GROWTH AND METABOLISM 



117 



Somewhat more lipide is accumulated if ammonium rather 

 than nitrate nitrogen is suppUed and high light intensities 

 and low concentrations of free oxygen also favour fat for- 

 mation. Other factors, e.g. phosphate concentration, tem- 

 perature and carbon dioxide supply, are without great 



/•5 3-0 4-5 6-0 7-5 



M/LL/ MOLES OF AMMONIUM CHLORIDE PER LITRE 



90 



FIG. 17. Effect of the initial nitrogen concentration in the culture 

 medium on the lipide content of Chlorella pyrenoidosa (after 

 ref. 264). 



effect. 264 Extremely high proportions of lipide are stored 

 in cells subjected to prolonged incubation under conditions 

 of nitrogen deficiency, as is shown in Table 11, but such 

 cells are not degenerate and will resume growth if trans- 

 ferred to a suitable medium. ^^^ 



