410 



C. p. WHITTINGHAM 



obliquus, strain D3, suspended in acid or alkaline media and illumi- 

 nated with "saturating" intensities. 



With the lowest partial pressures of oxygen used the time coui'se 

 separated into two phases: an initial burst followed by a subsequent 

 rise to the steady state. This was first quantitatively investigated by 

 Franck, Pringsheim, and Lad (1) at yet lower partial pressures. 

 In our experiments the separation of the two phases in time was 

 greater the lower the concentration of carbon dioxide and the longer 

 the preceding dark period. The initial burst of oxygen, in contrast 

 with the steady-state production, was not inhibited by 10 ~' M 

 iodoacetamide. In contrast with the Hill reaction, as measured after 

 addition of quinone, the initial burst was inhibited by lO""* M p- 

 chloromercuribenzoate (see Fig. I). Concentrations of fluoride and 

 2,4-dinitrophenol which had no effect on steady-state photosynthesis 



ribose phosphate * — — ■ — 



ATP 



ribose diphosphate 



CO2 



H2O. 



2 PGA 



2ATP, 2H 



2 triose — 

 phosphate 



-^ hexose 



2 phosphoenol pyruvic 

 acid 



2ADP 



2ATP 



;^C fermentation ^ 2 pyruvic acid ^ 2 maHc acid 



product 



2NH3 



4H 



2 alanine 

 Diagram I 



r> 



q 



2 oxalacetic acid 



