DANIEL I. A UN ON 



523 



Fig. 11. Electron micrograph of an osmium-fixed section of a maize chloroplast 

 showing details of structure. The dense areas that resemble stacks of coins are 

 the grana. The layers within each granum are called grana lamellae. The grana 

 lamellae of different grana are interconnected by stroma lamellae. Magnification 

 3.5,000 X. (Courtesy of Dr. A. E. Vatter). 



lation catalyzed by vitamin K or FMN proceeded at a lower rate 

 and was markedly increased by the addition of chloroplast extract; 

 however, even with this increase, it failed to reach the rate of photo- 

 phosphorylation in the phenazine methosulfate system. 



These results support the conclusion that grana are the site of the 

 "primary" photophosphorylation reaction (Equation -/) , the one 

 that is visualized as occurring between chlorophyll and the "terminal" 



