PHOTOSYXTHETIC PHOSPHORYLATION AXD THE ENERGY CONVERSION PROCESS 365 



visualized as occurring between the "terminal" cytochrome and chloro- 

 phvU and is shown in Fig. 4 as being catalyzed by phenazine methosul- 

 phate. (Significant in this connection are the recent findings of James and 

 Leech that, like the bacterial cytochromes in chromatophores, the 



Whole chloroplasts were disrupted by sonic vibration treatment for 10 sec. The 

 grana were isolated by differential centrifugation and filtration through a double 

 layer of Whatman No. 2 filter paper. The isolated grana were fixed for 2 hr. in 

 6"o formaldehyde at pH 6-5. A comparison with similar particles prepared by the 

 freeze-drying technique (Fig. 11) shows that they collapsed in the formaldehyde 

 treatment. The background in the formaldehyde treatment is free from salt 

 (compare with Fig. 11). Magnification : 10 000 x (Muller, Steere, and Arnon [i 18]). 



chloroplast cytochromes, / and b, are "entirely confined to the grana" 

 [120]). At high light intensity the "bypass" pathway catalyzed by phen- 

 azine methosulphate gives high rates of photophosphorylation because it 

 is not limited by the absence of chloroplast constituents that lie outside 

 the grana. The beneficial effect of added chloroplast extract on the FMN 



