedby using a COULTER counter. The culture was started using apopulation of D-cells which showed a sharp distribution of cellsize. During the growth phase, there occurred characteristicchanges in the height and shape of the distribution curve; namely,the height first decreased with broadening of the distributionand then increased to the level even higher than the originalpeak. The broadening of the curves, which indicates the loweringof degree of homogeneity of population, occurred during theperiod of most active growth, and the homogeneity was restoredat later stages of ripening where the growth became sluggish.When the ripened cells (L₃) were transferred to the darknesstheir volume decreased to some extent before the occurrenceof cellular division. It was assumed that the shrinkage of cellsobserved may be partly due to exudation of water from the cellsand partly to the consumption of fuel material caused by enhancedrespiration, both having been shown to occur at the stage ofcell maturation. (Received June 12, 1964; )