(b) Effects of light/darkness. Coscinodiscus granii cells changed their appearance
according to the light conditions and growth phase: Cgranii cells placed in
continuous darkness for 3 days were slightly paler than those grown under light
conditions, but appeared healthy and resumed growth within 1 day when transferred
back into light. Diatoms in the stationary phase became deeply pigmented
and appeared more compact than those in the logarithmic growth phase. Cell
division was impaired in the stationary phase, and the relationship of single cells
(S) to pairs of not yet divided ('double') cells (D) changed in batch cultures from
2.3 S/D in the logarithmic phase to 0.4 S/D in the stationary phase, while the
chlorophyll content per cell increased from -300-320 pg cell"1 to 950 pg cell"1 (not
shown; 'double' cells were counted as two cells).