ACTION SPECTRUM OF RED AND BLUE ALGAE 



1179 



1943, by a systematic investigation of the relation between wave length 

 and quantum yield in this Cyanophycea. 



Chroococcus cells are somewhat smaller than Chlorella (2.5 ju in diame- 

 ter) and are surrounded by a gelatinous sheath. They scatter less light 



0.10 

 008 



Q 



_l 

 ill 



> 006 



3 



< 



O 



004 



0.02 



, .X' 





J 



Observed 

 Colculoted 





*-♦-..,. 



400 440 480 



520 560 600 640 

 WAVE LENGTH, m^ 



_L 



680 720 



Fig. 30.10A. Quantum yield of Chroococcus photosynthesis (after Emerson and Lewis 

 1942). SoHd line is drawn through experimental points, values obtained in different 

 runs being distinguished by different characters. Broken line shows expected dependence 

 of quantum yield on wave length, on assumption that -yield for light absorbed by chloro- 

 phyll and phycocyanine is 0.08 at all wave lengths, and light absorbed by carotenoids is 

 not available for photosynthesis. 



100 



Direct 



From Photosynthesis 



10 mm cells/ml 



08 mm. ceils/ml. 

 J L 



400 



700 



500 600 



WAVE LENGTH, mp. 



Fig. 30.10B. Comparison of action spectrum (broken curve) and ab- 

 sorption spectrum of Chroococcus (after Emerson and Lewis 1942). 



than Chlorella cells (probably because of the absence of chloroplasts ; cf. 

 chapter 15, page 355). This makes the determination of the absorption 

 curve easier, and leads to better agreement between the absorption curve 

 of the intact cells and the curve constructed by the combination of the 

 (appropriately shifted) absorption curves of the extracted pigments (illus- 



