36 



PROBLEMS IN PHOTOSYNTHESIS 



Fig. 13. Cells of Chlorella pyreiioidosa. 

 Diameter: 3-5 n. 





% 



« 





-\* 



* ♦ 



» 

 f 







#|J^ 







C9, ^ 











3 



Fig. 14. Cultivation equipment for Chlorella in Prof. Warburg's institute. 



The distance between the lamp and the culture flasks is 25 cm. The 

 culture solution* contains the essential trace elements (see §32) and is aerated 



* The culture solution K contains, per liter of quartz-distilled water, 5 g MgS04.7H20 + 2.5 g 

 KH2PO4 + 2 g NaCl + 2 g KNO.3 + 0.5 g Ca(N03)2.4H20. The pH is approximately 4.2 but 

 rises during the culture period (30, 31 ). Another culture solution is the sah solution S in which the 

 nitrate is replaced by 0.2 g NH4CI. 



