375 



C.P. .-Jhittingham and P.M. Bishop 



all the systems studied. In the case of chloroplasts reducing 

 ferricyanide and TPIP, where oxygen vjas produced from the single 

 short flash itself, the yield from the pair of flashes was con- 

 siderably greater than the sum of the yields from the two flashes 

 when these were given separated by a very long dark interval . 



The optimum dark period betvjeen the two flashes at ii;hich maxi- 

 mum yield was obtained from the second flash, varied according to 

 the oxidant used, as can be seen from figure 1. 



'i Iiicifasi 



20 

 Tunc in sit 



Figure 1 Relationship between the combined yield of oxygen for a 

 short and long flash as a function of the dark time separat- 

 ing the two flashes. The yield is expressed as percentage 

 increase over the yield of the long flash given alone. 



O ferricyanide with phosphorylating reagents 

 # ferricyanide with ammonium chloride 

 O ferricyanide with catalytic amounts of TPIP 

 X TPIP 



The data obtained vi7ith chloroplasts reducing ferricyanide 



