338 



C. S, French 



Chlorophyll • 

 I i^ |Phyc«ery*hrin 



450 



500 550 600 650 

 Wavelength, mu 



Fig, 3. The action spectra for O2 production in Porphy - 

 ridium compared with that for production of the substance 

 that increases the rate of O2 uptake measured in two dif- 

 ferent ways. The top curve is the absorption spectrum. 

 French and Fork^^^. 



chlorophyll system found by Duysens and Amesz'^^^ measuring 

 cytochrome changes . 



THE LIFETIMES OF THE PRODUCTS OF THE 

 TWO REACTIONS IN THE DARK 



Myers ^^^^ found that the Emerson enhancement effect could be 

 seen if the two beams were rapidly alternated as well as when they 

 were given together. This implies that at least one of the photo- 

 chemical reactions makes a product that survives the exposure pro- 

 ducing it and that this product makes possible a more efficient 



